Soft Tissue [Discontinued] by ProSol

POSSIBLY EFFECTIVE

• Osteoarthritis. Oral Boswellia serrata extracts, taken alone or in combination with other ingredients, appear to reduce pain and stiffness and improve function in knee osteoarthritis. However, most clinical studies have been small and of relatively short duration. Details: A meta-analysis of 11 moderate- to lower-quality clinical studies in adults with knee osteoarthritis shows that taking an herbal formulation containing Boswellia (15-600 mg daily) or a Boswellia extract exclusively (100-1000 mg daily) for 1 to 8 months does not improve subjective scores evaluating pain, stiffness, and physical function when compared with a control such as glucosamine sulfate or valdecoxib. However, sub-group analyses show improvement in pain, stiffness, and functionality with an herbal formulation containing Boswellia compared with placebo, although the clinical significance is unclear (115731). The validity of these results are limited due to the lack of data on the herbal formulations. A similar meta-analysis including 7 of the same clinical studies plus 2 other, higher quality clinical studies shows that taking Boswellia serrata extract reduces pain and stiffness and improves function when compared with placebo (114684). Furthermore, individual trials, some included in the meta-analyses above, have shown similar results with specific Boswellia serrata supplements or extracts including 5-Loxin, Aflapin, Boswellin, Wokvel, and Boswellin Super (109564,100699,12432,103784,115735). Several studies also show that taking specific combination products containing Boswellia serrata and other ingredients can improve pain and functionality in patients with osteoarthritis. These products have combined Boswellia serrata 100 mg with ashwagandha 450 mg, turmeric 50 mg, and zinc complex 50 mg (Articulin-F) three times daily for 3 months (19276); Boswellia serrata 100 mg with ginger 33.33 mg, Tinospora cordifolia 73.33 mg, and Indian gooseberry 166.66 mg three times daily for 6 months (89557); a specific Boswellia serrata extract (BosPure, Arjuna Natural Extracts Ltd) 300 mg with turmeric extract (BCM 95, Arjuna Natural Extracts Ltd) 700 mg daily for 12 weeks (89719); boswellic acid 7.2 mg (from Boswellia serrata) with methylsulfonylmethane 5 grams and vitamin C daily for 2 months (96446); and a specific combination product (Tregocel, Max Biocare) providing Boswellia serrata extract 1 gram, curcumin 100 mg, devil's claw tuber 1 gram, celery seed 1 gram, and ginger rhizome 330 mg daily for 36 weeks (106078). However, research in patients with osteoarthritis of the hand suggests that taking a combination of Boswellia serrata extract 250 mg, pine bark extract 100 mg, methylsulfonylmethane 1500 mg, and curcumin 168 mg daily for 12 weeks does not improve pain or functionality (109563).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there is interest in using oral Boswellia serrata for hay fever, there is insufficient reliable information about the clinical effects of Boswellia serrata for this condition.
• Alzheimer disease. It is unclear if oral Boswellia serrata improves cognitive function in patients with Alzheimer disease. Details: A small clinical study in adults with mild to moderate Alzheimer disease shows that taking a specific Boswellia serrata extract (K-Vie, Kondor Pharma) 1200 mg daily for 6 months improves neuropsychiatric symptoms, dementia severity, and some but not all measures of cognitive function when compared with placebo (112807).
• Aromatase inhibitor-induced arthralgia. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with estrogen receptor positive (ER+) breast cancer and aromatase inhibitor-induced arthralgia shows that taking a specific combination product (Opera, Gamfarma Srl) containing Boswellia serrata 40 mg, alpha-lipoic acid 240 mg, methylsulfonylmethane 200 mg, and bromelain 20 mg once daily for 6 months reduces arthralgia intensity when compared to baseline, with around 22% of patients having complete symptom resolution at the end of the study (109570). The validity of these findings is limited by a lack of control group.
• Asthma. It is unclear if oral Boswellia serrata can improve symptoms of asthma. Details: One small preliminary clinical study in patients with asthma suggests that taking a specific Boswellia serrata gum resin (S-compound, Rahul Pharma) 300 mg three times daily for 6 weeks may improve symptoms of asthma, such as forced expiratory volume (FEV), the number of asthma attacks, and dyspnea and rhonchi, in 70% of patients, compared to only 27% of patients in a control group (1708).
• Brain tumor. It is unclear if oral Boswellia serrata improves outcomes in patients with brain tumors. Details: One small clinical study in adults with brain tumors undergoing radiation therapy shows that taking an H15 Boswellia serrata extract 4200 mg in three divided doses daily throughout radiotherapy reduces cerebral edema and tumor volume, but not dexamethasone dosage, when compared with placebo (21149).
• Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS). Rectal Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Two small, open-label clinical studies in males with prostatitis-like symptoms or CP/CPPS types IIIa or IIIb shows that rectal administration of a specific suppository containing Boswellia serrata resin extract and propolis polyphenols (MICTALASE) once daily for 20 days or once daily for 15 days per month for 3 months improves pain, urinary symptoms, quality of life, and total symptom scores, as measured by the Chronic Prostatitis Symptom Index (CPSI), when compared to baseline. However, there were no improvements in scores on the International Index of Erectile Dysfunction (IIED), and studies showed mixed findings regarding improvements on the International Prostate Symptoms Score (IPSS) (102091,109566). The validity of these results is limited by the lack of a comparator group.
• Cluster headache. Although there is interest in using oral Boswellia serrata for cluster headache, there is insufficient reliable information about the clinical effects of Boswellia serrata for this condition.
• Coronavirus disease 2019 (COVID-19). Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in adults hospitalized with moderate COVID-19 infection in Egypt shows that taking Boswellia serrata extract 300 mg and licorice extract 300 mg twice daily for 14 days, along with conventional therapy, reduces the risk of death, shortens the time to hospital discharge by around 5.5 days, and reduces the rate of mechanical ventilation when compared with placebo. For every five patients treated with this combination product, one additional patient survived. The standard treatments administered in this study included azithromycin, vitamin C, and zinc (108579). Another large clinical study in adults hospitalized with moderate COVID-19 infection in India shows that taking a specific product containing Boswellia serrata, ashwagandha, ginger, and turmeric (Artovid-20, Bioved Pharmaceuticals, Inc) 1,776 mg twice daily after meals for 14 days, starting within 48-96 hours of symptom onset along with conventional therapy, decreases the duration of illness by about 1 day and reduces patient-assessed severity scores of various symptoms (e.g. nasal congestion, sore throat, cough, taste and smell disorders) when compared with placebo. Almost all patients in this study also received steroids, and over 50% received remdesivir. Study results were similar in the subgroup of patients who received remdesivir (109899). However, the validity of this study is limited by use of data only from patients who fully adhered to the study protocol per protocol analysis and exclusion of patients with risks for progression to severe COVID-19, including uncontrolled hypertension, asthma, chronic obstructive pulmonary disease, diabetes, obesity, or immunocompromise.
• Crohn disease. It is unclear if oral Boswellia serrata reduces relapse rates in patients with Crohn disease. Details: One small clinical study in patients with Crohn disease who are in remission shows that taking Boswellia serrata (Boswelan, Pharmasan) 800 mg orally three times daily for one year does not decrease relapse rates or improve quality of life when compared with placebo (17241).
• Diabetes. It is unclear if oral Boswellia serrata improves glycemic control in patients with diabetes. Details: A meta-analysis of five moderate- to low-quality studies in adults with type 2 diabetes shows that taking Boswellia gum resin 500 -900 mg daily or Boswellia powder 1200 mg daily for 6-12 weeks reduces glycated hemoglobin (HbA1C) but not fasting blood glucose when compared with placebo or no treatment. Additionally, triglycerides were reduced, but other lipid parameters were not improved (115732). A smaller meta-analysis pooling the results of two trials included in the previously described meta-analysis shows that Boswellia serrata reduces HbA1c by about 0.5% and fasting blood glucose by about 24 mg/dL, with no improvement in lipid levels, when compared with placebo (111503). Overall, the validity of these findings is limited by heterogeneous methods between clinical trials, such as treatment dose and duration, and the lack of data regarding other medications used for diabetes.
• Diarrhea. It is unclear if oral Boswellia serrata is beneficial in patients with acute diarrhea. Details: A small clinical study in adults with acute diarrhea shows that taking a specific lecithin-based delivery form of Boswellia serrata extract (Casperome, Indena S.p.A.) 250 mg twice daily for 5 days decreases the time to diarrhea resolution by nearly 1.4 days, reduces stool frequency, and improves symptoms of abdominal pain and nausea when compared with placebo (109568).
• Dysmenorrhea. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in adults with moderately painful dysmenorrhea shows that taking a single dose of a combination product containing Boswellia serrata, turmeric, and sesame (Rhuleave-K, Arjuna Natural Private Ltd.) 1000 mg at the start of menstruation relieves menstrual cramp pain and reduces pain intensity for up to 6 hours when compared with placebo (112806). It is unclear if these effects are due to Boswellia serrata, other ingredients, or the combination.
• Exercise-induced muscle soreness. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in healthy active adults with moderate to severe exercise-induced muscle pain shows that taking a single, 1000-mg dose of Boswellia serrata and turmeric extracts in black sesame oil (Rhuleave-K; Arjuna Natural Private Ltd.) improves pain relief when compared with placebo, with maximal benefits within about 3 hours. The number of people needed to treat to obtain pain relief of at least 50% over a 6-hour period was 1.1 (109277).
• Irritable bowel syndrome (IBS). Small clinical studies suggest that an oral Boswellia serrata extract may improve symptoms of IBS. Details: A small clinical study in patients with mild IBS shows that taking a specific lecithin-based delivery form of Boswellia serrata extract (Casperome, Indena S.p.A.) 250 mg daily for 6 months reduces abdominal pain, cramps, and gas when compared with standard management with hyoscine butylbromide or papaverine hydrochloride plus belladonna extract 10 mg. Patients receiving Casperome required fewer rescue medications and had a 46% lower risk of needing additional medical care, including hospitalization (100713). In a short-term clinical trial of the same Boswellia serrata extract 250 mg daily for 4 weeks, the risk for requiring additional medical care was reduced by 67% when compared with the same standard treatment options above. While IBS symptoms improved over baseline, significant differences between Casperome and standard treatment options were lacking (102089). These studies were funded by the supplement manufacturer, which may limit the reliability of these findings.
• Knee pain. It is unclear if oral Boswellia serrata is beneficial for knee pain. Details: A small clinical study in otherwise healthy adults with knee pain shows that taking Boswellia serrata extract 12.5% tablets twice daily for 8 weeks improves physical function and pain but not stiffness, functional mobility, muscle function, or level of physical activity when compared to baseline (112808).
• Menorrhagia. It is unclear if oral Boswellia serrata is beneficial for menorrhagia. Details: A small clinical study in otherwise healthy adults with menorrhagia shows that taking Boswellia serrata oleoresin powder 300 mg three times daily for 7 days, repeated over 2 menstrual cycles, improves quality of life and modestly reduces the average duration of menstrual bleeding after the second cycle when compared with placebo. All patients were permitted to use ibuprofen 200 mg as needed (105401).
• Microscopic colitis. There is limited evidence on the oral use of Boswellia serrata in patients with collagenous colitis. Details: One small clinical trial shows that taking Boswellia serrata extract 400 mg three times daily for 6 weeks increases the clinical remission rate by 64% when compared with placebo in patients diagnosed with a type of microscopic colitis called collagenous colitis. Clinical remission was defined as having an average of three or fewer soft or solid stools daily during the last week of the study (21152).
• Pain (acute). Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with acute musculoskeletal pain shows that taking a specific combination product containing Boswellia serrata and turmeric extracts in black sesame oil (Rhuleave-K; Arjuna Natural Private Ltd.) 1000 mg daily for 7 days is as effective as acetaminophen 1000 mg daily for pain relief, onset of pain relief, and onset of maximal pain relief (109287). This study is limited by its lack of blinding and placebo control. Additionally, the dose of acetaminophen used in this study is below the standard recommended daily dose.
• Pharyngitis. Although there is interest in using oral Boswellia serrata for pharyngitis, there is insufficient reliable information about the clinical effects of Boswellia serrata for this condition.
• Postoperative pain. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study in adults undergoing hernioplasty shows that taking a specific combination product (Siben®, Agaton Srl) containing 200 mg each of Boswellia serrata and bromelain twice daily for 11 days after surgery reduces pain on postoperative days 7 and 21, but not day 1, when compared with placebo. While the difference in pain scores on day 21 was statistically significant, pain was rated as mild in both groups; any difference may not be considered clinically significant (114687).
• Rheumatoid arthritis (RA). Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical trial in patients with RA shows that taking two capsules of a specific product containing Boswellia serrata 100 mg, ashwagandha 450 mg, turmeric 50 mg, and zinc complex 50 mg (Articulin-F) three times daily for 3 months improves pain, morning stiffness, grip strength, and disability scores when compared with placebo (21154). However, another clinical trial in patients with RA shows that taking two tablets of a standardized extract formulation (RA-1) containing Boswellia serrata, ashwagandha, ginger, and turmeric three times daily for 16 weeks does not improve most symptoms when compared with placebo (21155).It is unclear if these findings are due to Boswellia serrata, other ingredients, or the combination.
• Rhinosinusitis. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients over 12 years of age with chronic sinusitis shows that taking a combination product containing Boswellia serrata, black currant, bromelain, and vitamin D (Flogostop Forte, Humana Italia) with inhaled corticosteroids daily for 30 days reduces rhinorrhea, hyperemia of mucosa, and local inflammation when compared with inhaled corticosteroids alone (111501). It is unclear if these findings are due to Boswellia serrata, other ingredients, or the combination.
• Stroke. It is unclear if oral boswellic acids improve neurological function after stroke. Details: One small clinical study in adults with recent ischemic stroke who are taking aspirin and clopidogrel shows that taking boswellic acids 800 mg three times daily for 30 days improves neurological function, as measured using the National Institutes of Health Stroke Scale, when compared with placebo (102092).
• Traumatic brain injury (TBI). It is unclear if oral Boswellia serrata is effective for reducing disability, or improving cognitive function or memory in adults recovering from TBIs. Details: A small clinical crossover study in adults admitted to the hospital for diffuse axonal injury shows that taking powdered Boswellia serrata oleogum resin 360 mg three times daily for 6 weeks does not improve disability when compared with placebo (91379). However, another small clinical study in patients suffering from a TBI 3 months to 3 years earlier shows that taking a specific Boswellia serrata extract (K-Vie, Kondor Pharma) 400 mg three times daily for 3 months improves performance on cognitive function tests, including those assessing processing speed, memory, and overall cognitive function, when compared with placebo (109567). A moderate-size clinical study in adults with memory dysfunction due to a recent mild traumatic brain injury in Iran shows that taking a specific product containing Boswellia serrata 360 mg and ginger 36 mg (Memoral, Goldarou) three times daily for 1 month modestly improves practitioner-assessed memory function scores when compared with placebo (110132). However, it is unclear if this effect is due to Boswellia serrata, ginger, or the combination.
• Ulcerative colitis. Small clinical studies suggest that oral Boswellia serrata extracts may improve symptoms of ulcerative colitis. Details: Two very small clinical trials in patients with active ulcerative colitis suggest that taking Boswellia serrata gum resin 300-350 mg three times daily for 6 weeks improves symptoms and disease markers comparably to taking sulfasalazine 1 gram three times daily (1709,12438). These findings are limited because the sample size may have been inadequate to assess differences between groups. In patients with ulcerative colitis in remission, one observational study has found that taking a specific lecithin-based delivery form of Boswellia serrata extract (Casperome, Indena S.p.A.) 250 mg daily for 4 weeks is associated with a reduction in abdominal pain, cramps, and malaise, a decrease in the need for additional medications, and a 58% lower risk for requiring additional medical care when compared with no treatment. Additionally, weekly episodes of bloody diarrhea, bowel movements, and watery stools were reduced when compared with baseline (102090).
• Urinary incontinence. Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in postmenopausal adults with urinary incontinence shows that taking a 3 tablets of a multi-ingredient herbal product containing Boswellia serrata 100 mg and five other herbs twice daily for 4 weeks reduces urinary incontinence frequency and leakage amount when compared with placebo, with improvements similar to those reported with solifenacin as standard therapy (111502). It is unclear if these effects are due to Boswellia serrata, other ingredients, or the combination.
• Urinary tract infections (UTIs). Oral Boswellia serrata has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small observational study in patients with an uncomplicated UTI has found that taking two tablets of a specific combination product (Acidif plus) containing Boswellia serrata gummy dry extract 100 mg, L-methionine 400 mg, and hibiscus 100 mg daily for 7 days is associated with reduced UTI symptoms and reduced bacteriuria when compared with taking an unreported dose of fosfomycin for 2 days (103783). The validity of this study is limited by its observational nature and a lack of information on the severity of UTI at baseline. Also, it is unclear if these effects are due to Boswellia serrata, other ingredients, or the combination. More evidence is needed to rate Boswellia serrata for these uses.

(Read more about BOSWELLIA SERRATA)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there has been interest in using oral bromelain for allergic rhinitis, there is insufficient reliable information about the clinical effects of bromelain for this condition.
• Aromatase inhibitor-induced arthralgia. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with aromatase inhibitor-induced arthralgia shows that taking a specific combination product (Opera, Gam Farma), providing bromelain 20 mg, alpha-lipoic acid 240 mg, Boswellia serrata 40 mg, and methylsulfonylmethane 200 mg, daily for 6 months reduces arthralgia symptoms when compared to baseline (109570). The validity of these findings is limited by a lack of placebo control group. Further, it is unclear if these findings are due to bromelain, other ingredients, or the combination.
• Burns. Preliminary clinical research shows that topical bromelain is beneficial for burn debridement. However, it is unclear if topical bromelain is beneficial for scar prevention. Details: Preliminary clinical research and chart reviews show that gels formulated with proteolytic enzymes derived from bromelain (Debridase or NexoBrid, MediWound Ltd.) applied under an occlusive dressing for 4 hours help debride burns, including chemical and electrical burns, in children and adults (18275,91113,103297,108149). Further, a meta-analysis of up to 5 lower- to moderate-quality clinical and observational studies in children and adults with deep burns shows that enzymatic debridement with a specific bromelain based proteolytic enzyme gel applied once or twice for a 4 hour period reduces eschar time by approximately 7 days and reduces the relative risk of surgical excision, and autografts by 83%, and 60%, respectively, when compared with standard of care (e.g., surgical and non-surgical procedures) (115870). The validity of these results is limited by significant heterogeneity across clinical studies, including differences in the location of burns and extent of total body surface area affected.
• Cancer. Although there has been interest in using oral bromelain for cancer, there is insufficient reliable information about the clinical effects of bromelain for this condition.
• Chemotherapy-induced peripheral neuropathy. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in adults with chemotherapy-induced peripheral neuropathy shows that taking a specific product (Opera, Gamfarma s.r.l.) containing bromelain 20 mg, alpha-lipoic acid 240 mg, methylsulfonylmethane (MSM) 200 mg, and boswellia 40 mg daily for 12 weeks reduces overall pain when compared with baseline (96449). The validity of these findings is limited by the lack of a control group. Additionally, it is not clear if benefit is due to alpha-lipoic acid, the other ingredients, or the combination.
• Chronic venous insufficiency. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: An observational study in adults with chronic venous insufficiency using compression stockings shows that taking a specific supplement containing bromelain dry extract 50-200 mg, Baikal skullcap, and horse chestnut (Lenidase, Enfarma), dose adjusted based on severity, daily for up to 90 days, improves severity of lower extremity symptoms (e.g., inflammation, pain, varicose veins, vessel induration) when compared with the use of compression stockings alone (115869). It is unclear if these benefits are due to bromelain, the other ingredients, or the combination.
• Diabetes. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small observational study in patients with a family history of type 1 diabetes found that taking a specific product (Mucos Pharma) containing bromelain 90 mg. rutin 100 mg, and trypsin 48 mg daily for 24 months is not associated with reduced incidence of type 1 diabetes at 8 years (99472).
• Diabetic foot ulcers. Although there has been interest in using topical bromelain for diabetic foot ulcers, there is insufficient reliable information about the clinical effects of bromelain for this condition.
• Exercise-induced muscle soreness. It is unclear if oral bromelain is beneficial for preventing exercise-induced muscle soreness. Details: One small clinical study shows that taking bromelain 300 mg three times daily, immediately following an intense exercise regimen, does not reduce delayed onset muscle soreness and has no effect on pain, flexibility, or skeletal weakness when compared with either ibuprofen 400 mg three times daily or placebo (10622). However, a small clinical study shows that taking a combination protease tablet containing bromelain 50 mg, trypsin 75 mg, papain 50 mg, amylase 10 mg, lipase 10 mg, lysosome 10 mg, and chymotrypsin 2 mg, four times in one day before downhill running, can improve recovery of contractile muscle function and decrease muscle soreness when compared with placebo (67838). It is unclear if these effects are due to bromelain, other ingredients, or the combination.
• Exercise-induced respiratory infections. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in non-elite male runners shows that taking a combination product (Wobenzym Plus, Mucos Pharma) providing bromelain 540-1080 mg, rutin 600-1200 mg, and trypsin 288-576 mg daily for 3 weeks, starting one week before a marathon, does not reduce the risk of a post-race respiratory tract infection when compared with placebo (96766).
• Kidney stones (nephrolithiasis). It is unclear if oral bromelain is beneficial for kidney stone expulsion. Details: Observational research in patients with 4-10 mm kidney stones found that adding bromelain to tamsulosin is associated with a 12% increased rate of spontaneous stone expulsion when compared to tamsulosin alone (100752).
• Knee pain. It is unclear if oral bromelain is beneficial for knee pain. Details: Preliminary clinical research shows that taking bromelain (Bromelin, Lichtwer Pharma Ltd.) orally for 30 days can reduce mild, acute (duration of less than 3 months) knee pain in otherwise healthy patients when compared to baseline. A daily dose of 400 mg seems to be more effective than 200 mg daily for relieving pain, stiffness, and physical function of the knee, with reductions in symptom scores of 59% and 41%, respectively (11457).
• Lymphedema. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some clinical research in patients who have undergone a mastectomy shows that taking a specific combination product containing bromelain, rutin, pancreatin, papain, trypsin, and chymotrypsin (Wobenzym N, Mucos Pharma) daily for 7 weeks reduces arm swelling associated with lymphedema when compared with diuretics (24560). Other preliminary clinical research in patients with primary or secondary lymphedema of the upper or lower limbs shows that taking a different combination product containing bromelain 100 mg, rutin 300 mg, and sweet clover 100 mg daily for 6 months decreases pitting, limb volume, pain, and quality of life when compared to baseline (103298). The validity of these results is limited by the lack of a control group. Additionally, it is unclear if these findings are due to bromelain, other ingredients, or the combination.
• Multiple sclerosis (MS). Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A preliminary clinical study in patients with relapsing-remitting MS shows that taking an enzyme combination containing bromelain 90 mg, rutin 100 mg, and trypsin 48 mg per tablet for at least 3 months does not affect the progression of disability, relapse rate, or central nervous system lesions when compared with placebo (99468). The validity of these results is limited by the short duration of treatment.
• Ocular floaters. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in patients with spontaneous symptomatic vitreous opacities (ocular floaters) shows that taking oral mixed fruit enzyme capsules containing bromelain 190 mg, papain, and ficin once, twice, or three times daily for 3 months eliminates floaters in 55%, 63%, and 70% of patients, respectively, when compared with an elimination rate of 5% with vitamin C as a control. Additionally, patients with vitreous hemorrhage-induced symptomatic vitreous opacities taking the mixed fruit enzyme capsules 3 times daily for 3 months reduced intraocular blood by 56% and improved visual acuity, but these effects were not found for lower doses and shorter durations when compared with a control (111650). It is unclear if these effects are due to bromelain, other ingredients, or the combination.
• Osteoarthritis. It is unclear if oral bromelain is beneficial for osteoarthritis. Details: A small clinical trial shows that taking bromelain 800 mg daily for 12 weeks as an adjunctive treatment for moderate to severe knee osteoarthritis is no more effective than placebo for improving symptom scores (18274). Other preliminary clinical research shows that taking bromelain 500 mg daily for 4 weeks for mild to moderate knee osteoarthritis is less effective than diclofenac 100 mg daily for improving quality of life, joint pain, and joint function (96216). However, preliminary clinical research shows that oral combination products containing bromelain can reduce pain and improve function in knee osteoarthritis (6252,91104,91106,99467,99477,103299). Bromelain 180 mg has been used in combination with trypsin 144 mg and rutin 200 mg (Phlogenzym, Mucos Pharma GMBH; Wobenzym, Mucos Pharma GmbH) three times daily for 3-12 weeks, with effects comparable to diclofenac, usually taken as 50 mg three times daily for one week, then twice daily thereafter. This product also reduces the need for rescue analgesics by 95% when compared with placebo (6252,91104,99467,99477). Other studies have used a specific combination supplement (AINAT, Laboratoire de Rhumatologie Appliquée) containing Devil's claw 600 mg, turmeric 400 mg, and bromelain 300 mg, taken 2-3 times daily for 2-8 weeks (91106) or a combination of bromelain 250 mg and papain 250 mg (Nature's Life Bromelain & Papain, NutraMarks, Inc.) twice daily, plus aceclofenac 100 mg twice daily for 6 weeks (103299).
• Pain (acute). It is unclear if oral bromelain is beneficial for acute pain. Details: A meta-analysis of 9 small clinical studies in patients experiencing acute pain due to various etiologies shows that taking bromelain slightly improves subjective pain scores and allows patients to open their mouth wider after oral operations when compared with a control (113513).
• Parturition. Although there has been interest in using oral bromelain for shortening the duration of labor, there is insufficient reliable information about the clinical effects of bromelain for this purpose.
• Periodontitis. It is unclear if oral bromelain is beneficial for periodontitis. Details: A very small clinical study in adults with periodontitis shows that taking bromelain 500 mg (Anaheal) twice daily for one week after undergoing pocket elimination surgery reduces bleeding on probing but does not improve gingival index, plaque index, or probing pocket depth when compared with placebo when assessed five weeks after surgery (111691). The validity of these effects is limited by a very small sample size and inadequate statistical power.
• Pityriasis lichenoides chronica (PLC). It is unclear if oral bromelain is beneficial for PLC. Details: A case series suggests that taking bromelain 40 mg orally three times daily for one month, then twice daily for a second month, then once daily for a third month, helps treat episodes of PLC when compared to baseline (18280).
• Postoperative pain. While evidence is mixed, some small clinical studies suggest that oral bromelain reduces postoperative pain after some oral surgeries. Details: Meta-analyses and clinical research in a small number of patients undergoing wisdom tooth extraction shows that bromelain modestly reduces pain for up to 8 days when compared with control (91109,91110,100750,100751). In contrast, several other small clinical studies show that taking bromelain does not reduce pain after wisdom tooth extraction when compared with placebo (91107,96214,96215). These studies might not have been sufficiently powered to detect a smaller effect. Meta-analyses also suggest that bromelain does not appear to have a significant effect on postoperative swelling or trismus (100750,100751). Additionally, multiple clinical studies in patients undergoing oral procedures, including crown lengthening or root canal surgery, shows that bromelain 160-1500 mg, taken in 2-4 divided doses daily for up to 6 days, reduces dental pain, swelling, and trismus similarly to taking non-steroidal anti-inflammatories (e.g., ketoprofen, diclofenac sodium, aceclofenac, and ibuprofen) (91109,91110,110546,113898,115871,110546). Bromelain, in combination with other ingredients, has also been evaluated for reducing pain after surgery. Several clinical trials in adults undergoing a variety of surgery types, including facial trauma, hernioplasty, oral surgery, and shoulder surgery, show that taking specific combination products (Siben, Brovas, Tenosan) containing bromelain and other ingredients (e.g., freeze-dried pineapple, methylsulfonylmethane, Boswellia serrata) daily for 1 week to 3 months reduces postoperative pain (115868,19322,114687,115304). However, clinical significance is unclear. Additionally, it is unclear if the effect is due to bromelain, other ingredients, or the combination.
• Postoperative swelling. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical study in patients undergoing surgery of the jaw shows that taking an enzyme combination of bromelain 180 mg, rutin 200 mg, and trypsin 96 mg twice daily for 5 days in addition to standard treatment reduces soft-tissue thickness (indicating the amount of swelling) at most of the nine assessed facial points when compared to control (99476).
• Rhinosinusitis. It is unclear if oral bromelain is beneficial for rhinosinusitis. Details: Several small clinical trials show that short-term and long-term use of bromelain reduces symptoms of acute and chronic sinusitis, especially nasal mucosal inflammation and edema (18276,18277,18278,18279,91105). The trials used bromelain 40 mg orally (usually the product Ananase) four times daily for six days as an adjunct to antibiotics (18276,18278,18279) or 6 bromelain tablets each containing enzymes of 500 International Pharmaceutical Federation (FIP) units for 12 weeks (91105). Bromelain is usually taken in combination with decongestants, antihistamines, and/or antibiotics. However, the studies have a number of methodological problems, and results are inconsistent. Bromelain has also been evaluated as part of a combination product. A small study in patients over 12 years old with chronic sinusitis shows that taking a combination product containing bromelain 200 mg, Boswellia serrata, black currant, and vitamin D (Flogostop Forte, Humana Italia S.p.A) 1-2 times daily for 15-30 days as an adjunctive therapy to inhaled corticosteroids modulates hyperemia of the mucosa, rhinorrhea, and local inflammation when compared with inhaled corticosteroids alone and baseline (111501). It is unclear if these findings are due to bromelain, other ingredients, or the combination.
• Sprains. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A preliminary clinical study in patients with a sprained ankle shows that taking a specific enzyme combination (Phlogenzym, Mucos Pharma) containing bromelain 90 mg, trypsin 48 mg, and rutin 100 mg, or taking different combinations of the individual enzymes three times daily for 10 days, is no more effective for relieving pain than placebo (99473).
• Tendinopathy. Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with Achilles tendon insertional tendinopathy shows that taking two sachets of a specific supplement (Tenosan, Agave, Prato, Italy) containing a total of bromelain 100 mg, arginine-L-alpha-ketoglutarate 1000 mg, methylsulfonylmethane (MSM) 1100 mg, hydrolyzed collagen type I 600 mg, vitamin C 120 mg, and Vinitrox 25 mg orally for 60 days improves function and pain when compared with placebo (19321).
• Urinary tract infections (UTIs). Oral bromelain has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that a combination of bromelain 50 mg and trypsin 1 mg (Kimotab, Mochida Pharmaceutical), taken in a dose of 8 tablets daily for 2 days, does not improve subjective symptoms of UTIs when compared with placebo (18282).
• Venous leg ulcers. Although there has been interest in using topical bromelain for venous leg ulcers, there is insufficient reliable information about the clinical effects of bromelain for this condition.
• Wound healing. It is unclear if enzymatic debridement with bromelain improves the healing of various types of chronic wounds. Details: A meta-analysis of 12 small clinical studies shows that topical bromelain reduces time to complete debridement by around 6 days but has no effect on time to healing when compared with a control (113513). However, the validity of these effects is limited by significant publication bias and a small number of studies per outcome. One small clinical study, included in the analysis above, of patients with chronic wounds related to diabetes, surgery, trauma, or venous insufficiency shows that use of bromelain-based enzymatic debridement (EscharEx, MediWound Ltd), administered as up to ten daily applications of 4 hours each, increases the incidence of complete debridement over the next 6 months to 55% of patients, compared with only 29% of those using the bromelain-free gel. However, there was no difference in changes in wound area, non-viable tissue area, or the incidence or time to complete wound closure (108148). More evidence is needed to rate bromelain for these uses.

(Read more about BROMELAIN)

EFFECTIVE

• Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
• Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
• Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
• Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

• Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
• Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
• Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
• Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

• Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
• Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
• Hypertension. Oral calcium seems to reduce blood pressure by a small amount in adults with or without hypertension. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies, including a meta-analysis of 18 high-quality clinical trials, show that intake of calcium supplements or dietary calcium modestly reduces systolic blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as those who are salt-sensitive or have low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221,113920,113925). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplemental sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367). Research evaluating the effect of calcium supplementation during pregnancy on the child's blood pressure has yielded conflicting findings. A systematic review of 2 clinical studies and 3 observational studies found that calcium intake during pregnancy is associated with a 1-2 mmHg reduction in the systolic blood pressure of the offspring between the ages of 1-7 years (38852). However, a separate meta-analysis of 3 clinical studies shows that calcium intake during pregnancy does not reduce systolic or diastolic blood pressure in the offspring (113923).
• Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
• Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia, especially in high-risk individuals and those with low baseline dietary calcium intake. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces the risk of pre-eclampsia (973,1833,8828,39043,39319,39426,97348,113919). A large clinical trial of 11,000 pregnant individuals in India and Tanzania shows that supplementation with 500 mg daily is similarly effective to 1500 mg daily (113908). Multiple meta-analyses which include 16-30 clinical studies have found that varying doses of calcium supplementation reduce the relative risk of pre-eclampsia by 46% to 51% when compared with placebo (97348,113909,113919). One of these meta-analyses found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (97348). Additionally, one of these meta-analyses found that calcium reduces the relative risk of pre-eclampsia by 51%, regardless of whether it is taken at a dose above or below 1000 mg daily (113919). Some research suggests that calcium supplementation may have a greater effect in individuals at high risk of pre-eclampsia or with low baseline dietary calcium intake, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,97348,99714,113919). However, another meta-analysis of 30 clinical studies found a similar benefit of calcium in both high- and low-risk individuals (113919). A separate meta-analysis of 6 clinical studies conducted in China evaluated the benefits of calcium carbonate 500-600 mg daily taken in conjunction with aspirin 50-75 mg daily during pregnancy. This combination was associated with an 80% lower relative risk of pre-eclampsia and an 83% lower relative risk of pre-eclampsia with gestational hypertension when compared with routine care (113913). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely (102366). Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low (97347).
• Pregnancy-induced hypertension. Oral calcium may reduce the risk of pregnancy-induced hypertension. Details: A meta-analysis of 17 clinical studies shows that calcium supplementation during pregnancy may reduce the relative risk of pregnancy-induced hypertension by 30% when compared with control (113909). A separate meta-analysis of 6 clinical studies conducted in China, which evaluated the benefits of calcium carbonate 500-600 mg daily taken in conjunction with aspirin 50-75 mg daily during pregnancy, shows that this combination reduces the relative risk of pregnancy-induced hypertension by 85% when compared with routine care (113913).
• Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
• Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

• Breast cancer. Oral calcium, via supplementation or as part of the diet, does not seem to be beneficial for breast cancer prevention. Details: Although some studies disagree (15631,39041,95811,107237,113917), most population research suggests that increased calcium intake is not associated with overall breast cancer risk (15631,16715,98895,107236,107237,113917). However, one meta-analysis of observational studies shows that although higher total calcium intake is not associated with breast cancer risk, higher dietary calcium intake, specifically, may be associated with a slightly reduced risk (113917). Also, some analyses suggest that calcium intake may be associated with the risk for certain breast cancer sub-types. Some subgroup analyses suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237) and that dietary calcium intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
• Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: Robust meta-analyses of mostly large, high-quality clinical studies show that calcium supplementation 500-1600 mg daily for 0.5-7 years with or without vitamin D does not reduce total fractures, hip fractures, vertebral fractures, or non-vertebral fractures in older adults without osteoporosis (95822,112486). A large-scale study in postmenopausal females aged 50-79 years who were enrolled in the Women's Health Initiative (WHI) suggests that calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the WHI study found that, in older females with the lowest genetic susceptibility to low BMD, taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
• Obesity. Oral calcium does not seem to improve weight loss in adults or children with overweight or obesity. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905,113918), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). A meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
• Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308,113584).

INEFFECTIVE

• Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
• Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
• Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
• Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
• Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
• Brain tumor. It is unclear if dietary calcium intake is associated with risk of brain tumor. Details: A meta-analysis of 4 case-control studies has found that higher dietary calcium intake is associated with a lower odds of brain tumor when compared with lower dietary intake (113922). The validity of this finding is limited by the exploratory nature of the included studies, which analyzed all dietary ingredients for any potential associations.
• Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
• Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
• Diabetes. It is unclear if dietary calcium intake is associated with type 2 diabetes risk. Details: Some population research has found that a higher intake of calcium from the diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473,113929). One meta-analysis of cohort and cross-sectional studies found that the highest level of dietary calcium intake is associated with an 18% relative reduction in risk of type 2 diabetes when compared with the lowest level of intake. A dose-response analysis suggests that each 300, 600, and 1000 mg per day increase in dietary calcium intake is associated with a 7%, 14%, and 23% reduced risk of type 2 diabetes, respectively (113929). However, population research is often limited by confounding variables. For example, one analysis suggests that any beneficial effect might be influenced by concomitant magnesium intake (96473,113929), while another suggests that any benefit from increased intake may be more pronounced in females, adults aged 50 years or older, and Asian populations (113929). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis (95815).
• Dyslipidemia. It is unclear if oral calcium is beneficial for dyslipidemia. Details: One clinical study in adults with mild to moderate hypercholesterolemia shows that adding calcium carbonate 400 mg three times daily to a low-fat diet (American Heart Association Step 1) for 6 weeks reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% when compared with the low-fat diet and placebo (2557). In contrast, a clinical study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years INCREASES total cholesterol levels and carotid intima-media thickness in postmenopausal, but not premenopausal, females when compared with placebo (97350). Calcium supplementation has also been evaluated in combination with vitamin D. A meta-analysis of randomized controlled trials including adults with normolipidemia and dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is most beneficial in patients with dyslipidemia at baseline (107227). The relationship between dietary calcium intake and serum lipid levels has also been evaluated in observational research. A meta-analysis of 7-11 observational studies found that dietary calcium intake is not associated with total cholesterol levels, although small differences in individual lipid parameters were identified. Additionally, a meta-analysis of 4-9 observational studies suggests that calcium intake is not associated with the risk of developing hypertriglyceridemia, hypercholesterolemia, or low HDL. A subgroup analysis found that higher calcium intake may be associated with lower triglyceride levels in Asian populations (113927). Overall, these findings are limited by significant heterogeneity and the cross-sectional nature of the included studies.
• Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
• Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
• Exercise-induced muscle damage. It is unclear if oral calcium is beneficial for reducing exercise-induced muscle damage. Details: A very small clinical study in resistance-trained adults shows that taking calcium carbonate 500 mg 4 times daily for 3 weeks does not attenuate exercise-induced muscle damage from bench presses when compared with placebo (113933). This study may have been inadequately powered to detect a difference between groups.
• Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
• Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
• Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
• Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
• Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
• Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
• Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
• Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
• Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
• Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
• Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
• Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
• Prematurity. It is unclear if supplemental calcium is beneficial for the growth and development of preterm infants. Details: A small clinical study in preterm infants consuming human milk shows that supplementation with calcium 45 mg/kg daily and phosphorus 25 mg/kg daily does not affect infant weight, length, head circumference, or risk of osteopenia after 6 weeks when compared with human milk alone (113924). However, the duration and size of this study may have been too limited to detect any difference between groups.
• Preterm labor. It is unclear if oral calcium reduces the risk of preterm labor. Details: A meta-analysis of 10 clinical studies shows that taking calcium supplements during pregnancy does not reduce the risk of preterm labor when compared with placebo (113909). A separate meta-analysis of 7 clinical studies conducted in China, which evaluated the benefits of calcium carbonate 500-600 mg daily taken in conjunction with aspirin 50-75 mg daily during pregnancy, shows that this combination reduces the relative risk of preterm labor by 74% when compared with routine care (113913).
• Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
• Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
• Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

(Read more about CALCIUM)

POSSIBLY EFFECTIVE

• Chronic venous insufficiency (CVI). Oral grape leaf extract might improve CVI symptoms. It is unknown if other grape products are beneficial for CVI. Details: Some clinical trials in patients with CVI show that taking a specific grape leaf extract, known as red vine leaf extract (AS 195, Antistax, Boehringer Ingelheim), seems to improve leg edema after 6 weeks of treatment when compared with placebo. Doses of 360 mg and 720 mg daily were both effective, but the higher dose produced a slightly greater effect. Patients also reported decreases in subjective complaints such as tired or heavy legs, tension, and tingling and pain after 2-12 weeks of treatment (2538,52985,53005,53206).

POSSIBLY INEFFECTIVE

• Allergic rhinitis (hay fever). Oral grape seed extract does not seem to improve hay fever symptoms. Details: A clinical study in patients with seasonal allergic rhinitis shows that taking grape seed extract 100 mg twice daily for 8 weeks before ragweed pollen season does not seem to decrease seasonal allergic rhinitis symptoms or antihistamine usage when compared with placebo (9182).
• Chemotherapy-induced nausea and vomiting (CINV). Drinking grape juice does not seem to improve CINV. Details: Clinical research shows that taking 4 ounces of chilled Concord grape juice 30 minutes prior to meals for a week following each of four cycles of chemotherapy does not seem to reduce CINV when compared with placebo (53175).
• Lower urinary tract symptoms (LUTS). Drinking grape juice does not seem to improve LUTS. Details: Clinical research in middle-aged and older men with LUTS shows that drinking 100% Concord grade juice 240 mL daily for 3 months does not improve symptoms when compared with placebo (96190).
• Mastalgia. Oral grape seed extract does not seem to improve mastalgia symptoms. Details: Clinical research in patients treated for early breast cancer using high-dose radiotherapy shows that taking the grape seed extract constituent proanthocyanidin 100 mg orally three times daily for 6 months does not reduce breast tissue hardness, pain, or tenderness when compared with placebo (53048).
• Obesity. Oral grape products do not seem to improve weight loss. Details: Clinical research in overweight or obese individuals shows that drinking Concord grape juice 480 mL daily for 12 weeks does not improve weight or body composition when compared to baseline (53181). Furthermore, taking grape pomace alone or in combination with schisandra fruit extract daily for 4-10 weeks does not improve body composition, abdominal fat, or body weight when compared with control (96200,99269,99270). Taking grape pomace 7-8 grams daily for 4-6 weeks seems to improve insulin resistance by about 33%, but does not affect blood lipids or blood pressure, when compared with placebo in overweight or obese adults with at least one metabolic syndrome factor (99269,99270).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Oral grape skin extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in adults with signs of aging skin shows that taking a specific combination product (Celergen, Laboratories-Dom) containing grape skin extract 10 mg, marine collagen peptides 570 mg, coenzyme Q10 10 mg, luteolin 10 mg, and selenium 0.05 mg, one capsule with breakfast and dinner for 2 months, might improve skin elasticity when compared with baseline. However, there was no effect on moisture or biological skin age (97930). It is not clear if these effects are due to grape skin extract, the other ingredients, or the combination.
• Age-related macular degeneration (AMD). Although there is interest in using oral grape seed for AMD, there is insufficient reliable information about the clinical effects of grape for this condition.
• Atherosclerosis. Oral grape seed extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in postmenopausal adults shows that taking a specific combination product (Karinat, INAT-Farma) containing grape seed extract constituent proanthocyanidin 40 mg, garlic 100 mg, hops 160 mg, green tea 115 mg, vitamin C 30 mg, silicon 8 mg, vitamin E 6.6 mg, and beta-carotene 0.5 mg three capsules daily for 12 months might slow the progression of atherosclerosis as measured by mean carotid intima thickness when compared with placebo. However, the combination product does not seem to affect the growth of existing plaques, and it does not seem to improve lipid parameters (97929). It is not clear if these effects are due to grape seed extract, the other ingredients, or the combination.
• Athletic performance. It is unclear if oral grape products are beneficial for athletic performance. Details: A small study in elite athletes shows that taking a specific grape extract (Powergrape, Naturex SA) 400 mg daily for one month can increase total power in a jumping task when compared with placebo, but has no effect on initial power and maintenance of power (53310). Another small study in recreationally active young adults shows that drinking juice prepared from 46 grams of a freeze-dried preparation of whole grapes daily for 6 weeks prior to a running exercise test does not improve maximal oxygen uptake or work capacity during exercise when compared with placebo (91540).
• Atopic dermatitis (eczema). Topical grape products have only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with atopic dermatitis shows that twice daily application with a cream containing grape polyphenols, vitamin E, and epigallocatechin gallate for 28 days does not improve symptoms or reduce the affected area based on physician assessment when compared with placebo (96196).
• Attention deficit-hyperactivity disorder (ADHD). Although there is interest in using oral grape seed for ADHD, there is insufficient reliable information about the clinical effects of grape for this condition.
• Canker sores. Although there is interest in using oral grape seed for canker sores, there is insufficient reliable information about the clinical effects of grape for this condition.
• Cardiovascular disease (CVD). It is unclear if oral grape products are beneficial for reducing CVD risk. Details: There is preliminary evidence that taking grape products, such as purple grape juice or red grape juice concentrate, might improve endothelium-dependent vasodilation, prevent low-density lipoprotein (LDL) oxidation, reduce markers of inflammation, and suppress platelet-mediated thrombosis. Theoretically, chronic ingestion of these products might reduce the risk of CVD in various patient populations, including adults with type 2 diabetes or hypercholesterolemia, those undergoing hemodialysis, and children with metabolic syndrome (8745,8746,52954,53030,53062,53106,53155,53174). However, a large meta-analysis shows that although taking grape products, including grape extract, grape juice, raisins, and grape seed extract, reduces levels of blood fats by a small amount in a mixed population of adults, these effects were not present in a subgroup of patients with CVD when compared with placebo. There was a small benefit on total cholesterol and high-density lipoprotein (HDL) cholesterol (102610).
• Cognitive function. It is unclear if oral grape products improve cognitive function. Details: Clinical research in healthy adults aged 55-75 years with no cognitive decline shows that taking a specific grape fruit extract (Cognigrape, Bionap srl) 250 mg daily for 12 weeks improves cognitive functioning by 4.5%, and overall neuropsychological status, including attention, language, and recall, by 6%, compared with no change in the placebo group (96198). Also, a preliminary clinical study in middle-aged women under moderate stress shows that drinking Concord grape juice 355 mL daily for 12 weeks improves immediate spacial memory and may improve executive function and verbal recall when compared with placebo (96195).
• Cognitive impairment. Small clinical studies suggest that oral grape products may not slow cognitive decline in older patients with cognitive impairment. Details: One very small study in in patients with mild cognitive decline shows that taking a freeze-dried grape powder 36 grams twice daily for 6 months does not improve most measures of cognitive function and memory, including immediate memory, delayed memory, speed of information processing, cognitive ability, or language, when compared with placebo (96199). Another very small study in older adults with signs of memory decline shows that drinking 100% Concord grape juice 6-9 mL/kg daily for 12 weeks does not improve delayed verbal recall or spatial memory when compared with placebo, although it does seem to moderately improve verbal learning (53166).
• Colorectal cancer. Oral grape seed extract is has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with colorectal cancer shows that taking a product containing grape seed extract, turmeric extract, fermented soybean extract, green tea extract, spirulina, and Taiwanofungus camphoratus, 1920 mg three times daily for 16 weeks during a chemotherapy regimen might modestly increase the effectiveness of treatment when compared with placebo. No patients in the treatment group experienced disease progression, compared with 15.8% (6 patients) of the placebo group. However, there was no significant effect on overall survival or the best response to treatment (96183).
• Constipation. Although there is interest in using oral grape products for constipation, there is insufficient reliable information about the clinical effects of grape for this condition.
• Dental caries. Although there is interest in using topical grape seed for dental caries, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Diabetes. Oral grape extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study of males with type 2 diabetes mellitus and erectile dysfunction suggests that an oral combination product containing alpha lipoic acid, Gingko biloba, and grape extract (Blunorm Forte, Uriach S.p.A.) taken for 3 months may decrease fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score both alone and when combined with avanafil when compared with baseline and placebo (110707).
• Diabetic retinopathy. It is unclear if oral grape seed extract is beneficial in patients with diabetic retinopathy. Details: A preliminary clinical study in patients with non-proliferative diabetic retinopathy shows that taking a specific grape seed proanthocyanidin extract (Entelon, Hanlim Pharm) 50 mg three times daily for 12 months reduces the severity of hard exudates when compared with calcium dobesilate or placebo. Grape seed extract had a treatment success rate 3-fold and 5.5-fold higher than those of calcium dobesilate and placebo, respectively. Treatment success was defined as a 2-grade decrease in hard exudate severity. No significant improvements in retinopathy grade or visual acuity were reported (100954). However, the study may not have been adequately powered to detect a difference in these outcomes.
• Erectile Dysfunction (ED). Oral grape extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large study of males with type 2 diabetes mellitus and erectile dysfunction suggests that a specific combination product containing alpha lipoic acid, grape extract, and gingko biloba (Blunorm Forte, Uriach S.p.A.) administered orally for three months with avanafil prior to sexual acts improves International Index of Erectile Function (IIEF) scores when compared with either product alone, placebo, and baseline, and may reduce markers of ED including high sensitivity-c-reactive protein, nitrates/nitrites, and metalloproteinases-2 and -9. These results suggest that an oral combination nutraceutical consisting of alpha lipoic acid, grape extract, and gingko biloba (Blunorm Forte, Uriach S.p.A.) may react synergistically with avanafil to enhance sexual performance in males with type 2 diabetes and erectile dysfunction. It is unclear if this effect is due to the alpha lipoic acid, grape extract, or gingko biloba, but researchers theorize that it may be due to the inhibition of phosphodiesterase-5 enzymes by grape extract (110707).
• Hemorrhoids. Although there is interest in using oral grape seed for hemorrhoids, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Hypercholesterolemia. Small clinical studies suggest that oral grape products reduce cholesterol levels by a small amount. Details: A large meta-analysis of heterogeneous clinical trials shows that taking grape products, including grape extract, grape juice, raisins, or grape seed extract, for 2-54 weeks reduces levels of total and low-density lipoprotein (LDL) cholesterol, as well as triglycerides, by a small amount when compared with placebo in a mixed population of adults. In a sub-group of patients with any hyperlipidemia, the mean decreases in LDL cholesterol and triglycerides were 11 mg/dL and 14 mg/dL, respectively. There was no effect on levels of high-density lipoprotein (HDL) in the mixed population or in adults with hyperlipidemia (102610). Although some individual studies disagree, the most evidence for benefit is related to use of whole grape extract or grape seed extract. It is not clear if benefit is dependent on dose or duration of use. These results suggest a benefit of grape products in patients with hypercholesterolemia, but any benefit is likely to be small (42585,96816,102610).
• Hypertension. Some research suggests that oral grape products may modestly lower blood pressure; however, results are inconsistent. Details: Some clinical trials have shown modest benefit in patients with prehypertension, mild hypertension, or metabolic syndrome (18228,53149,96197), but conflicting results exists (91541,90079). A 2016 meta-analysis including 16 trials of 810 patients shows that when compared with placebo, grape seed extract or polyphenols reduces systolic blood pressure (SBP) and diastolic blood pressure (DBP) by about 6 mmHg and 3 mmHg, respectively, with greatest improvements observed in those with obesity or metabolic syndrome. This meta-analysis suggests that a minimum treatment duration of 8 weeks may be necessary before benefit is seen (96194). However, other research in adults with hypertension shows that taking grape seed polyphenols 1000 mg daily for 6 weeks does not alter blood pressure. Also, when grape seed polyphenols were combined with vitamin C 500 mg daily, some patients experienced an increase in blood pressure and worsening of nighttime and daytime variation in blood pressure (13162,90079). The reason for these conflicting findings is unclear but may due to patient characteristics and comorbidities. A meta-analysis of clinical research in various patient populations shows that taking grape seed extract 150-2100 mg for 2-25 weeks improves DBP and heart rate when compared with control, but does not improve SBP or flow-mediated dilation, regardless of dose, duration, sex, BMI, or health status. Additionally, subgroup analyses suggest that blood pressure effects may be greater in patients who are otherwise healthy, female, overweight, and/or under 50 years of age. Also, the use of lower doses and longer treatment durations may be associated with greater benefit (108090). The validity of these findings is limited by the high heterogeneity of included studies. A clinical study in adults with mildly elevated blood pressure shows that a specific grape seed extract (Enovita; Indena SpA) standardized to provide at least 95% oligomeric proanthocyanins, taken as 150 mg twice daily for 16 weeks, does not reduce SBP or DBP when compared with placebo. However, a subgroup analysis suggests that taking grape seed extract improves blood pressure in males, but not in females, when compared with placebo (108091). Some research has also evaluated the effects of grape juice on blood pressure. Two clinical studies in patients with hypertension show that drinking grape juice can reduce blood pressure when compared to baseline; however, another study shows that drinking grape juice does not reduce blood pressure when compared with placebo in these patients (53018,53156,53199).
• Melasma. It is unclear if oral grape seed extract is beneficial in patients with melasma. Details: A very small clinical study in Japanese females with melasma shows that taking grape seed extract (Gravinol, Kikkoman Co) containing 54 mg of proanthocyanidins three times daily for 6-11 months reduces skin hyperpigmentation when compared to pretreatment (53016). The validity of this finding is limited by the lack of a control group.
• Menopausal symptoms. It is unclear if oral grape seed extract is beneficial in patients with menopausal symptoms. Details: Preliminary clinical research in adults with at least one menopausal symptom shows that taking grape seed extract (Gravinol, Kikkoman Biochemifa Co) containing proanthocyanidin 200 mg daily for 8 weeks reduces anxiety when compared with placebo. It also reduces hot flashes and other physical symptoms when compared to baseline, but not when compared with placebo. A lower dose of proanthocyanidin 100 mg daily does not appear to improve these outcomes. Neither doses improved insomnia or depression (91542).
• Metabolic syndrome. Small studies suggest that various oral grape products might improve lipid levels and blood pressure in patients with metabolic syndrome. Details: A meta-analysis of small clinical studies in adults with type 2 diabetes or metabolic syndrome shows that taking grape products, usually grape seed or grape extract, for 4-48 weeks reduces levels of total and low-density lipoprotein (LDL) cholesterol, as well as triglycerides, by a small amount when compared with placebo. The mean decreases in LDL cholesterol and triglycerides were 2.6 mg/dL and 11 mg/dL, respectively (102610). These findings are limited by significant heterogeneity of the included research. Also, a small clinical study in overweight or obese adults, most with metabolic syndrome, shows that taking grape pomace 8 grams daily for 6 weeks improves insulin resistance by about 33%, but does not affect blood lipids, blood pressure, or fasting glucose, when compared with placebo (99270). Some grape products have also shown benefit for improving blood pressure in patients with metabolic syndrome. One small clinical crossover study in males with metabolic syndrome shows that taking 46 grams daily of a freeze-dried, dehydrated preparation of grape polyphenols (equivalent to about 250 grams of fresh grapes daily) for 30 days seems to modestly lower systolic, but not diastolic, blood pressure, and increase brachial artery flow-mediated dilation (FMD) when compared with placebo (18228). Also, a small clinical study in adolescents with metabolic syndrome suggests that drinking natural grape juice 18 mL/kg daily for one month improves FMD when compared with baseline (53174).The validity of this finding is limited by the lack of a control group. A very small clinical study in patients with metabolic syndrome shows that taking a specific grape seed extract (Meganatural BP, Polyphenolics) 150-300 mg daily for 4 weeks modestly reduces blood pressure when compared with placebo (53149). The validity of this finding is limited due to small study size and because patients in the treatment groups had higher blood pressure at baseline.
• Minor bleeding. Topical grape vine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that topically applying 4 mL of a specific product (Ankaferd blood stopper) containing grape vine, alpinia, licorice, thyme, and stinging nettle reduces bleeding, but does not improve the surgical time for episiotomy repair, when compared with saline (31010). It is unclear if this effect is due to grape vine, other ingredients, or the combination.
• Muscle soreness. It is unclear if oral grape products improve muscle soreness. Details: One small study in active young adults shows that drinking juice, prepared from 46 grams of freeze-dried whole grapes, daily for 6 weeks prior to an eccentric arm exercise test does not reduce muscle inflammation or pain at 24 or 48 hours post-exercise when compared with placebo (91540).
• Night vision. Although there is interest in using oral grape seed extract for improving night vision, there is insufficient reliable information about the clinical effects of grape for purpose.
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral grape seed extract reverses fatty liver in patients with NAFLD. Details: One small clinical study in adults with NAFLD shows that taking grape seed extract 1000 mg twice daily for 3 months improves some, but not all, markers of liver damage and improves the grade of fatty liver change when compared with vitamin C supplementation (53190).
• Ocular stress. Although there is interest in using oral grape seed extract for ocular stress, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Premenstrual syndrome (PMS). Although there is interest in using oral grape seed extract for PMS, there is insufficient reliable information about the clinical effects of grape for this condition.
• Wound healing. Limited research suggests that topical grape seed extract might improve wound healing. Details: A small clinical study in adults undergoing surgical removal of minor skin lesions shows that applying red grape seed extract 2% cream twice daily to the affected areas reduces the time to complete wound healing by about 6 days when compared with a placebo cream (91539). Also, preliminary clinical research in patients recovering from cesarean section shows that applying grape seed extract 5% ointment twice daily to cesarean section wounds for 14 days improves wound healing, as measured by a scoring system assessing redness, edema, ecchymosis, discharge, and wound closure, when compared with a placebo ointment. A 2.5% ointment did not improve wound healing measures when compared with placebo (100955). More evidence is needed to rate grape for these uses.

(Read more about GRAPE)

Proteolytic enzymes represent a wide group of enzymes that are used alone or in combination. See specific monographs for effectiveness information.

(Read more about PROTEOLYTIC ENZYMES (PROTEASES))

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. It is unclear if topical rutin is beneficial for aging skin. Details: Preliminary clinical research shows that topical application of a cream containing rutin 2% twice daily for 4 weeks reduces signs of skin aging around the eye in females aged 30-50 years. Skin dermal density is improved by 20%, area of crow's feet is reduced by 26%, and the number of wrinkles under the eye is reduced by 53% when compared with placebo (92236).
• Autism spectrum disorder. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in children 4-10 years-old with autism spectrum disorder shows that taking a product containing rutin 3 mg/kg, luteolin 10 mg/kg, and quercetin 7 mg/kg daily for 26 weeks improves aspects of behavior, such as hyperactivity, irritability, and lethargy, by a moderate to large amount when compared to baseline. It also seems to improve some indices of functioning, such as daily living and social behavior, by a small amount. These improvements were considered to be greater than expected when taking aging into consideration; however, no placebo was used in this study (96765).
• Diabetes. It is unclear if oral rutin is beneficial for diabetes. Details: A small clinical study in adults with type 2 diabetes conducted in Iran shows that taking rutin 500 mg twice daily for 3 months reduces fasting blood glucose and glycated hemoglobin by approximately 40 mg/dL and 1%, respectively, and modestly reduces triglycerides and total and low-density lipoprotein cholesterol when compared with placebo (112182). The interpretation of these findings is limited by the omission of data regarding concurrent diabetes medications. A small observational study in patients with a family history of type 1 diabetes shows that taking a specific product (Mucos Pharma) containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg daily for 24 months is not associated with reduced incidence of type 1 diabetes at 8 years (99472).
• Exercise-induced respiratory infections. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in non-elite male runners shows that taking a combination product (Wobenzym Plus, Mucos Pharma) providing rutin 600-1200 mg, trypsin 288-576 mg, and bromelain 540-1080 mg daily for 3 weeks, starting one week before a marathon, does not reduce the risk of a post-race respiratory tract infection when compared with placebo (96766).
• Hemorrhoids. Although there is interest in using oral rutin for hemorrhoids, there is insufficient reliable information about the clinical effects of rutin for this condition.
• Inflammatory bowel disease (IBD). Although there is interest in using oral rutin for IBD, there is insufficient reliable information about the clinical effects of rutin for these conditions.
• Lymphedema. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some clinical research in patients who have undergone a mastectomy shows that taking a specific combination product containing rutin, pancreatin, papain, bromelain, trypsin, and chymotrypsin (Wobenzym N, Mucos Pharma) daily for 7 weeks reduces arm swelling associated with lymphedema when compared with diuretics (24560). Also, preliminary clinical research in patients with primary or secondary lymphedema of the upper or lower limbs shows that taking a combination product containing rutin 300 mg, bromelain 100 mg, and sweet clover 100 mg daily for 6 months decreases pitting, limb volume, pain, and quality of life when compared to baseline (103298). The validity of these findings is limited by the lack of a comparator group. Also, it is unclear if these effects are due to rutin, other ingredients, or the combination.
• Multiple sclerosis (MS). Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A preliminary clinical study in patients with relapsing-remitting MS shows that taking an enzyme combination containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg per tablet for at least 3 months does not affect the progression of disability, relapse rate, or central nervous system lesions when compared with placebo (99468). The validity of these results are limited by the short duration of treatment.
• Obesity. It is unclear if oral rutin is beneficial for obesity. Details: In Japanese adults with a body mass index (BMI) of 23-30 kg/m2, a small clinical trial shows that taking a specific monoglucosyl rutin ( αG Rutin PS) 200 mg or 400 mg daily for 8 weeks reduces the area of visceral fat by 2.4 cm and 3.5 cm, respectively, compared with an increase of 5.2 cm in those taking placebo. However, there were no differences between groups in the actual value of visceral fat, changes in total fat or subcutaneous fat, BMI, body weight, abdominal circumference, or cholesterol or triglyceride levels (105298).
• Oral mucositis. Although there is interest in using oral rutin for oral mucositis, there is insufficient reliable information about the clinical effects of rutin for this condition.
• Osteoarthritis. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a specific combination product (Wobenzym PS, formerly Phlogenzym, Mucos Pharma) at a dose providing up to 600 mg rutin, 288 mg trypsin, and 540 mg bromelain daily for 3-12 weeks, is as effective as diclofenac for relieving pain and improving knee function in patients with painful osteoarthritis of the knee. This product also reduces the need for rescue medication by 95% when compared with placebo (6252,91104,99467,99477).
• Postoperative swelling. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical study in patients undergoing surgery of the jaw shows that taking an enzyme combination of rutin 200 mg, trypsin 96 mg, and bromelain 180 mg twice daily for 5 days in addition to standard treatment reduces soft-tissue thickness (indicating the amount of swelling) at most of the nine assessed facial points when compared to control (99476).
• Sprains. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in patients with a sprained ankle shows that taking a specific enzyme combination (Phlogenzym, Mucos Pharma) containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg, or taking different combinations of the individual enzymes three times daily for 10 days, is no more effective for relieving pain than placebo (99473).
• Stroke. Although there is interest in using oral rutin for stroke prevention, there is insufficient reliable information about the clinical effects of rutin for this purpose.
• Sunburn. Although there is interest in using topical rutin for sunburn prevention, there is insufficient reliable information about the clinical effects of rutin for this purpose.
• Varicose veins. Although there is interest in using oral rutin for varicose veins, there is insufficient reliable information about the clinical effects of rutin for this condition. More evidence is needed to rate rutin for these uses.

(Read more about RUTIN)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Asthma. Although there has been interest in using oral serrapeptase for asthma, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Atherosclerosis. Although there has been interest in using oral serrapeptase for atherosclerosis, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Back pain. Although there has been interest in using oral serrapeptase for back pain, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Bronchiectasis. It is unclear if oral serrapeptase is beneficial in patients with bronchiectasis. Details: A small clinical study in patients with bronchiectasis shows that taking serrapeptase 30 mg orally daily for 4 weeks significantly reduces frequency of cough and also seems to decrease sputum viscosity and neutrophil counts in sputum samples when compared with no treatment (13153).
• Cardiovascular disease (CVD). Although there has been interest in using oral serrapeptase for CVD, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Carpal tunnel syndrome. Although there has been interest in using oral serrapeptase for carpal tunnel syndrome, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Chronic bronchitis. It is unclear if oral serrapeptase is beneficial in patients with chronic bronchitis. Details: A small clinical study in patients with chronic bronchitis shows that taking serrapeptase 30 mg orally daily for 4 weeks significantly reduces frequency of cough and expectoration and also seems to decrease sputum viscosity and neutrophil counts in sputum samples when compared with no treatment (13153).
• Diabetes. Although there has been interest in using oral serrapeptase for diabetes, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Fibromyalgia. Although there has been interest in using oral serrapeptase for fibromyalgia, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Fibrocystic breast disease. Although there has been interest in using oral serrapeptase for fibrocystic breast disease, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Inflammatory bowel disease (IBD). Although there has been interest in using oral serrapeptase for IBD, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Laryngitis. It is unclear if oral serrapeptase is beneficial in patients with laryngitis. Details: A clinical study in patients with acute or chronic ear, nose, or throat disorders, including laryngitis, shows that taking serrapeptase 10 mg orally three times daily reduces pain, secretions, difficulty swallowing, and body temperature after 3-4 days of treatment when compared with placebo (13152).
• Migraine headache. Although there has been interest in using oral serrapeptase for migraine headache, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Osteoarthritis. Although there has been interest in using oral serrapeptase for osteoarthritis, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Osteoporosis. Although there has been interest in using oral serrapeptase for osteoporosis, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Otitis media. Although there has been interest in using oral serrapeptase for otitis media, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Pharyngitis. It is unclear if oral serrapeptase is beneficial in patients with pharyngitis. Details: A clinical study in patients with acute or chronic ear, nose, or throat disorders, including pharyngitis, shows that taking serrapeptase 10 mg orally three times daily reduces pain, secretions, difficulty swallowing, and body temperature after 3-4 days of treatment when compared with placebo (13152).
• Postoperative swelling. It is unclear if oral serrapeptase is beneficial in patients with postoperative swelling. Details: Serrapeptase has been evaluated for reducing facial swelling after a variety of procedures. A clinical study in patients undergoing maxillary antrostomy for empyema shows that taking serrapeptase 10 mg orally three times on the day before surgery, once in the evening after surgery, and three times daily for 5 days after surgery modestly reduces buccal swelling when compared with placebo (13151). In patients requiring removal of impacted mandibular third molars, a small clinical study in healthy adults shows that taking serrapeptase 10 mg orally three times daily for 5 days improves postoperative trismus and swelling, but not pain scores, by the fourth postoperative day when compared with placebo (106013). The validity of these findings in limited by a lack of consistent comparison to baseline in both groups. Conversely, two other small studies in patients requiring removal of impacted mandibular third molars show that serrapeptase is less effective than dexamethasone or another proteolytic enzyme, consisting of trypsin, bromelain, and the flavonoid rutin, for improving swelling or facilitating wound healing (106011,106012). The validity of these findings is limited due to poor study methodologies.
• Rhinosinusitis. It is unclear if oral serrapeptase is beneficial in patients with rhinosinusitis. Details: A clinical study in patients with acute or chronic ear, nose, or throat disorders, including rhinosinusitis, shows that taking serrapeptase 10 mg orally three times daily reduces pain, nasal secretions, nasal obstruction, and anosmia after 3-4 days of treatment when compared with placebo (13152).
• Rheumatoid arthritis (RA). Although there has been interest in using oral serrapeptase for RA, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Tension headache. Although there has been interest in using oral serrapeptase for tension headache, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose.
• Venous leg ulcers. Although there has been interest in using oral serrapeptase for venous leg ulcers, there is insufficient reliable information about the clinical effects of serrapeptase for this purpose. More evidence is needed to rate serrapeptase for these uses.

(Read more about SERRAPEPTASE)

POSSIBLY EFFECTIVE

• Allergic rhinitis (hay fever). Oral turmeric seems to improve symptoms in people with allergic rhinitis. Details: A large clinical study in people with allergic rhinitis shows that taking a specific curcumin product (Organika Health Products) 500 mg daily for 2 months reduces nasal symptoms, including sneezing, itching, runny nose, and congestion, when compared with placebo (96138).
• Depression. Most research shows that oral curcumin, a constituent of turmeric, when used at doses of at least 1 gram daily for at least 6 weeks improves symptoms of depression when taken alone or in combination with antidepressant medications. Details: Curcumin appears to be most beneficial for depression in middle aged patients compared to older patients, when taken for at least 6 weeks, and when used at a dose of at least 1 gram daily. In adults with major depressive disorder, a meta-analysis of data from 6 clinical studies, as well as individual studies not included in this analysis, show that taking curcumin 1 gram daily along with an antidepressant moderately improves depression symptoms when compared with placebo (96131,96139). Another meta-analysis of 10 studies shows symptom reductions in patients with major depression when combined with conventional antidepressants, but not when used alone in patients with milder depressive symptoms. However, the quality of the evidence is low (104971). Additionally, a large clinical study in adults with mild-moderate symptoms of depression shows that taking curcumin 750 mg twice daily for 12 months modestly reduces depression symptoms when compared with placebo (114898). When used alone, one clinical study shows that curcumin 1 gram daily for 6 weeks may be similarly effective to fluoxetine 20 mg daily. Taking both products together seems to be more effective than either product alone, increasing the response rate from 65% to 78% (89728). Guidelines from The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce state that curcumin extract at doses of 500-1000 mg daily is provisionally recommended for monotherapy or adjunctive use in mild to moderate depression (110318).
• Dyspepsia. Oral turmeric may be modestly beneficial for some patients with dyspepsia. In patients with functional dyspepsia, small clinical studies show that oral curcumin, a constituent of turmeric, is similarly effective when compared with the proton-pump inhibitor omeprazole. Details: Clinical research shows that taking turmeric 500 mg four times daily for 7 days can relieve overall symptoms of dyspepsia in 64% more patients than taking placebo (11144). A small, unblinded clinical study in patients with a type of dyspepsia called postprandial distress syndrome shows that taking turmeric 250 mg or 500 mg orally three times daily after meals for 4 weeks is associated with reductions in symptom scores which are similar to those seen with simethicone 60 mg three times daily for 4 weeks. However, the recurrence rate upon stopping therapy was about 14% with simethicone, compared with 43% to 46% with turmeric (104963). In patients with functional dyspepsia, taking the constituent curcumin appears similarly effective when compared with omeprazole, but might not provide further symptom reduction in those also taking famotidine or omeprazole (106063,106801,111599). One small clinical study in Iran shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg daily in addition to famotidine 40 mg daily for 30 days is no more effective for reducing overall symptoms of dyspepsia, such as abdominal pain, heartburn, bloating, and nausea, when compared with famotidine alone (106063). Another small clinical study in Thailand shows that taking curcumin 500 mg four times daily for 4 weeks is similarly effective for reducing dyspepsia severity and improving satisfaction when compared with an unspecified dose of omeprazole and more effective when compared with placebo (106801). Similarly, a moderate-size clinical study in Thailand shows that taking curcumin 500 mg four times daily for 4 weeks is similarly effective for reducing dyspepsia severity when compared with omeprazole 20 mg daily. However, taking curcumin and omeprazole in combination did not provide further symptom reduction (111599). The validity of these results is limited by the high rate of study dropouts.
• Hyperlipidemia. Research is conflicting on whether oral turmeric, curcumin, or curcuminoids can reduce serum lipids. Any improvement in lipids is likely to be small. Reasons for the conflicting findings may relate to turmeric formulation, duration of treatment, and/or the baseline cholesterol status of the included patients. Details: Results from meta-analyses of clinical research show inconsistent and conflicting results. One large meta-analysis of over 50 clinical studies in healthy adults and those with a variety of conditions shows that supplementation with turmeric or curcumin 80-4000 mg daily for 4-24 weeks reduces total cholesterol by 4 mg/dL, low-density lipoprotein (LDL) cholesterol by 5 mg/dL, and triglycerides by 7 mg/dL and increases high-density lipoprotein (HDL) cholesterol by 2 mg/dL when compared with placebo (112119). Two other meta-analyses of 27 clinical studies agree that taking turmeric, curcumin, or curcuminoids moderately reduce triglyceride levels but suggest that turmeric does not improve total cholesterol when compared with placebo. However, the meta-analyses contradict one another on whether turmeric and its constituents reduce LDL cholesterol or increase HDL cholesterol. (96128,96135). Additionally, a third meta-analysis of 10 clinical trials shows that taking up to 2400 mg daily of curcumin or curcuminoids, from turmeric or isolated sources, for up to 12 weeks, does not significantly improve triglycerides, LDL cholesterol, HDL cholesterol, or total cholesterol (110220).
• Nonalcoholic fatty liver disease (NAFLD). Oral curcumin, a constituent of turmeric, seems to attenuate fat deposition and improve some metabolic parameters in adults with NAFLD. Details: Clinical research shows that taking curcumin daily reduces NAFLD severity in 30% to 79% of patients, compared to 5% to 27.5% of patients receiving placebo. Curcumin also reduces the quantity of additional fat deposition in the liver to 0% to 4.5%, compared to 17.5% to 26% in those taking placebo. Most research shows that taking curcumin also reduces liver enzyme levels, body mass index (BMI), blood glucose levels, glycated hemoglobin (HbA1c), and total cholesterol when compared with placebo. Although some clinical research shows that taking curcumin improves levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides, a meta-analysis of clinical research shows that these lipid levels are not improved in patients with NAFLD, specifically (97430,97431,100258,102350,106062,107120,109279,111349,114901). However, another meta-analysis of 14 small, heterogeneous clinical studies in adults with NAFLD, that included some of these studies, shows that taking various doses and forms of turmeric or curcumin modestly reduces liver enzyme levels, improves measures of insulin resistance, reduces waist circumference, and improves LDL, HDL, and triglyceride levels when compared with placebo (111348). A small clinical trial in patients with NAFLD given specific lifestyle recommendations shows that taking curcumin modestly reduces the frequency of metabolic syndrome and fatty liver but does not have beneficial effects on fatty liver-associated indices, adiposity, or the atherogenic index, when compared with placebo (109285). Findings for specific endpoints are mixed between individual studies and may depend on the dose and formulation of curcumin used or the duration of treatment. These studies have used various doses and formulations. In one study, 500 mg of a dispersion formulation equivalent to 70 mg of curcumin daily for 8 weeks was used (97430). Also, 250 mg once daily or 500 mg twice daily of a specific phytosomal formulation (Meriva, Indena) containing curcumin and soy phosphatidylcholine in a 1:2 ratio and standardized to an overall curcuminoid content of 20% was taken for 8 weeks (97431,106062). Another study used 1 gram of powdered turmeric rhizome taken three times daily with meals for 12 weeks (102350). One study used a curcumin-piperine complex (Curcumin C3 complex 500 mg plus Bioperine 5 mg) daily for 8 weeks (107120). One study used curcumin (Arjuna Natural Extract) 500 mg three times daily for 12 weeks (109285). Despite positive results with curcumin in several small clinical studies of patients with NAFLD, there is some concern that curcumin might cause hepatotoxicity in rare cases, especially when highly bioavailable formulations are used in high doses (103633). There is also evidence that the risk for hepatotoxicity with curcumin may be increased in individuals with the HLAB*35:01 allele (109288). Curcumin-induced hepatotoxicity has not been reported in clinical trials of patients with NAFLD, and its potential mechanism is unclear. However, patients seeking to take curcumin for NAFLD should be advised to monitor for symptoms of hepatotoxicity, including abdominal pain, dark urine, fatigue, jaundice, nausea, and pruritus.
• Oral mucositis. Oral curcumin or curcumin-containing mouthwash seem to reduce the development of severe oral mucositis, as well as reduce the severity and pain of oral mucositis, associated with cancer treatment. Details: Clinical research in patients receiving radiotherapy following recent radical surgery for oral cancer shows that taking turmeric (BCM-95, Arjuna Natural Pvt. Ltd., India) during radiotherapy reduces the incidence of severe oral mucositis to 25% or 20% in those taking turmeric 500 mg two or three times daily, respectively, compared with 65% in those taking placebo. The incidences of severe oral pain, dysphagia, and dermatitis were also reduced by at least 50% (105398). A small clinical study in patients receiving chemotherapy with or without head and neck radiotherapy shows that taking a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina) 80 mg twice daily for 7 weeks improves severity of oral mucositis at weeks 1, 4, and 7 and reduces pain at week 7 when compared with placebo. Effects were more pronounced in those with chemotherapy-induced oral mucositis than radiotherapy-induced oral mucositis (106800). In patients with head and neck cancer receiving radiotherapy, preliminary clinical research shows that swishing with 10 mL of turmeric solution (prepared by dissolving turmeric 400 mg in 80 mL of water) six times daily for 6 weeks delays mucositis and reduces the number of cases of intolerable mucositis by 49% when compared to swishing with 10 mL of povidone-iodine solution twice daily for 6 weeks (89726). Another small clinical study shows that swishing with 10 mL of nanoparticulate curcumin 0.1% mouthwash three times daily for 6 weeks is associated with a 50% lower risk of developing oral mucositis, and a delay of 2 weeks in the onset of mucositis, when compared with benzydamine 0.15% mouthwash (104969). A small clinical study in patients with mucositis due to head and neck radiotherapy shows that taking curcumin nanoparticles (SinaCurcumin, ExirNanoSina) 40 mg daily or using 10 mL of a curcumin 0.1% mouthwash three times daily for up to 21 days improves scores related to pain, burning, ulceration, and erythema when compared with placebo. Results with either oral or topical curcumin were similar (111350).
• Osteoarthritis. Some oral turmeric extracts and combination products containing turmeric seem to improve certain symptoms of knee osteoarthritis. However, it is unclear how turmeric compares to the use of non-steroidal anti-inflammatory drugs (NSAIDs). Details: Several meta-analyses of clinical studies show that turmeric extracts and/or curcuminoid products reduce knee pain and stiffness, improve physical function, and reduce the need for rescue medication when compared with placebo (104970,106792,109280,110222). However, a reduced effect was noted in patients with increasing age or body mass index (104790). The studies evaluated in these meta-analyses are heterogeneous, of low- to moderate-quality, and utilized a variety of products and/or dosing strategies (104970,106792,109280,110222). Small to moderate-sized clinical studies show that specific products (Meriva, Indena; Theracurmin, Theravalues Corp) containing curcumin 90-100 mg twice daily for up to 6 months, or specific turmeric extracts (Turmacin, Natural Remedies Pvt. Ltd.; Curcugen, DolCas Biotech, LLC) 500 mg twice daily for 6-12 weeks, reduce pain and analgesic use and improve functionality when compared with placebo (17953,80988,89721,97424,104148,107118). A specific turmeric extract (CuraMed, EuroPharma USA) 1500 mg daily for 12 weeks improves functionality, but not pain, when compared with placebo (96127). Also, a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina), 40 mg twice daily for 6 weeks, improves pain, stiffness, and physical activity scores and reduces intake of rescue acetaminophen by about 60% when compared with placebo (102349). However, not all turmeric products seem to be effective for improving symptoms of osteoarthritis. One small clinical study shows that taking a specific turmeric extract (B-Turmactive, PLAMECA S.A.) 500 mg daily for one week does not reduce knee pain when compared with placebo (104147). Also, a meta-analysis of clinical research shows that benefits are limited to bio-optimized forms of curcuminoids, and benefits related to pure extracts are lacking (110222). Turmeric has also been compared with conventional treatments for knee osteoarthritis in small meta-analyses, a network meta-analysis, and individual clinical studies. However, the evidence is mixed as to whether turmeric is as effective or more effective than NSAIDs, such as ibuprofen 400 mg taken 2-3 times daily, diclofenac 25-100 mg daily, or chondroprotective drugs (17952,89720,89722,106792,109280,110222,113607). A network meta-analysis comparing 6 interventions in adults with knee osteoarthritis suggests that curcumin monotherapy, curcumin with chondroprotective agents, or curcumin with NSAIDs improves scores related to pain, function, and stiffness while reducing the need for rescue medication and the incidence of adverse events (113607). Individual studies are heterogenous with respect to comparator medication and dosing schedule. Doses included a non-commercial turmeric extract 500 mg 3-4 times daily for 4-6 weeks (17952,89720) or turmeric extract 500 mg twice daily for 3 months (89722). Topical turmeric has also been evaluated. One clinical study shows that applying curcumin topically as a 5% ointment in Vaseline twice daily for 6 weeks reduces pain associated with knee osteoarthritis by a mean of about 11 on a 100-point visual analog scale when compared with placebo (104964). Another clinical study in patients with knee osteoarthritis shows that applying curcumin in a self-nano-emulsifying polyethylene glycol organogel 1.5 grams to the knee twice daily for 8 weeks reduces pain, stiffness, and difficulty with physical function scores by 72%, 62%, and 46%, respectively, when compared to baseline, with improvements superior to placebo for all outcomes (113357). Research also shows that taking specific combination products containing turmeric and other ingredients can improve pain and functionality in patients with osteoarthritis. These combination products have combined turmeric with chondroitin sulfate and glucosamine hydrochloride (CartiJoint Forte, Fidia Farmaceutici SpA); boswellic acid (Curamin, EuroPharma USA; Rhulief); Boswellia serrata (Rhulief); ashwagandha, Boswellia serrata, and zinc (Articulin-F, Eisen Pharmaceutical Co. Pvt. Ltd.); devil's claw and bromelain (AINAT, Laboratoire de Rhumatologie Appliquée); Boswellia serrata, guggul, and valerian (Phytoproflex, OPTM Healthcare); Boswellia serrata and terminalia (LI73014F2, Laila Nutraceuticals); ashwagandha, Boswellia serrata, and ginger (Artrex, Mendar); or extracts of ginger rhizome, devil's claw tuber, Boswellia serrata resin, and celery seed (Tregocel, Max Biocare) (19276,51950,81466,89717,89719,96127,97419,97421,97428,106078)(109280).
• Pruritus. Oral turmeric has been evaluated for the management of pruritus of various etiologies, with promising results. Details: Clinical research in patients with kidney failure shows that taking turmeric 500 mg orally three times daily for 8 weeks decreases symptoms of uremic pruritus by 1.9-fold when compared with placebo (89724). Also, a small clinical study in patients with sulfur mustard-induced chronic pruritus shows that taking a specific combination product (C3 Complex, Sami Labs LTD) containing curcumin 1 gram plus extract from black pepper or long pepper (Bioperine) daily for 4 weeks reduces pruritus severity and improves quality of life when compared with placebo (81120,81176).

POSSIBLY INEFFECTIVE

• Alzheimer disease. Neither oral turmeric nor its constituent curcumin appears to improve cognitive function or attenuate cognitive decline in adults with this condition. Details: A small clinical trial shows that taking the turmeric constituent, curcumin, 1-4 grams daily for 6 months does not improve mental state examination scores when compared with placebo (17096). Furthermore, a meta-analysis of this study and another small clinical study in patients with Alzheimer disease shows that the turmeric group experienced greater cognitive decline when compared with placebo (100261). While this research is limited by small study sizes and heterogeneous patient populations, the current evidence does not support the use of turmeric in patients with this condition.
• Peptic ulcers. Oral turmeric does not seem to improve the healing of peptic or gastric ulcers when compared with placebo or liquid antacids. Details: Some clinical research shows that taking turmeric 2 grams three times daily for 8 weeks does not improve the healing of peptic ulcers when compared with placebo in Vietnamese patients (81444). Also, taking powdered turmeric rhizome 250 mg four times daily for 6 weeks seems to be less effective than a liquid aluminum-magnesium-hydroxide antacid for promoting gastric ulcer healing (81284).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there has been interest in using topical turmeric for acne, there is insufficient reliable information about the clinical effects of turmeric for this purpose.
• Age-related cognitive decline. Some small clinical studies suggest that oral curcumin, a constituent of turmeric, may modestly improve cognition in elderly patients experiencing cognitive decline. Details: A meta-analysis of three small clinical trials shows that curcumin modestly improves cognition in the elderly (100261). One of these clinical trials shows that taking a specific brand of curcumin (Theracurmin, Theravalues Corp.) 90 mg twice daily for 18 months improves long-term memory and attention when compared with placebo in middle-aged and older adults with or without mild cognitive impairment (96161).
• Amenorrhea. Although there has been interest in using oral turmeric for amenorrhea, there is insufficient reliable information about the clinical effects of turmeric for this purpose.
• Ankylosing spondylitis. Although there has been interest in using oral turmeric for ankylosing spondylitis, there is insufficient reliable information about the clinical effects of turmeric for this purpose.
• Anxiety. Some clinical research show that oral curcumin reduces symptoms of anxiety. Details: A meta-analysis of 8 mostly low-quality clinical studies in adults with anxiety symptoms or an anxiety disorder diagnosis shows that taking curcumin 500-1000 mg daily for up to 12 weeks modestly reduces symptoms of anxiety when compared with placebo (114902). The validity of the meta-analysis is limited by the heterogeneity of the included studies, including differences in the patient populations, form and doses curcumin, treatment durations, and types of anxiety scales used. Additionally, all studies were conducted in either Iran or Australia which may limit generalizability of results to other populations.
• Aromatase inhibitor-induced arthralgia. It is unclear if oral curcumin, a constituent of turmeric, is beneficial for aromatase inhibitor-induced arthralgia. Details: A small clinical trial in patients experiencing aromatase inhibitor-induced arthralgia shows that taking curcuminoids as a nanoemulsion (Curcumin C3 Complex, Sabinsa Corporation) 200 mg daily for 3 months does not improve grip strength or joint symptoms when compared with placebo (113345). However, this study may have been underpowered to detect a difference between groups.
• Asthma. Some small clinical studies suggest that oral turmeric, as an adjunct to conventional asthma treatment, does not improve lung function or symptoms in adults and children with asthma. Details: One small clinical study in adults with mild to moderate asthma shows that adjuvant therapy with turmeric as curcumin 500 mg twice daily for 30 days does not improve lung function based on FEV1, or improve symptoms such as dyspnea, wheezing, cough, or tightness, when compared to standard treatment alone (99349). A small clinical trial in children 7-18 years of age with moderate to severe asthma shows that adding turmeric 500-1000 mg (containing 20-40 mg curcuminoids) daily for 6 months to standard therapy does not improve overall asthma symptoms when compared with placebo and standard therapy, although it may decrease the frequency of nighttime awakenings and the use of rescue inhalers (99348). Due to their small sizes and high drop-out rates, these studies may have been underpowered to detect a difference between groups.
• Athletic performance. It is unclear if oral curcumin, a constituent of turmeric, is beneficial for athletic performance. Details: Preliminary clinical research in middle-aged male long-distance runners shows that taking a turmeric extract providing 2 grams of curcumin 95% and piperine 5% daily for 6 weeks does not improve aerobic capacity when compared with placebo (109286).
• Benign prostatic hyperplasia (BPH). It is unclear if oral curcumin, a constituent of turmeric, is beneficial in BPH. Details: A clinical study in patients with BPH shows that taking curcumin 2250 mg once daily along with tamsulosin and finasteride for 6 months improves lower urinary tract symptoms related to storage, but not overall symptoms or symptoms related to voiding, by about 35%, compared with 25% in those receiving tamsulosin and finasteride alone. Periprostatic fat thickness, quality of life, and erectile function also were improved (106799).
• Beta-thalassemia. It is unclear if oral turmeric is beneficial for iron overload in patients with beta-thalassemia. Details: A small clinical study in patients with beta-thalassemia major and iron overload shows that taking turmeric extract containing curcumin 500 mg twice daily for 12 weeks modestly reduces non-transferrin bound iron (NTBI) by 0.6 micromol/L, but not hemoglobin, transferrin saturation, total iron binding capacity, ferritin, or hepcidin, when compared with placebo (99306). Another small clinical study in adult males with beta-thalassemia intermedia and iron overload shows that taking a higher dose of curcumin 500 mg three times daily for 12 weeks modestly reduces serum iron and ferritin turmeric levels and transferrin saturation when compared with placebo (108871).
• Bruises. Although there has been interest in using topical turmeric to alleviate bruising, there is insufficient reliable information about the clinical effects of turmeric for this purpose.
• Cachexia. It is unclear if oral curcumin, a constituent of turmeric, is beneficial for cancer cachexia. Details: A small clinical trial in patients with cancer anorexia-cachexia syndrome shows that taking curcumin 800 mg twice daily for 8 weeks does not reduce weight loss or improve body composition or handgrip strength when compared with placebo (109283).
• Canker sores. Some preliminary research suggests that topical curcumin, a constituent of turmeric, is beneficial for minor canker sores. Details: Preliminary clinical research in young adults with minor canker sores shows that applying a 2% curcumin oral gel for 6 months reduces ulcer size, pain, and recurrence rate and increases healing rate similarly to 0.1% triamcinolone oral paste (104962). The validity of the study is limited by a lack of investigator blinding and the lack of an intention to treat analysis. Another small clinical study shows that applying a 1% curcumin nanomicelle gel (SinaCurcumin Pharmaceuticals) on lesions three times daily for one week is modestly more effective than applying a 2% curcumin gel for reducing pain and ulcer size (109282). The validity of this finding is limited by the lack of a non-curcumin comparator group.
• Carpal tunnel syndrome. Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is unclear if topical curcumin, a constituent of turmeric, is beneficial for carpal tunnel syndrome. Details: A moderate-sized clinical study in adults with mild to moderate carpal tunnel syndrome shows that taking a combination product containing turmeric, alpha-lipoic acid, acetyl-L-carnitine, phosphatidylserine, and vitamins C, E, B1, B2, B6, and B12 twice daily for 60 days reduces symptom severity and pain but does not improve measures of hand and wrist function when compared with control (111702). The validity of these effects is limited by a lack of blinding. The study may also be inadequately powered to detect a difference between groups. Additionally, it is unclear if the effects are due to turmeric, other ingredients, or the combination. Topical turmeric has also been investigated. A small clinical study in patients with mild to moderate carpal tunnel syndrome shows that applying a 1% curcuminoid gel (Sinanomin) to the wrists twice daily for 8 weeks modestly decreases symptom severity and improves function when compared with a placebo gel. However, there was no change in electrodiagnostic testing of the injury. All patients also used a night splint (113356).
• Chemotherapy-induced acral erythema. It is unclear if oral or topical turmeric reduces the risk for acral erythema from capecitabine. Details: A small clinical trial in adults with cancer shows that taking turmeric 4 grams daily for 6 weeks starting at the beginning of treatment with capecitabine does not reduce the incidence of acral erythema overall; however, it does seem to reduce acral erythema grade 2 or higher when compared with expected incidence rates (99309). Topical turmeric has also been evaluated. A clinical study in patients with colorectal, gastric, pancreatic, or breast cancer receiving capecitabine shows that applying a specific ointment (Alpha) standardized to contain curcumin extract 0.5% and henna extract 10% to the soles and palms twice daily, beginning on day 1 of chemotherapy and continued for 4 cycles, does not prevent acral erythema or improve World Health Organization severity scores when compared with placebo. A post-hoc analysis suggests that there may have been a trend toward delayed onset and progression; however, this study was not structured to assess these outcomes (108874).
• Chemotherapy-induced constipation. It is unclear if oral curcumin reduces symptoms of chemotherapy-induced constipation. Details: A small clinical study in patients with various forms of cancer receiving standard chemotherapy for that cancer type shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg twice daily for 9 weeks does not reduce symptoms of constipation when compared with placebo (107111).
• Chemotherapy-induced diarrhea. It is unclear if oral curcumin reduces symptoms of chemotherapy-induced diarrhea. Details: A small clinical study in patients with various forms of cancer receiving standard chemotherapy for that cancer type shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg twice daily for 9 weeks does not reduce symptoms of diarrhea when compared with placebo (107111).
• Chemotherapy-induced nausea and vomiting (CINV). It is unclear if oral curcumin reduces CINV. Details: A small clinical study in patients with various forms of cancer receiving standard chemotherapy for that cancer type shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg twice daily for 9 weeks modestly reduces symptoms of nausea, but not vomiting, in the second and third months after the start of treatment when compared with placebo (107111).
• Chemotherapy-induced peripheral neuropathy. It is unclear if oral curcumin reduces symptoms of chemotherapy-induced peripheral neuropathy. Details: A small clinical study in patients with various forms of cancer receiving standard chemotherapy for that cancer type shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg twice daily for 9 weeks modestly reduces symptoms of chemotherapy-induced peripheral neuropathy over a three-month period when compared with placebo (107111).
• Chronic kidney disease (CKD). It is unclear if oral turmeric is beneficial for CKD. Details: A meta-analysis of four small clinical trials in patients with CKD related to diabetic nephropathy or lupus nephritis shows that taking curcumin or turmeric for 0.5-4 months moderately reduces proteinuria when compared with placebo (109276). Also, a small clinical trial in children and young adults ages 6-25 years with vascular dysfunction related to autosomal dominant polycystic disease (PKD) shows that curcumin powder 25 mg/kg daily for 12 months does not improve vascular function or kidney function when compared with placebo (107117).
• Colorectal adenoma. It is unclear if oral turmeric is beneficial for managing colorectal adenoma. Details: Preliminary clinical research in adults with familial adenomatous polyposis shows that taking curcumin 1500 mg twice daily for 12 months does not reduce the quantity or size of lower intestinal adenomatous polyps when compared with placebo (97427). A very small clinical trial in patients with familial adenomatous polyposis shows that taking 8 capsules daily of a turmeric extract, in a formulation also containing pepper fruit, spirulina, seaweed, and ginger root, for 6 months does not affect total polyp number or burden when compared with placebo. However, both number and burden were modestly reduced in the left colon. Each capsule provided curcuminoids 123.65 mg and turmerones 26.79 mg (110223).
• Colorectal cancer. It is unclear if oral turmeric is beneficial for the prevention or treatment of colorectal cancer. Details: A small clinical trial in patients undergoing chemotherapy following colorectal cancer surgery shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg daily for 8 weeks modestly improves some measures of quality of life when compared with placebo (107109). In addition, a small clinical study in people at high risk for colorectal cancer, such as those who smoke, shows that taking the turmeric constituent, curcumin, 4 grams daily for 30 days can reduce the number of precancerous rectal aberrant crypt foci (18204). It is not clear if this results in a reduced risk for colorectal cancer.
• Coronary artery bypass graft (CABG) surgery. One small study suggests that oral turmeric may reduce the risk for myocardial infarction after CABG surgery. Details: Preliminary clinical research shows that taking the turmeric constituent, curcuminoids, 4 grams daily in four divided doses, beginning 3 days prior to surgery and continuing for 5 days post-surgery, decreases the relative risk of myocardial infarction following CABG by approximately 56% when compared with placebo (81143).
• Coronavirus disease 2019 (COVID-19). It is unclear if oral turmeric or its constituent, curcumin, is beneficial for reducing symptoms of COVID-19. Details: Small studies have evaluated curcumin as an adjunctive therapy in adults hospitalized with confirmed COVID-19. Patients in these studies also received treatments such as antimicrobials, anti-inflammatory medications, anticoagulants, antiretrovirals, and immunosuppressants (104966,105393,107119). One study shows that adding curcumin reduces the duration of shortness of breath by 6-9 days when compared with patients who received other treatments in combination with probiotics. However, there were no differences in the duration of other symptoms, including fever, cough, or sore throat. Subgroup analyses suggest that taking curcumin may improve oxygenation and reduce the need for supplemental oxygen or ventilation (105393). Another study shows that adding curcumin modestly reduces the time to resolution of COVID-19 symptoms, the length of supplemental oxygen use, and the likelihood for deterioration in the patients' condition when compared with patients who received other treatments alone (104966). A third study shows some benefit of curcumin on fever and cough when compared with baseline; however, it is unclear if any changes were significant when compared with placebo (107119). Doses of curcumin used in these studies include curcumin 525 mg with piperine 2.5 mg (C3 Complex, SamiDirect) twice daily, starting at admission and continuing for 14 days (105393), or a specific nanocurcumin product (SinaCurcumin, ExirNanoSina) 80 mg twice daily for 2 weeks or 240 mg daily in divided doses for 7 days (104966,107119). Limitations of these studies include the small number of patients with severe symptoms, the large number of outcomes evaluated, the inconsistencies in other treatments used, the lack of clarity related to presentation of some results, and, in most cases, a lack of blinding. Turmeric has also been evaluated in adults in the outpatient setting with suspected or confirmed mild to moderate COVID-19. One small clinical study shows that taking curcumin (SinaCurcumin, ExirNanoSina) 80 mg twice daily for 14 days in addition to other COVID-19 treatments (mainly hydroxychloroquine and azithromycin) reduces the duration of cough, chills, myalgia, and smell and taste disturbance, but not dyspnea, fever, sore throat, or others, by 1-2 days when compared with placebo with other treatments (106802). The validity of this study is limited by the lack of confirmatory diagnosis at baseline and lack of consistency with other treatments, as well as the unclear reporting of symptom duration in relation to the initiation of treatment. Another small clinical study in outpatients confirmed to have COVID-19 shows that taking curcumin 1000 mg plus piperine 10 mg (Sami Labs Limited) daily for 14 days modestly improves weakness, but not cough, pain, headache, difficulty breathing, or biochemical indices, when compared with placebo (109278). However, a clinical study in adults with confirmed asymptomatic or mild COVID-19 shows that taking curcumin (curcuRouge®, TheraBioPharma) 360 mg twice daily for 7 days within 5 days of COVID-19 diagnosis does not reduce the risk of fever or oxygen saturation below 96% when compared with placebo (114905). Some research has also examined the effect of turmeric as part of a polyherbal combination. Clinical research in patients hospitalized for moderate COVID-19 symptoms shows that using an Ayurvedic formulation 1776 mg twice daily containing turmeric, ashwagandha, ginger, and Boswellia serrata (BV-4051) for 14 days modestly reduces the duration of illness and reduces the severity of fever, cough, and smell and taste dysfunction when compared to placebo. There was no beneficial effect on other symptoms, including nasal congestion, breathing difficulty, headache, and gastrointestinal symptoms. More than half of the patients were also treated with remdesivir which did not impact the majority of these findings (109899).
• Crohn disease. It is unclear if oral turmeric is beneficial for improving symptoms of active Crohn disease. Details: Some clinical research shows that taking the turmeric constituent, curcumin, 1.08 grams daily for one month, then 1.44 grams daily for one month, can reduce bowel movements, diarrhea, and abdominal pain when compared to baseline in patients with Crohn disease (79730). The validity of these findings is limited by the lack of a comparator group.
• Denture stomatitis. Topical turmeric may be beneficial for treating denture stomatitis. Details: A small clinical study in patients with denture stomatitis shows that applying topical curcumin gel (Curenext, Abbott Laboratories) three times daily for 2 weeks resolves denture stomatitis lesions similarly to clotrimazole ointment (106797).
• Diabetes. Lower quality clinical studies suggest that oral curcumin, a constituent of turmeric, may modestly improve glycemic control in patients with diabetes. Details: A meta-analysis of small clinical trials in patients with diabetic kidney disease shows that curcumin reduces levels of fasting glucose by approximately 8.3 mg/dL when compared with placebo. Curcumin was used in doses of 66.3-1670 mg daily for 2-6 months (107114). Preliminary clinical research included in the analysis shows that taking a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina) 80 mg daily for 12 weeks reduces fasting blood glucose by about 20 mg/dL (104149). Other meta-analyses of low- to moderate-quality clinical studies in patients with a variety of conditions including type 2 diabetes show that taking turmeric extract, curcumin, or curcuminoids for 4-36 weeks improves glycated hemoglobin (HbA1c) by 0.4-0.7% and reduces fasting glucose by approximately 13 mg/dL when compared with placebo or conventional treatment (106806,108877,113604). The validity of these findings is limited by the heterogeneity of the included studies and broad curcuminoid doses ranging from 46-1500 mg daily. Conversely, other meta-analyses in patients with type 2 diabetes show that curcumin does not reduce HbA1c or insulin levels when compared with placebo (104965,108877,113604).
• Diabetic foot ulcers. It is unclear if oral curcumin is beneficial in patients with diabetic foot ulcers. Details: Preliminary clinical research in patients with grade 3 diabetic foot ulcers shows that taking nanocurcumin 80 mg orally daily for 12 weeks does not improve glycated hemoglobin (HbA1c) or change the rate of ulcer healing when compared with placebo. Taking turmeric did result in modest decreases in fasting blood glucose, insulin levels, and insulin resistance (104972).
• Diabetic nephropathy. It is unclear if oral curcumin is beneficial in patients with diabetic nephropathy. Details: Meta-analyses of two to four small clinical trials in patients with diabetic kidney disease show that curcumin modestly improves serum levels of creatinine, total cholesterol, and fasting glucose, and reduces systolic blood pressure by 4 mmHg, when compared with placebo. However, there was no effect on diastolic blood pressure, proteinuria, or serum levels of other plasma lipids or blood urea nitrogen. Curcumin was used in doses of 66.3-1670 mg daily for 2-6 months (107114). One small study included in this analysis, which evaluated patients receiving hemodialysis, shows that taking a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina) 80 mg daily for 12 weeks reduces fasting blood glucose by about 20 mg/dL when compared with placebo (104149).
• Dysmenorrhea. Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in university students aged 18 to 24 in Iran with mild to severe primary dysmenorrhea and premenstrual syndrome (PMS) shows that taking a specific combination product containing curcumin 500 mg plus extract from black pepper 5 mg (C3 Complex, Sami Labs) daily, starting 7 days prior to menstruation and continuing for 3 days after menstruation for 3 consecutive menstrual cycles, does not improve the severity of symptoms when compared with placebo (106805). Conversely, a small clinical study in adults with moderately painful dysmenorrhea shows that taking a single dose of a combination product containing turmeric, Boswellia serrata, and sesame (Rhuleave-K, Arjuna Natural Private Ltd.) 1000 mg at the start of menstruation relieves menstrual cramp pain and reduces pain intensity for up to 6 hours when compared with placebo (112806). However, it is unclear if these effects are due to turmeric, other ingredients, or the combinations.
• Endometriosis. It is unclear if oral turmeric is beneficial for reducing pain due to endometriosis. Details: A small clinical study in adults with endometriosis shows that taking the turmeric constituent, curcumin, 500 mg twice daily for 8 weeks does not affect pain associated with endometriosis or quality of life when compared with placebo (113603).
• Erythema. Although there has been interest in using topical turmeric for reducing erythema, there is insufficient reliable information about the clinical effects of turmeric for this purpose.
• Exercise-induced muscle damage. It is unclear if oral curcumin, a constituent of turmeric, is beneficial for reducing muscle damage from exercise. Details: A meta-analysis of 12 small, lower-quality clinical studies in adults shows that taking curcumin 150-500 mg as a single dose before or after exercise or 180-5000 mg daily for up to 56 days reduces markers of muscle damage (i.e. serum creatine kinase levels) when compared with placebo. Curcumin seems most beneficial for this effect in untrained adults and when administered as a single dose. Additionally, a meta-analysis of 3 of these clinical studies shows that curcumin improves range of motion (114897). The interpretation of these findings is limited by significant heterogeneity.
• Exercise-induced muscle soreness. It is unclear if oral turmeric or its constituent, curcumin, is beneficial for reducing muscle soreness from exercise. Details: A meta-analysis of 12 small, lower-quality clinical studies in trained and untrained adults shows that taking curcumin 150-500 mg as a single dose before or after exercise or 180-5000 mg daily for up to 56 days time reduces muscle soreness when compared with placebo. Subgroup analysis indicated that the largest effect size is observed at 96 hours post-exercise with progressively smaller effect sizes at earlier time points (114897). The interpretation of these findings is limited by significant heterogeneity. Turmeric has also been examined in combination with other ingredients. Clinical research in healthy active adults with moderate to severe exercise-induced muscle pain shows that taking a single, 1000-mg dose of turmeric and Boswellia serrata extracts in black sesame oil (Rhuleave-K; Arjuna Natural Private Ltd.) improves pain relief when compared with placebo, with maximal benefits within about 3 hours. The number of people needed to treat to obtain pain relief of at least 50% over a 6-hour period was 1.1 (109277).
• Gingivitis. Small clinical studies suggest that oral turmeric and turmeric mouthwash may reduce the severity of gingivitis. Turmeric mouthwash appears to be similarly effective to chlorhexidine mouthwash. Details: A meta-analysis of generally preliminary clinical research shows that rinsing with a mouthwash containing curcumin for 3-4 weeks is as effective as rinsing with chlorhexidine for reducing the severity of gingivitis or plaque (106059). Mouthwashes in these studies contained 0.05% to 20% curcumin and were usually used twice daily for 3-4 weeks (81127,89723,106059). One mouthwash contained 0.05% turmeric extract and 0.005% eugenol (89723). Another small clinical trial shows that taking a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina) 80 mg daily by mouth after breakfast for 4 weeks reduces the severity of gingivitis and gingival bleeding, but not plaque, when compared with placebo in patients with gingivitis and mild periodontitis (104146).
• Gout. Although there is interest in using oral turmeric for gout, there is insufficient reliable information about the clinical effects of turmeric for this condition.
• Gulf war syndrome. It is unclear if oral curcumin is beneficial in patients with Gulf war syndrome. Details: A small preliminary clinical trial in patients with Gulf war syndrome shows that taking curcumin (Meriva, Indena, S.p.A.) 500 mg twice daily for 30 days reduces overall symptoms, including pain, fatigue, gastrointestinal distress, and others, by 19% when compared with baseline. Taking a higher dose of 2000 mg twice daily for an additional 30 days appears to be no more effective than the lower dose (105395).
• Hearing loss. It is unclear if oral turmeric is beneficial for treating hearing loss. Details: A small clinical study in adults with mild to moderate hearing impairment shows that taking curcumin 500 mg daily for 12 weeks improves some measures of auditory function, such as auditory brain stem response threshold, when compared with placebo (114906).
• Helicobacter pylori. Small clinical studies suggest that oral turmeric is not beneficial for eradicating H. pylori when used alone or in combination with standard triple therapy or famotidine. Details: One small clinical study in patients with H. pylori gastritis shows that taking turmeric 2.1 grams daily for 4 weeks is less effective for eradicating H. pylori than taking an omeprazole-based triple regimen for one week (80957). Another small study in adults with peptic ulcers shows that taking a specific curcumin product (C3 Complex, Sami Labs LTD) 500 mg daily for 7 days, in conjunction with standard triple therapy, does not improve H. pylori eradication rates when compared with standard triple therapy alone. The addition of curcumin increased the resolution of dyspepsia symptoms by an additional 21%, but the clinical significance of this outcome is unclear (97420). In patients with dyspepsia, most of whom tested positive for fecal H. pylori antigen, clinical research shows that taking curcuminoids (C3 Complex, Sami Labs) 500 mg with piperine (Bioperine) 5 mg daily in addition to famotidine 40 mg daily for 30 days is no more effective for reducing fecal H. pylori antigen levels than taking famotidine alone (106063).
• Hypertension. It is unclear if oral curcumin is beneficial in patients with hypertension. Details: A meta-analysis of approximately 30 clinical studies in healthy adults or patients with a variety of conditions shows that taking turmeric, curcumin, curcuminoids, or nano-curcumin for 4 to 24 weeks reduces systolic blood pressure by about 2 mmHg and diastolic blood pressure by about 0.8 mmHg when compared with placebo (113602). However, these blood pressure reductions may not be clinically meaningful. In addition, most of the included studies were small and utilized heterogeneous dosing regimens.
• Impaired glucose tolerance (prediabetes). Oral turmeric may modestly improve glucose control in some patients with prediabetes. Details: In overweight or obese individuals with prediabetes, clinical research shows that taking a turmeric extract (BCM95 or Cucugreen; M/s Arjuna Natural Pvt Ltd.) 500 mg daily, providing 95% curcuminoids and at least 65% curcumin, for 90 days, either alone or in combination with zinc 30 mg as zinc gluconate, results in a small reduction in fasting glucose and glycated hemoglobin (HbA1c) when compared with placebo. There was also a small benefit in insulin sensitivity (105391). Other preliminary clinical research in adults with prediabetes shows that taking 500 mg of a combination of turmeric extract and Indian gooseberry extract in a 1:2 ratio along with phosphatidylcholine (EmbliQur) twice daily for 6 months modestly reduces fasting glucose and improves insulin resistance, when compared with placebo. However, changes in most other endpoints were not significantly different from placebo. Each 500 mg capsule contained turmeric extracts 29.86% and turmeric oil 1.27% (113355). The effect of turmeric on progression to type 2 diabetes in patients with prediabetes has also been investigated. Preliminary clinical research shows that taking a turmeric extract containing curcumin 750 mg twice daily for 9 months reduces the percentage of patients with prediabetes who develop type 2 diabetes when compared with placebo (81163).
• Irritable bowel syndrome (IBS). It is unclear if oral turmeric is beneficial for improving symptoms of IBS. Details: Preliminary clinical research in otherwise healthy adults with IBS shows that taking a turmeric extract (Cynara Turmeric, Lichtwer Pharma) 72-144 mg daily for 8 weeks reduces IBS symptoms by about 40% to 60% when compared to baseline (79565). The validity of this finding is limited by the lack of a comparator group. Taking a combination product (CU-FEO, Alfa Wasserman S.p.A.) containing curcumin 42 mg and fennel essential oil 25 mg per capsule twice daily for 60 days improves overall ratings of abdominal pain, abdominal distention, and quality of life by 24% when compared with placebo (97422). It is unclear if these effects are due to turmeric, fennel, or the combination. Observational research suggests that adding a supplement (Enterofytol PLUS) providing curcumin 42 mg and berberine 200 mg twice daily for 2 months to conventional IBS treatment is associated with improvements in symptoms, such as abdominal discomfort, distension, and stool status, by up to 48% when compared with conventional treatment alone. Use of the supplement was also associated with a 64% reduced need for conventional treatments (113354).
• Joint pain. Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking capsules of a specific combination product (Instaflex Joint Support, Direct Digital) containing glucosamine sulfate 1500 mg, methylsulfonylmethane 500 mg, white willow bark extract 250 mg, ginger root concentrate 50 mg, Boswellia extract 125 mg, turmeric root extract 50 mg, cayenne 40 m H.U. 50 mg, and hyaluronic acid 4 mg in three divided doses daily for 8 weeks reduces joint pain severity by 37% compared to only 16% with placebo. However, it does not improve joint stiffness or function when compared with placebo (89560). It is unclear if these effects are due to turmeric, other ingredients, or the combination.
• Juvenile idiopathic arthritis (JIA). Although there is interest in using oral turmeric for JIA, there is insufficient reliable information about the clinical effects of turmeric for this condition.
• Knee pain. It is unclear if oral turmeric is beneficial for knee pain. Details: Clinical research in individuals with knee pain not related to existing arthritis shows that taking turmeric extract (TurmXTRA 60N; Inventia Healthcare Ltd. and Laila Nutraceuticals) 250 mg, providing 60% curcuminoids, once daily for 90 days modestly reduces pain associated with walking 80 meters when compared with placebo. The time taken to walk 80 meters and to climb nine steps was reduced by 4-5 seconds (105396).
• Lichen planus. Evidence is conflicting on whether turmeric is beneficial for lichen planus. Details: A meta-analysis of several small, heterogeneous, mostly low-quality clinical and observational studies in adults with oral lichen planus shows that oral or topical curcumin with or without corticosteroids for 2-12 weeks does not improve erythema, lesion size, or pain when compared with control (113605). Similarly, a network meta-analysis of small clinical trials in patients with oral lichen planus shows that applying topical turmeric gel does not improve symptoms, clinical resolution, clinical scores, or reduce pain when compared with other available interventions (111640). However, small individual clinical studies have shown some benefit in using turmeric for lichen planus. A small clinical study shows that taking a specific turmeric extract (Curcumin C3 Complex, Sabinsa Corporation) containing curcuminoids 6000 mg daily in three divided doses for 12 days can reduce erythema and ulceration associated with lichen planus when compared with placebo (81109). Another small clinical study shows that taking a nanocurcumin product (SinaCurcumin, ExirNanoSina) 80 mg orally once daily for 1 month reduces oral lichen planus lesion size, pain, and burning similarly to prednisolone 10 mg taken orally once daily for 1 month (104961).
• Metabolic syndrome. It is unclear if oral turmeric is beneficial for metabolic syndrome. Details: Research is conflicting on how turmeric, curcumin, and other formulations affect various measures of metabolic syndrome. Some clinical research and a meta-analysis of 13 clinical studies in patients with metabolic syndrome show that taking turmeric or curcumin decreases low-density lipoprotein (LDL) cholesterol, waist circumference by 2 cm, fasting blood glucose by 9 mg/dL, and diastolic blood pressure by 3 mmHg and increases high-density lipoprotein (HDL) cholesterol by 5 mg/dL when compared with placebo. However, other research shows that turmeric or curcumin have no effect on body weight, lipids, blood pressure, or blood glucose when compared with placebo (98999,99311,105400,109284,111347,112118). The validity of these effects is limited by high heterogeneity within the included studies and incomplete information about randomization and blinding. Studies have used turmeric, curcumin, and curcumin extract 80-2400 mg, in divided doses, daily for 4-12 weeks, nano-curcumin 80 mg daily for 12 weeks, or calebin A (CurCousin, Sabinsa), which is a constituent of turmeric, 25 mg twice daily for 3 months (98999,99311,105400,109284,111347,112118). Also, taking crude or phosphorylated curcuminoids 1 gram daily for 6 weeks does not improve sleep or reduce weight in these patients (105397).
• Migraine headache. It is unclear if oral curcumin is beneficial for migraine headache. Details: A small clinical trial in females with regular migraines shows that taking curcumin 500 mg twice daily for 8 weeks reduces the severity and duration, but not the frequency, of migraine headaches when compared with placebo. In individuals taking curcumin, the duration of headache per month was reduced by approximately 10.3 hours from baseline (107116).
• Myocardial infarction (MI). It is unclear if oral curcumin is beneficial for reducing myocardial injury following a MI. Details: Clinical research in patients with an acute MI shows that taking curcuminoids 500 mg plus piperine (Bioperine) 5 mg daily (Sami Labs) for 8 weeks does not improve ejection fraction, serum levels of cardiac troponin 1, blood pressure, levels of fasting blood glucose, or kidney function parameters when compared to placebo. However, there were some modest benefits on levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, glycated hemoglobin, and certain liver enzymes such as aspartate aminotransferase (AST) and alkaline phosphatase (ALP) (107115). The validity of this study is limited by its short duration and relatively small sample size.
• Obesity. Oral turmeric might modestly improve weight loss, although any effect is unlikely to be clinically significant. Details: Multiple meta-analyses of small, mostly low-quality clinical studies in adults with a variety of comorbid conditions show that taking various forms and doses of turmeric or curcumin results in an average weight loss of about 0.6-1 kg, a decrease in body mass index (BMI) of about 0.2-0.5 kg/m2, and a decrease in waist circumference of about 1.3 cm when compared with control (102345,111351,111352). A sub-analysis of dose and duration shows that a reduction in waist circumference only occurs with curcumin daily doses above 1000 mg, and duration of treatment longer than 8 weeks (102345).
• Oral submucous fibrosis. Small studies suggest that topical or oral curcumin might be beneficial for oral submucous fibrosis. However, the research is heterogenous with respect to outcomes, comparators, and the turmeric preparations, doses, and routes of administration utilized. Details: A meta-analysis of 3 small clinical trials shows that turmeric modestly improves mouth opening when compared with control. In addition, a systematic review of 11 studies shows that turmeric improves overall symptoms, including mouth opening, tongue protrusion, burning sensation, and cheek flexibility. However, studies were small with short duration and used variable dosing strategies. Most trials have studied oral turmeric 300-400 mg, either alone or with black pepper 100 mg or piperine 5 mg, for 3-6 months. Less commonly, turmeric was provided in lozenge form (105399). Also, a network meta-analysis suggests that the turmeric constituent curcumin with or without piperine is most the effective for reducing tongue protrusion when compared indirectly with various medical and antioxidant therapies; however, this analysis suggests that curcumin does not rank among the most effective interventions for improving mouth opening, burning sensation, or cheek flexibility (113514). Other preliminary clinical research shows that taking a specific oral product containing curcumin 300 mg and piperine 5 mg (Turmix tablets, Sanat Products), three times daily for 12 weeks, improves mouth opening, burning sensation, and tongue protrusion when compared with baseline, but not when compared with an antioxidant product containing alpha-lipoic acid, beta-carotene, copper, lycopene, selenium, and zinc. Mouth opening is further improved by concurrent use of a mouthwash (Turmix mouthwash, Sanat Products), containing 0.1% w/v turmeric extract (standardized to 95% curcumin), with thymol, eucalyptol, clove oil, mentha oil, and tea tree oil, twice daily for 12 weeks (102347). A small clinical study shows that applying topical curcumin gel (Curenext, Abbott Laboratories) 5 mg daily in 3-4 divided doses for 6 weeks, in combination with oral physical therapy, improves mouth opening similarly to using an aloe vera gel in combination with oral physical therapy. However, decreases in burning sensation are greater with aloe gel than curcumin gel (104967). It is not clear whether the gels, oral physical therapy, or the combination of both is responsible for the outcome. Finally, clinical research shows that applying a paste providing turmeric and holy basil 10 grams each, mixed in 10 mL of honey, to the oral mucosa 4 times daily for 3 months modestly improves mouth opening, tongue protrusion, and burning sensation and reduces the presence of fibrous bands when compared with taking a vitamin B supplement. There was no effect on the shape of the uvula (113325).
• Pain (acute). Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with acute musculoskeletal pain shows that taking a specific combination product containing turmeric and Boswellia serrata extracts in black sesame oil (Rhuleave-K; Arjuna Natural Private Ltd.) 1000 mg daily for 7 days is as effective as acetaminophen 1000 mg daily for pain relief, onset of pain relief, and onset of maximal pain relief (109287). This study is limited by its lack of blinding and placebo control. Additionally, the dose of acetaminophen used in this study is below the standard recommended daily dose.
• Periodontitis. There is limited evidence on the oral or topical use of turmeric or its constituent curcumin in patients with periodontitis. Details: A meta-analysis of heterogenous clinical studies in patients with chronic periodontitis suggests that use of local delivery gel products, usually turmeric 2% or a specific product containing curcumin (Curenext), modestly reduces pocket depth when compared with routine products, such as chlorhexidine. However, limited research suggests that curcumin products do not affect plaque or gingivitis measures, and curcumin irrigation does not affect pocket depth based on limited research (107108). A small preliminary clinical study in patients with severe chronic periodontitis shows that placing curcumin gel 2 mg on one side of the mouth along with scaling and root planing (SRP) reduces plaque and probing pocket depth, but not gingival index, when compared with SRP alone (101339). The use of oral curcumin has also been investigated. A small clinical trial in patients with gingivitis and mild periodontitis shows that taking a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina) 80 mg daily after breakfast for 4 weeks reduces the severity of gingivitis and gingival bleeding, but not plaque, when compared with placebo (104146).
• Physical performance. It is unclear if oral turmeric may be beneficial for improving physical performance in older adults. Details: A very small clinical study in moderately functioning, sedentary adults over age 65 with low-grade chronic inflammation shows that that taking a specific turmeric extract (Curcumin C3 Complex, Sabinsa Corporation) 500 mg twice daily for 12 weeks does not improve measures of physical function, walking speed, or muscle strength when compared with placebo (111357). However, this study may have been inadequately powered to detect any possible differences between groups.
• Polycystic ovary syndrome (PCOS). Small clinical studies suggest that oral curcumin may improve some metabolic parameters in patients with PCOS, but these improvements may not be considered clinically significant. Details: Clinical research in patients with PCOS shows that taking curcumin 500 mg one to three times daily for 6-12 weeks improves some metabolic parameters (104968,105394,106795). Conversely, a small clinical study in patients aged 18 to 45 with PCOS in Iran shows that taking curcumin 1000 mg daily for 12 weeks modestly reduces fasting glucose but does not improve other metabolic parameters when compared with placebo. Taking curcumin also did not improve testosterone levels or hirsutism scores (111355). Meta-analyses show that taking curcumin modestly decreases body mass index (BMI) and improves measures of glycemic control, including fasting glucose and insulin resistance, and levels of total cholesterol when compared with placebo or metformin alone. However, effects on high-density lipoprotein (HDL) cholesterol levels were mixed and there was no effect on low-density lipoprotein (LDL) cholesterol or triglyceride levels (105394,106795,110219). Other preliminary clinical research shows that taking curcumin decreases plasma dehydroepiandrosterone and fasting plasma glucose levels when compared with placebo (104968). Some clinical research also shows that taking nano-curcumin (SinaCurcumin, ExirNanoSina) 80 mg daily for 3 months is beneficial in patients already taking metformin 1500 mg daily. Taking curcumin had modest beneficial effects on fasting insulin and insulin resistance, as well as levels of testosterone, LDL cholesterol, HDL cholesterol, and triglycerides, when compared with metformin alone. There was no effect of curcumin on body weight, fasting blood glucose, or other hormones (106060).
• Postoperative pain. Small clinical studies suggest that oral curcumin, a constituent of turmeric, may modestly reduce pain in various postoperative recovery settings. Details: One small clinical study in patients undergoing laparoscopic cholecystectomy shows that taking curcumin 2 grams daily reduces postoperative pain, fatigue, and the need for analgesics by the second postoperative week when compared with placebo (81099). In patients undergoing surgery for inguinal hernia and/or hydrocele, taking curcumin 1.2 grams daily for 5 days reduces inflammation and tenderness by the sixth postoperative day when compared with placebo (81206). Curcumin was taken in 3-4 divided doses daily in these studies. Finally, taking a single dose of curcumin 200 mg after surgical removal of impacted third molars modestly reduces acute postoperative pain when compared with taking mefenamic acid 500 mg (99305).
• Premenstrual syndrome (PMS). It is unclear if oral turmeric may be beneficial for improving symptoms of PMS. Details: Some preliminary clinical research in patients with PMS shows that taking curcumin 100 mg twice daily, starting 7 days prior to menstruation and continuing for 3 days after menstruation, improves physical, behavioral, and mood symptoms, as well as overall severity of symptoms, when compared with placebo (97433). Conversely, in university students aged 18 to 24 in Iran with mild to severe PMS and primary dysmenorrhea, a clinical study shows that taking a specific combination product containing curcumin 500 mg plus extract from black pepper 5 mg (C3 Complex, Sami Labs) daily, starting 7 days prior to menstruation and continuing for 3 days after menstruation for 3 consecutive menstrual cycles, does not improve the severity of symptoms when compared with placebo (106805).
• Prostate cancer. It is unclear if oral turmeric is beneficial for the prevention or treatment of prostate cancer. Details: One small clinical study shows that taking curcumin 1.8 grams orally three times daily for 7 days, starting 4 days prior to docetaxel and prednisone treatment and continuing for up to 6 cycles, reduces PSA levels by at least half in 59% of patients when compared to baseline. Also, all patients with measurable lesions showed at least stable disease after treatment, and 40% of patients showed partial response when compared with baseline (96132). It is unclear if the addition of turmeric is beneficial when compared with docetaxel and prednisone alone. In contrast, an additional small clinical trial shows that taking curcumin 6 grams daily for 7 days every 3 weeks, starting four days before docetaxel, does not improve PSA levels or progression-free or overall survival when compared with docetaxel alone (105392).
• Psoriasis. Evidence is limited to one small study of topical use in patients with scalp psoriasis. Details: Preliminary clinical research in adults with scalp psoriasis shows that applying a tonic of turmeric to the scalp twice daily for 9 weeks modestly improves overall symptoms and quality of life when compared with a placebo tonic (97429).
• Quality of life. Some preliminary clinical research suggests that oral curcumin might improve quality of life in patients with various chronic conditions. Details: Small or low-quality clinical trials in various patient populations show that taking curcumin improves at least some measures of quality of life when compared with placebo. Research has been conducted in patients with cancer, sulfur mustard-induced chronic pruritus, benign prostatic hyperplasia (BPH), or irritable bowel syndrome (IBS). Studies have evaluated curcumin 2250 mg once daily for 6 months, a specific combination product (C3 Complex, Sami Labs LTD) containing curcumin 500-1000 mg plus piperine (Bioperine) daily for 4-9 weeks, or a combination product (CU-FEO, Alfa Wasserman S.p.A.) containing curcumin 42 mg and fennel essential oil 25 mg per capsule twice daily for 60 days (81120,81176,97422,106799,107109,107111). Also, in patients with scalp psoriasis, applying a tonic of turmeric to the scalp twice daily for 9 weeks modestly improves quality of life when compared with a placebo tonic (97429).
• Radiation dermatitis. It is unclear if oral or topical turmeric is beneficial for reducing the severity of radiation dermatitis. Details: A meta-analysis of 4 clinical studies in patients with breast cancer shows that taking curcumin 500-2000 mg three times daily for 3-7 weeks or applying curcumin gel 500 mg three times daily for 7 weeks reduces the radiation dermatitis severity score by about 0.5 points (on a 4-point scale) when compared with placebo or other control (111354). The validity of this analysis is limited by the heterogeneity of the included studies. However, a small clinical study in patients with breast cancer shows that taking nanocurcumin 80 mg twice daily during and for up to 2 weeks after treatment does not reduce skin reaction severity overall, but does modestly reduce pain, when compared with taking placebo. Also, there was a small reduction in skin reaction severity near the end of the study. All patients also used aloe vera leaf as part of the hospital protocol (109281). Another small preliminary clinical study in head and neck cancer patients shows that a specific cream (Vicco turmeric cream, Vicco Laboratories) containing turmeric and sandalwood oil, applied 5 times daily during radiation therapy, seems to reduce frequency and severity of radiation dermatitis when compared with baby oil (99307).
• Radiation proctopathy. It is unclear if oral turmeric is beneficial for preventing proctitis or cystitis in patients receiving radiotherapy for prostate cancer. Details: A small clinical study in patients with prostate cancer shows that taking a specific nanocurcumin product (SinaCurcumin, ExirNanoSina) 120 mg daily, for 3 days before and also during a course of radiotherapy, does not reduce the occurrence of proctitis or cystitis when compared with placebo (100259). This study may have been underpowered to detect small treatment effects.
• Respiratory tract infections. Although there is interest in using oral turmeric for various respiratory tract infections, including bronchitis and the common cold, it has not been clinically evaluated.
• Rheumatoid arthritis (RA). Small clinical studies suggest that oral curcumin, a constituent of turmeric, may modestly improve some symptoms of RA. Details: Meta-analyses of small clinical trials in patients with RA show that taking curcumin alone or with other treatments modestly reduces overall RA symptoms, pain, and markers of inflammation when compared with control groups, including placebo or other treatments. However, some research shows that there is no beneficial effect on tender or swollen joint count from the limited available clinical research (109280,111358), while other research shows that there is a benefit (112117). Clinical studies have evaluated curcumin 120-1200 mg daily for 2 weeks to 3 months (11149,18205,96129). The validity of these findings is limited by the small size of the studies, and in some cases, the lack of a comparator group.
• Sarcopenia. Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in elderly patients with sarcopenia shows that taking a specific slow-release product containing turmeric, protein, carbohydrate, and fiber (Cureit, Aurea Biolabs), 500 mg orally daily for 3 months, increases handgrip strength by about 1% and distance walked before feeling tired by about 6% when compared with placebo. It also increases weightlifting capacity by about 6% from baseline, compared with a 5% decrease from baseline in those taking placebo (104973). It is unclear whether these small changes are clinically meaningful.
• Schizophrenia. Although there is interest in using oral turmeric for improving cognitive function in patients with schizophrenia, there is insufficient reliable information about the clinical effects of turmeric for this use.
• Sepsis. It is unclear if oral curcumin, a constituent of turmeric, is beneficial in patients with sepsis. Details: A small clinical trial in patients admitted to the intensive care unit (ICU) with sepsis shows that a specific nanoparticle formulation of curcumin (SinaCurcumin, ExirNanoSina), 80 mg dissolved in water and administered via gastric tube following lavage twice daily for 10 days does not affect length of ICU stay, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, blood pressure, or heart rate when compared with placebo (108873).
• Smoking cessation. Oral turmeric has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in adults with a history of smoking 5 or more cigarettes daily for at least 3 years shows that taking a specific combination product containing turmeric 50 mg, ashwagandha, Indian gooseberry, tribulus, bacopa, Albizia lebbeck, licorice, clove, ginger, cowhage, and holy basil (Smotect, Smotect India) daily for 3 months reduces the number of cigarettes smoked by approximately 3 per day when compared with placebo. This product also reduces levels of alveolar carbon monoxide and carboxyhemoglobin but does not improve lung capacity (112115). However, only data from patients who completed treatment were analyzed, which limits the validity of this study. It is unclear if these effects are due to turmeric, other ingredients, or the combination. A moderate-sized clinical study in adults with a history of smoking 5 or more cigarettes daily for at least 3 years shows that taking a specific combination product containing turmeric 100 mg, ashwagandha, Indian gooseberry, tribulus, bacopa, Albizia lebbeck, licorice, clove, ginger, cowhage, and holy basil (Smotect, Smotect India) twice daily for 3 months reduces the number of cigarettes smoked by approximately 3 per day when compared with placebo. This product also reduces levels of alveolar carbon monoxide and carboxyhemoglobin but does not improve lung capacity (112115). However, only data from patients who completed treatment were analyzed, which limits the validity of this study. It is unclear if these effects are due to turmeric, other ingredients, or the combination.
• Stress. It is unclear if oral turmeric is beneficial for reducing occupational stress in healthy adults. Details: A small clinical trial in healthy adults with occupational stress-related anxiety and fatigue shows that taking a specific type of turmeric (CurQfen, Akay Flavours and Aromatics Pvt Ltd.) that contains fenugreek dietary fiber for improved bioavailability at a dose of 500 mg twice daily for 30 days reduces stress and fatigue and improves quality of life when compared with placebo, and also when compared with a standard curcumin supplement with lower bioavailability (99308).
• Stroke. It is unclear if oral turmeric is beneficial for stroke. Details: A small clinical study conducted in Iran in adults with a recent ischemic stroke shows that taking curcumin 500 mg and piperine, a pepper constituent, 5 mg (Sami Lans, India) daily for 12 weeks reduces carotid intima-media thickness, triglycerides, total cholesterol, and systolic and diastolic blood pressure, but does not improve low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or quality-of-life indicators when compared with placebo (113601). The validity of this study is limited by the lack of statistical adjustment for multiple comparisons which can lead studies to erroneously show differences between treatment groups.
• Systemic lupus erythematosus (SLE). There is limited evidence on the oral use of turmeric in adults with lupus nephritis. Details: Preliminary clinical research in adults with lupus nephritis shows that taking turmeric 1.5 grams daily in three divided doses for 3 months reduces systolic blood pressure and improves kidney function when compared to baseline (81104). The validity of this finding is limited by the lack of a comparator group.
• Tuberculosis. It is unclear if oral turmeric is beneficial in patients receiving treatment for tuberculosis. Details: A small clinical study in adults receiving antituberculosis treatment shows that taking a formulation containing turmeric 0.5 grams and Tinospora cordifolia 0.5 grams twice daily for 4 months can reduce levels of Mycobacterium tuberculosis in the sputum and improve lesion healing when compared with antituberculosis treatment alone. Also, liver toxicity associated with the antituberculosis treatment seems to be reduced when administered with this formulation (80424). It is unclear if these effects are due to turmeric, Tinospora cordifolia, or the combination.
• Ulcerative colitis. It is unclear if oral or rectal turmeric, or its constituent, curcumin, is beneficial in adults with ulcerative colitis. Details: Although two small clinical studies in adults with ulcerative colitis show that taking oral turmeric extract 2-3 grams daily for 1-6 months improves the rate of remission and reduces relapse rate (79966,97423), a meta-analysis of these studies and one additional clinical study shows that turmeric does not improve remission rates when compared with placebo (99000). A specific product (Cur-Cure, Bara Herbs Inc) was used in some of these studies. Reasons for the conflicting findings are unclear, but may be due to small patient populations, concerns about blinding, and the inclusion of patients who were also taking immunomodulating drugs. It may also be due to differences in how a study measures remission. A meta-analysis of small clinical studies in patients with mild to moderate ulcerative colitis shows that adding oral curcumin 0.5-3 grams daily to standard treatment for 1-6 months may improve clinical remission rates, but not endoscopic remission rates, when compared with placebo (108872). However, the validity of this finding is limited by the small number of studies that evaluated endoscopic remission. A small clinical study shows that administering an enema form of turmeric extract (NCB-02, Himalaya Drug Company) as 20 mL, containing turmeric extract 140 mg, daily for 8 weeks increases response rate from 50% to about 93% and increases remission rate from about 31% to 71% when compared with placebo in patients with active ulcerative colitis. However, patients using the turmeric extract enema for shorter durations did not improve when compared with placebo (89729). Turmeric has also been investigated in combination with the Mediterranean diet. A small clinical trial shows that taking curcumin (VeNatura Curcumin Supplement) 800 mg twice daily while following the Mediterranean diet for 8 weeks is no more effective for improving ulcerative colitis symptom severity than following the Mediterranean diet without supplemental curcumin (113339).
• Uveitis. It is unclear if oral curcumin is beneficial for uveitis. Details: Observational research in patients with acute non-infectious uveitic macular edema shows that taking a specific hydrophilic curcumin product (Cucrcuwin, Diabec, Alfa Intes) 60 mg twice daily for 6 months, in conjunction with standard corticosteroid treatment, and then alone for an additional 6 months, modestly improves best corrected visual acuity, but not macular thickness or intraocular pressure, when compared with standard treatment alone for 6 months (107110).
• Wound healing. Although there is interest in using topical turmeric for wound healing, there is insufficient reliable information about the clinical effects of turmeric for this condition. More evidence is needed to rate turmeric for these uses.

(Read more about TURMERIC)

EFFECTIVE

• Vitamin C deficiency. Oral or intramuscular vitamin C is effective for preventing or treating vitamin C deficiency. Details: Administering vitamin C orally or intramuscularly prevents and treats vitamin C deficiency, including scurvy. Vitamin C administration can reverse complications of scurvy within 2 days to 3 weeks (4844). In newborns with transient tyrosinemia due to vitamin C deficiency, oral or intramuscular vitamin C can correct this condition (15).

POSSIBLY EFFECTIVE

• Anemia of chronic disease. Oral vitamin C seems to improve markers of anemia in patients on hemodialysis. Details: Meta-analyses of clinical research in hemodialysis patients with anemia shows that treatment with vitamin C 200-300 mg three times weekly for 3-6 months increases hemoglobin levels by approximately 0.9 grams/dL, increases transferrin saturation by about 8%, and decreases the required recombinant human erythropoietin dose by 17 U/kg weekly when compared with standard care (83447,83475).
• Atrial fibrillation. Oral and intravenous vitamin C seems to help prevent atrial fibrillation after cardiac surgeries. Details: Meta-analyses of clinical research show that taking vitamin C prior to and after cardiac surgery reduces the risk of postoperative atrial fibrillation by 27% to 53%. Most studies administered vitamin C at doses of 1-2 grams orally daily for 1-3 days prior to cardiac surgery, followed by 1-2 grams in two divided doses daily for 4-5 days after cardiac surgery. Some studies provided vitamin C intravenously at similar doses, but oral vitamin C seems to be more effective (91233,96703,96705). Despite these findings, a meta-analysis of clinical research conducted only in the U.S. does not support the benefit of vitamin C for reducing postoperative atrial fibrillation (96703). These differences may be related to lifestyle factors such as nutrition, as well as differences in hospital treatments. Vitamin C has also been studied in combination with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with evidence of benefit (90701).
• Bowel preparation. Powdered vitamin C is approved for use as part of a polyethylene glycol-based bowel preparation for colonoscopy. Details: Clinical research shows that treatment with 2 liters of oral solution containing polyethylene glycol (PEG) plus vitamin C achieves a similar quality of bowel cleansing as treatment with 4 liters of PEG when administered on the evening prior to colonoscopy or when administered in a split-dose regimen. Patients given 2 liters of PEG plus vitamin C solution also have better adherence and experience fewer adverse events, such as nausea, vomiting, or abdominal bloating, compared to patients treated with 4 liters of PEG solution without vitamin C (90413,90415,90420,90424,90428). This treatment also appears to be effective and tolerable in elderly patients aged 60-79 years, including those with poor bowel habits and a high number of comorbidities (108085). Other clinical research in older adults undergoing bowel preparation for colonoscopy also shows that taking 1 liter of PEG plus vitamin C (CleanViewAL, Taejoon Pharm) results in similar quality of bowel cleansing overall and per segment with similar tolerability and adverse effects as sodium picosulfate 170 mL plus magnesium citrate or oral sulfate solution alone (111297,112476). The most common PEG plus vitamin C preparation used in clinical research is MoviPrep (Norgine BV), which contains macrogol 3350 100 grams, sodium sulfate 7.5 grams, sodium chloride 2.7 grams, potassium chloride 1 gram, vitamin C 4.7 grams, and sodium ascorbate 5.9 grams per liter of solution (90413,90415,90424). In the U.S., MoviPrep is approved by the Food and Drug Administration (FDA) for bowel preparation prior to a colonoscopy.
• Cataracts. Dietary and supplemental intake of vitamin C may reduce the risk of developing cataracts. Details: Population research suggests that people with the highest total intake of vitamin C have about a 19% reduced risk of developing cataracts when compared with those with the lowest total intake, with the most benefit observed for nuclear cataracts (96711). Additionally, another observational study shows that higher supplemental intake of vitamin C over 10 years is associated with a 60% reduction in the incidence of nuclear and cortical cataracts (4208). Other population research suggests that individuals with the highest blood levels of vitamin C have a 33% lower odds of developing age-related cataract, but any benefit is limited to Asian populations (90944). An umbrella review of meta-analyses also shows that dietary intake of vitamin C is associated with a 27% lower odds of cataract development (112095). However, a prospective clinical study shows that a combination of vitamin C, vitamin E, and beta-carotene does not prevent age-related loss of vision from cataracts in well-nourished people with an average supplementation duration of 6.3 years (7304).
• Common cold. Oral high-dose vitamin C might modestly shorten and reduce cold symptoms; however, taking vitamin C prophylactically does not seem to prevent the development of a cold. Details: There is substantial controversy about the effectiveness of vitamin C for treating the common cold (1969,1989,7100,9835,9836). The majority of evidence shows that taking high doses of vitamin C orally might decrease the duration of cold symptoms by 1-1.5 days in some patients (1966,1967,1968,1987,6458,7102,9832,83487). However, other studies have found no effect with doses up to 3 grams daily (9833). A meta-analysis of clinical research in healthy children and adults shows that taking vitamin C 1-4 grams daily for one week to 5 months reduces cold severity by 13%, limits absences from daily activities, and improves the duration of severe symptoms, but does not reduce the duration of mild symptoms, when compared with placebo (113665). Vitamin C has also been investigated for preventing the common cold. A meta-analysis of clinical research suggests that vitamin C supplementation decreases the incidence of cold in individuals exposed to physical stress, but not in the general population (83487). Other research suggests vitamin C may be more effective for treating cold symptoms in children than in adults. Also, there may be a dose-dependent response; doses of at least 2 grams daily seem to work better than 1 gram doses (9834). Taking vitamin C supplements prophylactically does not decrease the risk of catching a cold (1966,1967,1968,1987,3042,6458,7101,9832). Dietary intake of vitamin C also does not seem to affect the risk of getting a cold (10780).
• Complex regional pain syndrome. Most research shows that taking oral vitamin C after a distal radius (i.e. wrist) fracture or surgery seems to reduce the risk of developing complex regional pain. However, it is unclear if oral vitamin C is beneficial in reducing the risk of complex regional pain in other orthopedic surgeries. Details: Although some research has found no benefit in patients with distal radius (i.e. wrist) fractures (90411,96702), most clinical research shows that taking vitamin C 500 mg daily, and possibly doses of up to 1500 mg daily, for 45-50 days beginning immediately after fracture can reduce the risk of developing complex regional pain syndrome (2045,16302,96700,96706). Reasons for discrepancies are unclear but might relate to differences in diagnostic criteria for complex regional pain syndrome (96702). Research in patients undergoing various orthopedic surgeries has also shown benefit with the use of vitamin C for the prevention of complex regional pain syndrome; however, some findings are conflicting. (90422,108076,115613). One meta-analysis of clinical research in patients undergoing ankle, foot, or wrist surgery shows that taking vitamin C 500-1000 mg for 42-50 days following surgery reduces the rate of complex regional pain syndrome, and may improve pain following ankle or foot surgery, when compared with placebo (108076). The validity of these findings is limited by the high heterogeneity of included trials. An additional meta-analysis of clinical research in patients undergoing a broader variety of orthopedic surgery types (i.e., ankle, foot, knee, shoulder, wrist) shows that taking vitamin C 500 to 1500 mg does not reduce the incidence of complex regional pain syndrome (115613). The reasons for these discrepant findings are unclear but may relate to the inclusion of a wide range of orthopedic surgeries.
• Exercise-induced respiratory infections. High-dose oral vitamin C seems to reduce the risk of respiratory infections associated with strenuous exercise. Details: Some preliminary clinical research suggests that prophylactic use of vitamin C in doses of 600 mg to 1 gram daily for 3-8 weeks before heavy physical exercise, such as a marathon, might prevent upper respiratory infections that sometimes follow heavy exercise (9831,83370). More recently, high doses of vitamin C have been studied. A large clinical study in army recruits undergoing basic military training shows that taking vitamin C 6 grams daily for one month reduces the odds of getting a cold by 20% when compared with placebo (102975).
• Hypercholesterolemia. Oral vitamin C seems to reduce lipid levels in patients with hypercholesterolemia. Details: A meta-analysis of clinical research in patients with hypercholesterolemia shows that taking vitamin C 500 mg daily for at least 4 weeks reduces low-density lipoprotein (LDL) cholesterol by about 8 mg/dL and reduces triglycerides by about 20 mg/dL when compared with control (83445).
• Hypertension. Oral vitamin C seems to modestly reduce blood pressure in patients with hypertension, but some evidence is conflicting. Details: Vitamin C seems to modestly reduce systolic blood pressure (SBP), without meaningful effects on diastolic blood pressure (DBP) (2044,9822,13162,83483,102974). A meta-analysis of 13 clinical trials in patients with hypertension, with or without other comorbidities, shows that taking a median dose of vitamin C 500 mg daily for 8 weeks reduces SBP but not DBP by about 5 mmHg. Some of the studies used vitamin C in combination with other supplements, such as vitamin E and magnesium. When studies assessing vitamin C alone were analyzed, the magnitude of reduction in SBP decreased (83483). A newer meta-analysis of small clinical studies in patients with essential hypertension shows that taking vitamin C 200 mg or more daily reduces SBP by about 4 mmHg and DBP by about 2 mmHg (102974). However, this newer analysis omitted numerous relevant studies and included studies with normotensive patients and those without an adequate control, limiting the validity of its findings. In contrast, a network meta-analysis of small, low-quality clinical studies comparing five different vitamins in adults with essential hypertension shows that vitamin C does not reduce SBP, DBP, mean 24-hour SBP, mean 24-hour DBP, or heart rate when compared with placebo and when indirectly compared with vitamin B2, vitamin D, vitamin E, and folic acid. However, the included studies were of low quality and high heterogeneity, particularly in dosing, limiting the validity of the results (113668).
• Laser skin resurfacing. Topical vitamin C seems to reduce erythema occurring after cosmetic laser skin resurfacing procedures intended to reduce scars and wrinkles. Details: There is some evidence that an aqueous formulation of topical vitamin C can decrease the degree and duration of erythema following cutaneous carbon dioxide laser resurfacing for scar and wrinkle removal (1959).
• Lead toxicity. Dietary vitamin C seems to lower concentrations of lead in the blood. Details: Observational research has found that consuming more vitamin C from dietary sources is associated with lower blood concentrations of lead. People who consumed at least 340 mg of vitamin C daily as part of the diet had lower blood lead levels than those who consumed less than 100 mg vitamin C daily (3097,3098,3099).
• Nitrate tolerance. Oral vitamin C might prevent nitrate tolerance in some patients. Details: Small clinical studies show that taking vitamin C orally seems to prevent the development of nitrate tolerance in patients taking sublingual nitroglycerin. There is some evidence that short-term vitamin C supplementation can prevent tolerance to the vasodilatory effects of nitrates (1441,1961).
• Postoperative pain. Oral or intravenous vitamin C might prevent acute postoperative pain following certain surgeries. It is unclear if vitamin C reduces chronic postoperative pain. Details: A meta-analysis of 7 small clinical studies in adults undergoing elective surgery shows that receiving perioperative vitamin C, either as 1 gram orally, 2-3 grams intravenously, or 50 mg/kg intravenously, modestly reduces acute pain and opioid requirements for up to 24 hours when compared with control (105457). Most surgeries were laparoscopic and included cholecystectomy, colectomy, hysterectomy; two non-laparoscopic surgeries included uvulopalatopharyngoplasty with tonsillectomy and major abdominal surgery (90418,99840,105457). A meta-analysis of clinical trials in adults undergoing noncardiac surgery (i.e., orthopedic, abdominal, gynecologic, kidney transplantation) shows that administering perioperative vitamin C, either orally or intravenously, reduces postoperative intravenous morphine requirements at 2, 24, and 48 hours after surgery and improves pain scores at 2, 6, and 24 hours after surgery when compared with placebo. The dose of vitamin C did not appear to impact outcomes. However, when only laparoscopic surgeries are included, perioperative vitamin C does not improve pain or morphine use when compared with placebo (108087). Use of vitamin C perioperatively has also been evaluated in other surgery types with generally similar outcomes. A moderate-sized clinical study in adults undergoing total hip arthroplasty shows that intravenous vitamin C 3 grams perioperatively reduces 24-hour post-operative morphine use and subjective pain scores when compared with placebo; however, these improvements do not appear to be clinically significant (115500). The validity of these results is limited by a short follow-up period. Additionally, a small observational study in adults undergoing surgery for wisdom tooth extraction shows that taking vitamin C 500 mg three times daily for 7 days in addition to standard treatment reduces pain 24, 48, and 72 hours after surgery when compared with control (113664). However, a moderate-sized clinical study in adults undergoing transurethral resection of a bladder tumor under general anesthesia shows that administering intravenous vitamin C 1 gram after induction of anesthesia reduces the incidence and severity of catheter-related bladder discomfort immediately after surgery and at 1 and 2 hours postoperatively, but not 6 hours, when compared with placebo. Further, vitamin C does not reduce postoperative pain scores or analgesic requirements when compared with placebo (111645). Vitamin C has also been evaluated for reducing chronic pain after surgery. Clinical research in patients undergoing surgery for foot or ankle trauma shows that taking vitamin C 500 mg orally twice daily postoperatively for 6 weeks reduces pain scores when compared with placebo at 2 weeks and 6 weeks. The mean total amount of diclofenac used for pain relief over the 6-week period is also reduced, from 5.7 grams with placebo to 3.4 grams with vitamin C (102131).
• Wrinkled skin. Topical vitamin C might reduce the appearance of existing wrinkles. Details: Topical preparations containing vitamin C seem to improve the appearance of wrinkled skin. Some evidence shows that vitamin C 3% applied for 12 weeks might reduce facial wrinkles (14008). A small clinical study shows that applying a dissolving microneedle patch containing vitamin C 5.6% every 4 days for 12 weeks to crow's feet on one side of the face reduces wrinkles when compared to control treatment applied on the other side of the face (98780). Other clinical research in females aged 30-60 years shows that applying an oil-soluble cream containing the vitamin C derivative tetra-isopalmitoyl ascorbic acid 1%, 2%, or 3% to the periorbital area twice daily for 8 weeks reduces visual wrinkle grading when compared with placebo. A dose analysis shows greater improvements in wrinkle parameters, average wrinkle depth, and mean depth with the lower concentration, while greater improvements in maximum roughness and maximum depth are observed with the higher concentration (108072). This study only included individuals defined as having Fitzpatrick skin type III or IV; it effects on other skin types is unclear. Preparations containing vitamin C in combination with other ingredients have also been investigated. A small low-quality trial in females with moderately photodamaged and hyperpigmented facial skin shows that applying a moisturizer with vitamin C 30%, vitamin E, and coenzyme Q10 once daily in the morning, along with applying retinol 0.5% once daily or once every other day for 12 weeks, seems to improve skin tone, photodamage, and wrinkles when compared to baseline (99085). In another small trial, a topical preparation containing vitamin C 10% as L-ascorbic acid along with acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied to photo-aged facial skin for 3 months improves fine and coarse wrinkling, yellowing and sallowness, roughness, and skin tone when compared with placebo (6155). It is unclear if the beneficial effects of these products are due to vitamin C, other ingredients, or the combination.

POSSIBLY INEFFECTIVE

• Acute bronchitis. Oral vitamin C doesn't seem to improve symptoms of acute bronchitis. Details: A clinical study in adults with acute bronchitis shows that taking vitamin C orally 500 mg on day 1, then 250 mg on days 2 through 5 (similar to an azithromycin regimen) doesn't seem to have any effect on quality of life or bronchitis duration when compared with azithromycin (9827).
• Asthma. Oral vitamin C doesn't seem to prevent asthma or improve lung function. Details: Although some observational research has found that some patients with asthma might have lower serum vitamin C levels (5873), other observational research found that increased dietary vitamin C intake is not associated with a reduced risk of asthma or improved lung function (15006,34567). In addition, clinical research shows that supplemental intake of vitamin C does not reduce asthma symptoms, improve lung function, or reduce the use of inhaled steroids in asthma patients (90409).
• Atherosclerosis. Oral vitamin C does not seem to reduce the progression of atherosclerosis. Details: A clinical study shows that taking a specific combination product containing slow-release vitamin C 250 mg and vitamin E 136 IU (CellaVie, Ferrosan A/S) twice daily modestly slows the 3-year progression of atherosclerosis of the carotid artery in males, but not females. This result persisted at a 6-year follow-up of this study (1918,10473). However, when this form of vitamin C is used alone, it does not slow the 3-year progression of atherosclerosis of the carotid artery (1918).
• Bladder cancer. Oral vitamin C does not reduce the risk of bladder cancer or mortality from bladder cancer. Details: Epidemiological research has found that supplemental vitamin C intake is not associated with mortality rate in patients with bladder cancer (9839). A secondary analysis of a large clinical trial, the Physicians' Health Study II, in healthy men aged at least 50 years also shows that taking vitamin C 500 mg daily alone or with vitamin E 400 IU daily for up to 10 years does not reduce the risk of developing bladder cancer or bladder cancer-related deaths when compared with placebo (90097).
• Cardiovascular disease (CVD). Oral vitamin C does not seem to be beneficial for either primary or secondary CVD prevention. Details: Vitamin C does not seem to be beneficial for primary prevention of CVD. Some population research has found that higher supplemental vitamin C or dietary vitamin C has been associated with a reduced risk of developing CVD (10358,14108,109779), while other observational research has found no benefit (34566,10358,14108). However, meta-analyses of clinical research in healthy patients show that vitamin C supplementation does not prevent CVD or coronary heart disease when compared with control (97308,104025). In 2004, the American Heart Association stated that current evidence does not justify use of antioxidants such as vitamin C for reducing the risk of CVD (12142). Evidence is also negative for secondary prevention in people with coronary heart disease. Population studies have found that higher serum vitamin C was associated with no effect or decreased CVD mortality from CVD (3910,5878). A meta-analysis of two large clinical trials shows that vitamin C supplementation does not reduce CVD events or CVD mortality when compared with control (97308).
• Colorectal cancer. Oral vitamin C does not seem to prevent colorectal cancer. Details: Population research has found that dietary vitamin C intake is not associated with a reduced risk of developing colon cancer. When total vitamin C intake from food and supplements is considered, there is a modest association (34600). However, most clinical trials show that supplemental vitamin C, alone or along with other antioxidants, does not reduce the risk of colorectal cancer development, colorectal cancer or adenoma recurrence, or colorectal cancer-related mortality (34580,34581,34594,90097,90089,92903).
• Fetal and premature infant mortality. Oral vitamin C does not seem to prevent neonatal death. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of neonatal death (83472,96707).
• Fractures. Oral vitamin C does not seem to improve fracture healing. Details: Clinical research shows that taking vitamin C 500 mg daily for 50 days following an acute distal radial fracture does not improve physical function, symptoms, or healing rates when compared with placebo (90411).
• Helicobacter pylori. Oral vitamin C does not seem to improve eradication of H. pylori. Details: Most clinical research shows that treatment with vitamin C, alone or in combination with vitamin E, does not improve the eradication rate of H. pylori when taken with a standard eradication regimen when compared with the eradication regimen alone (83476,90094).
• Hereditary motor and sensory neuropathy. Oral vitamin C does not seem to improve neuropathy in these patients. Details: In a meta-analysis of five studies in patients with Charcot-Marie-Tooth disease type 1A, taking vitamin C 1-4 grams orally daily for 1 year did not improve neuropathy when compared with placebo (99084). Continuing vitamin C 4 grams daily for 2 years also does not improve neuropathy in these patients (90419).
• Interferon-related retinopathy. Oral vitamin C does not seem to improve retinopathy associated with interferon therapy. Details: A small clinical study in patients with chronic hepatitis C receiving interferon therapy shows that taking vitamin C 600 daily orally does not seem to reduce the risk of retinopathy from interferon therapy when compared with control (10355).
• Leukemia. Oral vitamin C does not seem to reduce the risk of leukemia or mortality from leukemia. Details: A large clinical trial in men aged at least 50 years shows that taking vitamin C 500 mg daily, alone or along with vitamin E 400 IU daily, for up to 10 years does not reduce the risk of developing leukemia or leukemia-related deaths when compared with placebo (90097).
• Low birth weight. Oral vitamin C does not seem to reduce the risk of infants being born with a low birth weight. Details: Meta-analyses of clinical research show that maternal use of oral vitamin C alone or with other supplements does not reduce the risk of giving birth to infants with low birth weight when compared with control (83450,83472).
• Lung cancer. Oral vitamin C does not seem to reduce the risk of lung cancer. Details: Two meta-analyses of clinical research suggest that taking vitamin C, alone or in combination with vitamin E, does not reduce the incidence of lung cancer or lung cancer-related mortality (34528,34632). Also, a clinical study in females shows that taking supplemental vitamin C 500 mg daily, with or without vitamin E and beta carotene, is associated with an INCREASED risk of lung cancer when compared with placebo (34580). However, another large epidemiological cancer screening trial with a mean follow-up of over 12 years suggests that moderate dietary intake of vitamin C around 500 mg daily is protective against lung cancer, but higher doses of vitamin C might increase the risk of lung cancer (112096).
• Melanoma. Oral vitamin C does not seem to reduce the risk of melanoma. Details: Clinical research shows that taking vitamin C 500 mg daily, alone or along with vitamin E 400 IU daily, for up to 10 years does not reduce the risk of developing melanoma or melanoma-related deaths when compared with placebo in men aged at least 50 years (90097).
• Miscarriage. Oral vitamin C does not seem to reduce the risk of miscarriage. Details: A meta-analysis of clinical research shows that taking vitamin C alone or with other supplements does not reduce the risk of miscarriage when compared with control (94820).
• Overall mortality. Oral vitamin C does not reduce overall mortality. Details: Although population research suggests that higher dietary intake and higher plasma vitamin C levels are associated with a reduced risk of mortality from all causes (3910,109779), vitamin C supplementation does not seem to affect overall mortality. Meta-analyses of clinical research show that taking vitamin C supplements does not reduce overall mortality when compared with control (34622,111641). Clinical studies of vitamin C used in combination with vitamin E, beta carotene, and/or selenium and zinc, also show no benefit for overall mortality (9817,14109).
• Pancreatic cancer. Oral vitamin C does not seem to prevent pancreatic cancer. However, it is unclear if intravenous vitamin C is beneficial for treatment of pancreatic cancer. Details: Observational research has found that increased dietary vitamin C intake is associated with up to a 30% reduced risk of pancreatic cancer (99083,99086). However, clinical research shows that supplemental vitamin C 500 mg daily does not reduce the risk of pancreatic cancer in females (34580). Also, taking vitamin C in combination with beta-carotene plus vitamin E does not reduce the risk of pancreatic cancer (12185,34581). While research suggests oral vitamin C may not prevent pancreatic cancer, intravenous vitamin C is being explored in the treatment of pancreatic cancer. A small, open-label clinical study in adults with stage IV pancreatic ductal adenocarcinoma shows that administration of intravenous vitamin C 75 grams three times weekly throughout each cycle of chemotherapy increases median overall survival and progression free survival by approximately 8 months and 2 months, respectively, when compared with chemotherapy alone (115499). The validity of these results is limited by potential overestimation of treatment effects, influenced by small sample size, differences in chemotherapy doses, and early study termination.
• Pre-eclampsia. Oral vitamin C does not seem to prevent pre-eclampsia. Details: Despite some early positive research in high-risk pregnancies, the majority of meta-analyses and clinical studies show that taking vitamin C alone or with vitamin E or other supplements does not reduce the risk of pre-eclampsia when compared with control. There is even some concern that vitamin C supplementation may increase the risk of gestational hypertension (3236,83450,83472,83474,96707).
• Preterm labor. Oral vitamin C does not seem to prevent preterm labor. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of preterm labor when compared with control (83450,83472,96707).
• Prostate cancer. Oral vitamin C does not seem to prevent prostate cancer. However, it is unclear if intravenous vitamin C is beneficial for the treatment of prostate cancer. Details: A large-scale clinical study (The SU.VI.MAX study) shows that a combination of vitamin C 120 mg, vitamin E (alpha-tocopherol) 30 mg, beta-carotene 6 mg, selenium 100 mcg, and zinc 20 mg, taken daily for an average of 8 years, does not reduce the risk of prostate cancer overall. However, it might reduce the risk of prostate cancer in those who have normal PSA levels. It does not seem to be beneficial for reducing the risk of prostate cancer in patients with PSA levels above 3 mcg/L (14135). Another large scale study (Physician's Health Study II) shows that taking vitamin C 500 mg daily for an average of 8 years does not significantly reduce the risk of prostate cancer when compared with placebo (16708). Similarly, results from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial seem to show that supplemental or dietary intake of vitamin C does not reduce the risk of prostate cancer when compared to individuals not taking vitamin C (14124). While research suggests oral vitamin C may not prevent prostate cancer, intravenous vitamin C is being explored in the treatment of prostate cancer. A small clinical study in adults with metastatic castration-resistant prostate cancer shows that administration of intravenous vitamin C 1 gram/kg twice weekly in combination with docetaxel for up to 24 weeks does not reduce prostate-specific antigen (PSA) by 50% or more when compared with docetaxel alone (115611). This study may have been underpowered to show a difference between groups.
• Radiation dermatitis. Topical vitamin C does not seem to prevent radiation dermatitis in cancer patients. Details: A small clinical study shows that applying a 10% vitamin C solution does not appear to protect from radiation dermatitis when applied to the scalps of patients treated with radiation for intracranial tumors (789).
• Small for gestational age (SGA). Oral vitamin C does not seem to reduce SGA. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of small for gestational age birth when compared with control (83450,83472).
• Stillbirth. Oral vitamin C does not seem to prevent stillbirth. Details: Meta-analyses of clinical research show that maternal use of vitamin C alone or with other supplements does not reduce the risk of stillbirth when compared with control (83472,96707).

LIKELY INEFFECTIVE

• Coronavirus disease 2019 (COVID-19). Oral vitamin C, even at high doses, does not seem to speed recovery from COVID-19 in non-hospitalized patients. Most studies show that oral or intravenous vitamin C given to patients hospitalized with COVID-19 does not improve organ function or survival, but the evidence is conflicting. It is unclear whether vitamin C is beneficial for long COVID. Details: A clinical study in adult outpatients with confirmed COVID-19 shows that taking oral vitamin C (ascorbic acid) 8000 mg in 2-3 divided doses daily, alone or with zinc gluconate 50 mg daily, for 10 days does not reduce symptom severity when compared with standard care (104450). The study was terminated prior to complete enrollment due to futility and apparent lack of effect from vitamin C and/or zinc supplementation. Limitations of this study include a lack of placebo control and blinding. Additionally, this study has been criticized for methodologic concerns (106624). Another small clinical trial in adult outpatients with confirmed COVID-19 shows that taking vitamin C 1000 mg daily for 14 days does not improve symptoms or quality of life when compared with placebo (109462). Vitamin C has also been evaluated in patients hospitalized with COVID-19. A very large analysis of two multinational clinical studies in critical and non-critical adults hospitalized with COVID-19 shows that administering intravenous vitamin C 50 mg/kg every 6 hours for 96 hours does not improve organ support-free days or survival and has a high probability of futility and worsened outcomes when compared with placebo (113666). Individual prospective and retrospective studies in critically ill patients hospitalized with COVID-19 in various countries have found that administering vitamin C, either enterally as 500-1000 mg daily or intravenously as 8-24 grams daily or 50 mg/kg daily, does not significantly reduce in-hospital or short-term mortality, hospital length of stay, or end-organ failure when compared with control groups receiving standard care alone. Additionally, all but one study found no change in the need for mechanical ventilation (105458,105465,106937,106938,108075,108079,108081). However, a meta-analysis and some small individual studies have found that vitamin C is modestly beneficial for patients hospitalized with COVID-19. A meta-analysis of 10 clinical trials and 9 observational studies in patients hospitalized with COVID-19 shows that receiving oral or intravenous vitamin C daily reduces the odds of in-hospital mortality by 41% when compared with control. When only clinical trials were considered, the odds of in-hospital mortality were decreased by 56%; however, this reduction was only identified in studies using vitamin C 10 grams daily or less. Conversely, supplementation with vitamin C increased the length of intensive care unit (ICU) stay by nearly 2 days and did not impact length of hospital stay or reduce the need for mechanical ventilation, liver injury, or cardiac injury (109955). Similarly, a meta-analysis of 8 clinical studies in primarily hospitalized patients with moderate to severe COVID-19 shows that vitamin C administered orally or intravenously decreases the risk of all-cause mortality by 16% when compared with control (114488). Additionally, a small study found a small improvement in survival when compared with standard care; however, the overall survival rate in this study was low (108075). Another clinical study in patients hospitalized in Turkey with COVID-19 shows that adding high-dose intravenous sodium ascorbate 50 mg/kg to a treatment regimen of hydroxychloroquine, azithromycin, and zinc may improve recovery time, with 57% and 39% of patients achieving total recovery at day 15 in the vitamin C and control groups, respectively (108071). However, the validity of this trial is limited due to unclear reporting. Vitamin C has also been evaluated in combination with other ingredients in patients with long COVID. Preliminary clinical research in adults with long COVID and persistent fatigue shows that taking a specific combination product containing vitamin C 500 mg and L-arginine 1.66 grams (Bioarginina C, Farmacetici Damor) for 28 days increases 6-minute walk test distance by 10% and reduces self-reported fatigue when compared with placebo (110390). However, it is unclear whether these effects are due to vitamin C, L-arginine, or the combination.
• Sepsis. Intravenous vitamin C, alone or in combination with thiamine and/or hydrocortisone, does not prevent organ failure, reduce intensive care or hospital length of stay, or reduce mortality in sepsis or septic shock. Details: Observational research suggests that patients with septic shock are more likely to have low plasma levels of vitamin C (100317). However, three randomized clinical trials in patients with sepsis or septic shock show no benefit with intravenous vitamin C, with or without thiamine, for improving organ function and preventing organ failure when compared with control treatment (102130,104027,114489). A small clinical study in patients with septic shock shows that intravenous vitamin C 50 or 150 mg/kg daily for 4 days does not improve organ dysfunction or failure rates, duration of hospital or intensive care unit (ICU) length of stay, duration of mechanical ventilation, or mortality rate when compared with placebo (114489). Another clinical study in patients with septic shock shows that administering an intravenous bolus of vitamin C 1000 mg followed by a continuous infusion of 250 mg/hour for 96 hours, starting within 24 hours of vasopressor initiation, does not improve 28-day or ICU mortality when compared with placebo. A subgroup analysis shows that the addition of corticosteroids does not affect outcomes in either group (108078). This study may have been inadequately powered to detect a difference between groups. Also, a larger clinical trial in adults with sepsis receiving vasopressor therapy in the ICU shows that intravenous administration of vitamin C 50 mg/kg every 6 hours for up to 4 days increases the risk of death or persistent organ dysfunction at day 28 by 14% to 21% when compared with placebo. There were no differences in mortality at 6 months (109459,111643). Vitamin C has also been frequently studied in patients with sepsis and septic shock in a specific combination regimen (HAT therapy) which includes intravenous vitamin C 1.5-2 grams with hydrocortisone 50 mg every 6 hours and thiamine 200 mg every 12 hours. While some retrospective research has found HAT therapy to be beneficial in sepsis (100315,102980), high quality, prospective clinical research has not confirmed these findings (105447,106620,109956). Several meta-analyses of randomized controlled trials and small clinical studies in patients with sepsis or septic shock show that intravenous vitamin C, either alone, as a component of HAT therapy, or in combination with thiamine, does not reduce short- or long-term mortality, ICU or hospital length of stay, kidney injury, or duration of mechanical ventilation, but modestly improves duration of vasopressor use and procalcitonin clearance, when compared with placebo or standard care. These analyses also show mixed results with respect to improvement in sequential organ failure assessment (SOFA) scores within 72 hours (105447,106620,106935,108073,109460,111298,111300,111301,111642,112479). Most studies included in the analyses administered HAT therapy for 2-10 days and compared it with normal saline control or with hydrocortisone alone (102129,102998,104027,104028,104032,105446). Although some subgroup analyses suggests that intravenous vitamin C alone in patients with sepsis may improve short-term mortality (106620,111298), other meta-analyses have not shown this benefit in subgroup analyses (111300). In addition, meta-analyses have identified significant publication bias (111298,111300). Long-term follow up from a study in patients with sepsis-induced respiratory and/or cardiovascular dysfunction shows that receiving HAT therapy does not improve cognitive, psychological, or functional status after 6 months and, for some domains, HAT therapy was worse when compared with placebo (111299). Studies evaluating intravenous vitamin C, either alone, as a component of HAT therapy, or in combination with thiamine, in mixed critically ill populations have also shown mixed findings. Four meta-analyses of randomized controlled trials and observational studies show that intravenous vitamin C does not have a significant effect on the length of hospital stay, mortality at 1 month, ICU mortality, use of invasive ventilation, use of renal replacement therapy, organ function, or incidence of kidney injury when compared with placebo or standard care. The meta-analyses reach conflicting conclusions on whether intravenous vitamin C reduces the risk of in-hospital mortality, 30-day mortality, and the duration of ICU stay. When only data from low risk-of-bias clinical trials are considered, the effects of intravenous vitamin C on mortality at any point are no longer significant (106933,106934,109957,113663). However, a subgroup analysis in one of these analyses suggests that intravenous vitamin C as monotherapy, or in doses of at least 10 grams daily, may improve overall mortality (106934). Vitamin C also does not appear to benefit complications from sepsis, such as vasoplegic shock. A small clinical study in adults in the ICU with vasoplegic shock mostly secondary to sepsis and requiring moderate vasopressor support shows that administering intravenous vitamin C as sodium ascorbate 1.5 grams every 6 hours for 5 days or until cessation of vasoactive therapy does not reduce the duration of vasopressors, vasopressor dose, hospital or ICU length of stay, or mortality outcomes when compared with placebo (112475).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Atrophic acne scars. It is unclear if applying topical vitamin C after microblading improves atrophic acne scars. Details: A clinical study in adults with mild to severe atrophic acne scarring shows that applying a serum containing vitamin C 17% to the face after a once-monthly home microblade treatment for 4 months improves the appearance of acne scars at month 5 when compared with baseline (108086). Although this study enrolled a control group that used topical insulin in place of vitamin C, no between-group statistical comparisons were conducted, limiting the validity of this study.
• Age-related macular degeneration (AMD). It is unclear if dietary vitamin C or oral vitamin C taken in combination with other ingredients prevents AMD. Details: An umbrella review of meta-analyses shows that increased dietary intake of vitamin C is associated with 21% higher odds of developing AMD (112095). A population study suggests that vitamin C intake is associated with increased odds of developing age-related maculopathy (9823). However, other population studies have found no association between dietary or supplemental vitamin C intake and the risk of developing AMD (14007,14257). When taken in combination with other ingredients, most clinical and population research shows that taking vitamin C 500 mg along with other antioxidants such as vitamin E 400 IU, beta-carotene 15 mg, and/or elemental zinc 80 mg reduces the risk of visual acuity loss by 23% to 27%, progression to advanced AMD at 5 years by 25% to 32%, and AMD overall (7303,7304,11326,14257,90069). The antioxidant plus zinc combination seems to reduce the risk of progression to advanced AMD in these patients more than taking the antioxidants without zinc (7303,90069). More evidence is needed to determine what role, if any, vitamin C intake has on the risk of developing AMD.
• Aging skin. Topical vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in females aged 30-65 years shows that applying a specific liquid (Antioxidant and Collagen Booster Serum, Max Biocare Pty Ltd.) containing vitamin C 20%, red raspberry leaf cell culture extract 0.0005%, and vitamin E 1% to the face nightly for 8 weeks, in addition to regular facial skin products, improves skin color, elasticity, radiance, smoothness, and appearance of wrinkles when compared with regular facial skin products alone (102355).
• Albuminuria. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that taking vitamin C 1250 mg plus vitamin E 680 IU daily for 4 weeks can reduce the excretion of albumin by about 19% when compared with placebo in patients with type 2 diabetes (10434).
• Allergic rhinitis (hay fever). It is unclear if oral vitamin C is beneficial in patients with hay fever. Details: Epidemiological research has found that higher vitamin C plasma levels are not associated with a decreased risk of allergic rhinitis (15200). However, clinical research shows that some forms of vitamin C might help. In one small clinical study, intranasal vitamin C administered three times daily for 2 weeks reduces nasal secretions, nasal blockage, and edema in up to 74% of patients with perennial allergic rhinitis (15201). Another small clinical study in patients with seasonal allergic rhinitis shows that taking a single oral dose of vitamin C 2 grams reduces bronchial responsiveness to histamine at one hour after ingestion (15202). However, in another small study in patients with seasonal allergic rhinitis taking vitamin C orally in doses up to 4 grams daily for 3 days does not appear to suppress cutaneous or nasal response to histamine when compared to placebo (15203).
• Alzheimer disease. It is unclear if dietary vitamin C helps to prevent this condition. Details: Most epidemiological research has found that dietary intake of vitamin C is associated with a 17% reduced risk of developing Alzheimer disease (4636,9824,10131,13165,90082).
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). It is unclear if oral vitamin C helps to prevent ALS. Details: Observational research has found that increased dietary or supplemental intake of vitamin C is not associated with risk of developing ALS (90412).
• Anthracycline cardiotoxicity. Although there is interest in using oral vitamin C for anthracycline-induced cardiac toxicity, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
• Aspirin-associated gastric damage. It is unclear if oral vitamin C helps to prevent gastric damage caused by aspirin. Details: Some clinical research shows that vitamin C 480 mg might prevent gastric damage associated with taking aspirin 400 mg by decreasing blood loss and preventing decreased gastric blood flow (10357). However, a small clinical study in healthy patients shows that taking vitamin C 500 mg as ascorbic acid with aspirin 600 mg actually increases gastrointestinal permeability to a greater extent than either ingredient taken alone (98781).
• Athletic performance. It is unclear if oral vitamin C improves athletic performance. Details: Although some small preliminary clinical studies suggest that vitamin C might improve certain biomarkers during exercise (82922), a meta-analysis of small clinical trials in older and younger adults shows that taking vitamin C 500-1000 mg daily, with or without vitamin E, does not improve endurance, lean mass, or muscle strength when compared with placebo (102973). A more recent, small clinical study in recreationally trained males shows that taking vitamin C 1000 mg and vitamin E (as alpha-tocopherol) 235 mg daily for 10 weeks while participating in a resistance training program does not improve measures of muscle strength when compared with placebo (109959).
• Atopic disease. It is unclear if dietary vitamin C helps to prevent atopic disease. Details: Population research has found that higher intake of vitamin C is not associated with a reduced risk of eczema, wheeze, IgE-mediated food allergy, or allergic sensitization (90098).
• Attention deficit-hyperactivity disorder (ADHD). Small clinical studies suggest that high-dose oral vitamin C may not improve symptoms in patients with ADHD. Details: Some research suggests that taking megadose vitamins, including vitamin C, does not improve ADHD symptoms (9957,9958,9959). However, other preliminary clinical research shows that taking 25 mg of vitamin C in combination with flaxseed oil providing alpha-linolenic acid 200 mg twice daily might improve measures of attention, impulsivity, restlessness, and self-control in children with ADHD when compared with baseline (14443). It is not clear if these effects are due to vitamin C, flaxseed oil, or the combination.
• Autism spectrum disorder. It is unclear if oral vitamin C is beneficial in patients with autism spectrum disorder. Details: One small clinical study shows that taking vitamin C 8 grams per 70 kg daily for 10 weeks modestly reduces autism symptom severity in school children when compared with placebo (83604).
• Bleeding. It is unclear if intravenous vitamin C can reduce bleeding after total abdominal hysterectomy. Details: A small clinical study in patients undergoing total abdominal hysterectomy shows that administration of intravenous vitamin C 1 gram the night before surgery and 1 gram during surgery reduces postoperative hemorrhage volume by around 40 mL when compared with placebo (109465).
• Brain tumor. It is unclear if oral vitamin C helps to prevent brain tumors. Details: Population research has found that vitamin C intake is associated with a 14% reduced risk of glioma. This risk reduction was more prevalent in America compared to other geographic locations (98782).
• Breast cancer. It is unclear if oral vitamin C helps to prevent breast cancer, its recurrence, or breast cancer-related mortality. Details: Some epidemiological research has found that dietary vitamin C is associated with a reduced risk of breast cancer (1444,10823,10824). However, other epidemiological research has found no association with dietary or supplemental vitamin C (10825,10826,108080). One cohort study found no association between breast cancer risk and total, dietary, or supplemental vitamin C, regardless of dose, treatment duration, or formulation (single ingredient or combination product). Additionally, hormone and menopausal status did not appear to impact risk. Vitamin C intake might be associated with a reduced risk in individuals with a family history of breast cancer in first-degree relatives (108080). In patients with breast cancer, supplemental or dietary intake of vitamin C might be associated with a reduced risk of mortality. A meta-analysis of results from population research shows that vitamin C supplementation following breast cancer diagnosis is associated with a 15% lower risk of breast cancer-related mortality when compared with no supplementation (90416). A large, observational study in patients with breast cancer undergoing radiation therapy has found that vitamin C supplementation does not reduce the risk of breast cancer recurrence over a period of 5 years when compared with no supplementation. Although the vitamin C group had notably less aggressive tumor types, recurrence-free survival was similar in both vitamin C and control groups (108082). The validity of these findings is limited due to unknown doses of vitamin C and the inclusion of various breast cancer subtypes.
• Burns. Small studies suggest that intravenous vitamin C may modestly improve symptoms in patients with severe burns. Details: A small clinical study in patients with severe burns shows that administering vitamin C intravenously (IV) 66 mg/kg hourly over 24 hours, as part of fluid resuscitation using lactated ringer solution, reduces wound edema and the volume of fluid needed when compared with fluid resuscitation alone (83145). A retrospective review of adults hospitalized with severe burns has found that those who receive a continuous IV infusion of at least 10 grams of vitamin C within 2 days of admission have an in-hospital mortality rate of 46%, compared with 58% for those who do not receive vitamin C (102128).
• Cancer. It is unclear if oral or intravenous vitamin C helps to prevent cancer or cancer-related mortality. Details: Some population research has found that DIETARY intake of vitamin C is linked with a lower risk of cancer and cancer-related mortality (3910,5878,10819,109779). However, clinical research shows that taking vitamin C SUPPLEMENTS does not reduce the risk for cancer (10819,14109,34580,90097). In people with cancer, although some clinical research has shown that taking high-dose vitamin C supplements can improve survival rates (9809,96704), other clinical research has not shown this benefit (4842,4843). In 2003, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that some scientific evidence suggests that antioxidant vitamins, such as vitamin C, may reduce the risk of certain forms of cancer. However, the FDA has determined that there is little scientific evidence supporting this claim (102334). Preliminary clinical research has also evaluated vitamin C supplements in patients with cancer. High-dose oral vitamin C, 10 grams daily, in patients with advanced cancer does not seem to improve survival or decrease disease progression (4842,4843,106617). However, preliminary clinical research suggests high doses of vitamin C, given intravenously, might have a beneficial effect on some outcomes, including survival rate in some patients with cancer (9809,96704,106617). However, there is no benefit to other patients studied in the case reports and this has not been tested in well-designed clinical trials (9809,96704).
• Cardiac arrest. It is unclear if intravenous vitamin C is beneficial for patients after cardiac arrest. Details: A small clinical study conducted in Slovenia in adult survivors of out-of-hospital cardiac arrest shows that administering intravenous vitamin C 1.5 grams every 12 hours for 8 consecutive doses, with the first dose administered within 6 hours of resuscitation, in addition to standard care protects against arrhythmias and reduces the length of intensive care unit (ICU) stay when compared with placebo and standard care. However, intravenous vitamin C does not appear to protect against neurological or myocardial injury, reduce the need for mechanical ventilation, reduce the duration of hospital stay, or increase survival when compared with placebo (113667).
• Carpal tunnel syndrome. Vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in adults with mild to moderate carpal tunnel syndrome shows that taking a combination product containing vitamins C, E, B1, B2, B6, and B12, alpha-lipoic acid, acetyl-L-carnitine, phosphatidylserine, and turmeric twice daily for 60 days reduces symptom severity and pain but does not improve measures of hand and wrist function when compared with control (111702). The validity of these effects is limited by a lack of blinding. The study may also be inadequately powered to detect a difference between groups. Additionally, it is unclear if the effects are due to vitamin C, other ingredients, or the combination.
• Cervical cancer. It is unclear if oral vitamin C helps to prevent cervical cancer. Details: Observational research has found that higher vitamin C intake is associated with a 33% to 42% reduced odds of cervical neoplasm. Increasing vitamin C intake by 50 mg daily is associated with an 8% reduced odds of cervical neoplasm (34609,98771).
• Child growth. Some clinical research in pregnant smokers suggests that taking vitamin C during pregnancy may improve pulmonary function in the offspring from birth to 6 years of age. Details: A meta-analysis of 4 data sets from one large clinical study in pregnant adults who smoke at least one cigarette daily shows that taking supplemental vitamin C 500 mg daily during pregnancy reduces lower airway resistance and improves lung capacity of the offspring at 0, 3, 12, and 60 months of age, but does not improve airway obstruction, when compared with control (113670). Additionally, one of the clinical studies included the meta-analysis shows that taking vitamin C during pregnancy lowers the occurrence of wheezing in offspring at 4-6 years of age (114496,114497).
• Chronic fatigue syndrome (CFS). Although there is interest in using oral vitamin C for CFS, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
• Colistin-induced nephrotoxicity. It is unclear if intravenous vitamin C helps to prevent nephrotoxicity from colistin. Details: A small clinical study shows that intravenous administration of vitamin C 2 grams every 12 hours along with colistin for around 9-10 days does not prevent nephrotoxicity when compared with colistin therapy alone (99839). However, this study was limited by a lack of statistical power to detect differences between the study groups.
• Contrast induced nephropathy. It is unclear if oral vitamin C helps to prevent contrast-induced nephropathy (CIN). Details: Some clinical research shows that taking vitamin C before and after coronary angiography reduces the risk of developing CIN by 33% to 55% when compared with placebo in patients with renal dysfunction (12234,90421). However, other clinical evidence published since 2012 suggests that vitamin C given orally and/or intravenously before and after angiography does not reduce the risk of CIN compared with control in high-risk patients with chronic renal insufficiency or diabetes (91232,91236,90410,90425). Reasons for the discrepancies are not entirely clear. However, it is possible that the lack of significant benefit from vitamin C in the latter studies results from the fact that incidences of CIN have become less common than in the past due to avoidance of dehydration, use of smaller catheters, and use of contrast agents with reduced nephrotoxicity (90429).
• Coronary artery bypass graft (CABG) surgery. It is unclear if intravenous vitamin C helps to improve patient outcomes after CABG surgery. Details: A small clinical study shows that giving vitamin C 5 grams intravenously (IV) before anesthesia induction and 5 grams in the cardioplegia solution used during surgery shortens the length of stay in the intensive care unit (ICU) by about 8 hours (102127). However, some limited research suggests that IV vitamin C does not resolve cardiac surgery complications. A small clinical study in patients with vasoplegia after receiving CABG and other cardiac surgeries shows that receiving IV vitamin C 1.5 grams every 6 hours after being admitted to the ICU does not improve vasoplegia when compared with control (102981).
• Delirium. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Observational research in adults with septic shock has found that receiving intravenous thiamine 400 mg daily with vitamin C 6 grams daily, both in divided doses, is not associated with reduced delirium when compared with control (103001).
• Dental plaque. It is unclear if vitamin C in a chewing gum helps to reduce dental plaque formation. Details: A small clinical study in patients with calculus shows that chewing 10 pieces of gum, each containing 60 mg of vitamin C, daily for 3 months reduces the formation of dental calculus, visible plaque, and the number of bleeding sites when compared not chewing gum (83303). The validity of this finding is limited by a lack of placebo group.
• Depression. It is unclear if oral vitamin C is beneficial for the treatment or prevention of depression. Details: A small clinical study in children and adolescents shows that taking vitamin C 500 mg orally twice daily in combination with fluoxetine 10-20 mg daily for 6 months reduces most symptoms of major depressive disorder when compared with taking fluoxetine alone (90404). However, a small clinical study in adults shows that taking vitamin C up to 1000 mg daily for 2 months does not improve the response rate or decrease symptoms of depression in adults also taking citalopram when compared with citalopram alone (96708). Reasons for these conflicting results may relate to the age of the patients, study duration, or differences in antidepressant medication being taken. One clinical guideline also provisionally recommends against the use of oral vitamin C to treat patients with depression based on low-quality evidence (110318). Some research has also evaluated vitamin C intake for the prevention of depression. A secondary analysis of pre- and peri-menopausal adults enrolled in the Study of Women's Health Across the Nation (SWAN) program suggests that vitamin C intake is inversely associated with depressive symptoms. This association persisted regardless of age, race, physical activity, body mass index, antidepressant use or menopausal status (108083). The validity of these findings is limited due to the secondary nature of this study; additionally, follow-up time is unclear.
• Diabetes. It is unclear if oral vitamin C prevents diabetes. Some low-quality research suggests that vitamin C might improve glycemic control in patients with diabetes. Details: Population research has not found a link between dietary vitamin C and the risk of developing type 2 diabetes (14004). However, low certainty clinical research has found some benefit of taking vitamin C supplements for glycemic control. Two meta-analyses of several small, heterogeneous clinical studies in patients with type 2 diabetes show that taking vitamin C 200-3000 mg daily for 2-48 weeks reduces fasting blood glucose by approximately 11 mg/dL (112478) and glycated hemoglobin (HbA1c) by an average of 0.5% when compared with placebo, standard treatment, or no treatment (105461,112478). Subgroup analyses suggest that durations of supplementation longer than 12 weeks show greater glycemic benefit, and although one meta-analysis suggests there is no dose-response relationship (105461), another meta-analysis suggests that doses of vitamin C 1000 mg and higher are most beneficial for improving glycemic indices (112478). Some research has evaluated the effects of vitamin C supplementation on the lipid profile in patients with diabetes, with mixed findings. One meta-analysis of 17 small clinical studies shows that taking vitamin C 200-3000 mg daily for 2 to 48 weeks improves levels of triglycerides and total cholesterol, but not low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol. Subgroup analysis suggests that study durations of at least 12 weeks show greater benefit (106621). However, two other meta-analyses in patients with diabetes, one of 16 small heterogenous clinical studies and one of 11 small clinical studies, show no clinically important improvement in lipid levels after vitamin C supplementation (105461,105464).
• Dry mouth. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical trial in patients receiving radiotherapy for head and neck cancer shows that taking vitamin E 100 IU and vitamin C 500 mg twice daily for an average of 3 months improves dry mouth when compared to baseline (99080). The validity of these results is limited by the lack of comparison with a control group.
• Endometrial cancer. Increased dietary vitamin C has been linked to reduced risk of endometrial cancer. Details: Population research has found that intake of vitamin C from dietary sources is associated with a slightly decreased risk of endometrial cancer when compared with control. However, this benefit is not observed when results from a prospective cohort study are assessed (34578).
• Endometriosis. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical study in patients with endometriosis and pelvic pain shows that taking vitamin C 1000 mg and vitamin E 800 IU daily for 8 weeks improves dysmenorrhea, dyspareunia, and chronic pelvic pain scores when compared with placebo. Vitamin C and vitamin E supplementation also reduces some biochemical markers of oxidative stress when compared with placebo (106622). Additionally, a meta-analysis of 4 other, mostly small clinical studies in patients with endometriosis shows that taking vitamin C 1000 mg and vitamin E 800-1200 IU daily for 6-8 weeks reduces chronic pelvic pain and improves dysmenorrhea and dyspareunia when compared with placebo (114491).
• Endoscopy-associated adverse effects. It is unclear if a topical vitamin C spray reduces mucosal irritation in patients undergoing Lugol chromoendoscopy. Details: A small clinical trial in patients receiving a Lugol chromoendoscopy shows that spraying a vitamin C 2% solution after the application of the Lugol iodine 2% solution reduces the severity of mucosal irritation, heartburn, and pain when compared with using a normal saline spray after the Lugol iodine 2% solution (104030).
• Esophageal cancer. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Population research has found that higher dietary intake of vitamin C is associated with reduced odds of esophageal adenocarcinoma. A 50 gram increase in dietary vitamin C intake is associated with a 13% reduced odds of esophageal cancer (34551,98770). However, a meta-analysis of clinical research shows that taking a vitamin C supplement in combination with beta-carotene and vitamin E does not reduce the risk of esophageal cancer (34581).
• Exercise-induced asthma. Small clinical studies suggest that oral vitamin C may modestly improve symptoms in patients with exercise-induced asthma. Details: A meta-analysis of the available clinical research shows that vitamin C supplementation might reduce exercise-induced breathlessness when compared with placebo or control. However, the available research is of poor quality, and no clear conclusions can be drawn regarding its benefits for exercise-induced asthma (90409).
• Exercise-induced muscle damage. It is unclear if oral vitamin C is beneficial in exercise-induced muscle damage. Details: A small clinical study in healthy females shows that taking vitamin C 1000 mg before moderate intensity cycling does not prevent muscle damage when compared with placebo (99837). Another small clinical study in endurance-trained runners shows that taking vitamin C 1000 mg and vitamin E (as alpha-tocopherol) 235 mg 2 hours prior to an exercise protocol does not reduce delayed onset muscle soreness or improve other markers of exercise-induced muscle damage when compared with placebo (109961).
• Gallbladder disease. It is unclear if oral vitamin C reduces the risk of gallbladder disease. Details: Cross-sectional epidemiological evidence has found that vitamin C supplementation and increased vitamin C serum levels are associated with a decreased risk of developing gallbladder disease in females, but not males (5877).
• Gastric cancer. It is unclear if dietary or supplemental vitamin C reduces the risk of gastric cancer. Details: Most population research has not found an association between DIETARY intake of vitamin C and gastric cancer risk (9194,10822,10819,90083). Also, clinical research shows that taking vitamin C supplements in combination with other antioxidants does not reduce the risk of gastric cancer or precancerous gastric lesions (14447,34581,90085). However, some research suggests that it might be associated with a reduced risk for specific forms of gastric cancer (9838,90083). One clinical study shows that taking vitamin C orally 500 mg daily for 6 months after eradication of Helicobacter pylori infection decreases the incidence of precancerous changes in stomach tissue when compared with no treatment (10359). Also, other clinical research shows that taking vitamin C orally 1 gram daily helps promote the regression of precancerous gastric lesions in people at high risk for gastric cancer (2579). In 2009, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that vitamin C supplements may reduce the risk of gastric cancer. However, the FDA has concluded that it is highly uncertain that vitamin C supplements actually reduce the risk of gastric cancer (102332).
• Gastritis. There is limited evidence on the oral use of vitamin C in omeprazole-induced corpus gastritis. Details: A small clinical study shows that taking vitamin C orally 1200 mg daily along with omeprazole decreases corpus gastritis associated with omeprazole therapy in patients with H. pylori infection (10360).
• Gout. It is unclear if oral vitamin C helps to prevent or manage gout. Details: Population research in men has found that taking vitamin C 500-1500 mg daily from the diet and/or supplements is associated with up to a 34% reduced risk of gout when compared with less than 250 mg daily (16755). Also, men who ingest over 500 mg of vitamin C daily from the diet and supplements have serum uric acid levels that are slightly lower than men who consume less than 90 mg daily (16820). However, taking supplemental vitamin C 500 mg daily for 8 weeks does not seem to lower serum uric acid levels in patients who already have gout (90423).
• Hearing loss. There is limited evidence on the intravenous use of vitamin C in idiopathic sudden sensorineural hearing loss. It is unclear if dietary vitamin C intake can affect the risk of hearing loss. Details: A small clinical study in patients with idiopathic sudden sensorineural hearing loss shows that receiving intravenous high-dose vitamin C 200 mg/kg daily in combination with steroid therapy for 10 days, followed by oral vitamin C 2000 mg daily for 30 days, increases recovery rate two-fold and modestly improves hearing threshold levels when compared with receiving steroid therapy only (90417). In addition, population research in females has found that high dietary intake of vitamin C is associated with a 22% increased risk of developing self-reported hearing loss over a 22-year period when compared with low intake (109807).
• Heart transplant complications. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that a combination of vitamin C 500 mg and vitamin E 400 IU, taken twice daily for 1 year starting within the first 2 years after cardiac transplant, reduced the progression of vasculopathy as measured by intravascular ultrasonography (IVUS) when compared with placebo. This suggests that the combination may help slow the progression of CAV (82826).
• Hepatitis C. It is unclear if oral vitamin C is beneficial in patients with hepatitis C. Details: A small clinical study in patients with confirmed hepatitis C shows that taking vitamin C 1000 mg daily with conventional therapy (sofosbuvir plus daclatasvir) for 4 weeks improves serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and albumin when compared with conventional therapy alone (109463).
• HIV/AIDS. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small, low-quality study in men with HIV shows that taking vitamin C 250 mg daily in combination with vitamin A, beta-carotene, vitamin E, selenium, and coenzyme Q10 does not improve viral load, although it seems to improve markers of oxidative stress when compared to baseline. However, a 1000 mg dose of vitamin C, as well as higher doses of the other antioxidants, do not seem to provide any additional effect (9830).
• HIV transmission. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in HIV-positive mothers shows that taking vitamin B, vitamin C, and vitamin E daily during pregnancy and while breast-feeding for 20 weeks seems to reduce child mortality and HIV transmission through breast milk when compared with taking vitamin A (9801).
• Hyperphosphatemia. Intravenous vitamin C might be beneficial for reducing phosphate levels in patients with end-stage renal disease. Details: A small clinical study in hemodialysis patients with elevated phosphorus levels suggests that administering vitamin C 500 mg intravenously three times weekly for 8 weeks reduces phosphorus levels about seven-fold when compared with placebo (90414).
• Idiopathic interstitial pneumonia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with idiopathic pulmonary fibrosis, a form of idiopathic interstitial pneumonia, shows that taking a combination of vitamin C 250 mg every other day, vitamin D 50,000 IU daily, and vitamin E 200 IU daily for 12 weeks improves some, but not all, measures of lung function and reduces markers of inflammation and oxidative stress when compared to baseline (109464). The validity of these findings is limited by a lack of placebo control group.
• Infertility. It is unclear if oral vitamin C is beneficial in anovulatory females. Details: A very small clinical study suggests that taking vitamin C 400-1000 mg daily might improve fertility, resulting in ovulation and pregnancy in some anovulatory females, when compared to baseline (14018). The validity of these findings is limited by the small study size and lack of a comparator group. However, a very large observational study suggests that there is no association between dietary vitamin C intake and in-vitro fertilization (IVF) outcomes including good oocyte quality, embryo transfer success rates, clinical pregnancy rates, and successful term pregnancy rates in subfertile couples who are candidates for IVF (112097).
• Male infertility. It is unclear if oral or intravenous vitamin C is beneficial in males with infertility. Details: A meta-analysis of three small, low-quality clinical trials in males with infertility shows that taking vitamin C up to 1000 mg daily for up to 12 weeks can improve sperm count, motility, and vitality, but does not seem to increase semen volume or sperm concentration, when compared with control (109461). It is unclear if vitamin C can increase pregnancy rates, as these studies did not assess this outcome. A retrospective study in males with or without varicocele-related infertility has found that taking a specific combination product containing vitamin C 90 mg, zinc 10 mg, L-carnitine fumarate 1725 mg, acetyl-L-carnitine 500 mg, coenzyme Q10 20 mg, folic acid 0.2 mg, selenium 0.05 mg, and vitamin B12 0.015 mg (Proxeed Plus, Sigma-Tau) orally twice daily for 6 months improves sperm count, sperm concentration, and sperm motility when compared with baseline. Improvement in semen parameters were greatest in subjects with more severe varicoceles. The validity of this study is limited by the lack of a comparator group (111296).
• Mastalgia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in patients with mastalgia shows that taking a combination of vitamin C 100 mg, vitamin B12, and gamma-linolenic acid daily for 12 weeks does not improve the proportion of patients with minimal or no pain when compared with placebo (111059).
• Melasma. It is unclear if topical vitamin C is beneficial in patients with melasma. Details: A small clinical study in patients with bilateral symmetrically distributed facial melasma shows that applying 0.5 mL of vitamin C (Cosmotech, Alpha Medical Cosmotech) following dermapen microneedling every 2 weeks for 6 weeks is similarly effective to tranexamic acid for improving melasma severity and pigmented, but not vascular, findings on dermoscopic examination (106939). Additionally, a small clinical study in adults with melasma shows that applying 1 to 2 mL of 20% vitamin C solution following dermapen microneedling every 2 weeks for 8 weeks does not improve the degree of pigmentation when compared with topical metformin but does improve the degree of pigmentation when compared to baseline (115610).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral vitamin C is beneficial in patients with NAFLD. Details: A clinical study in patients with NAFLD shows that taking vitamin C 250 mg, 1000 mg, or 2000 mg daily for 12 weeks improves some biochemical markers of liver health and glucose metabolism when compared with baseline. However, the improvement from baseline was similar between groups (106942).
• Nonalcoholic steatohepatitis (NASH). Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research suggests vitamin C in combination with vitamin E might improve hepatic fibrosis in patients with NASH. However, it does not seem to decrease liver inflammation (14005).
• Non-Hodgkin lymphoma. It is unclear if oral vitamin C reduces the risk of developing diffuse large B-cell lymphoma. Details: In one population study, higher dietary or supplemental intake of vitamin C was associated with a reduced risk of diffuse large B-cell lymphoma, a type of non-Hodgkin lymphoma, when compared with lower intake in postmenopausal adults (90945).
• Oral cancer. It is unclear if oral vitamin C reduces the risk of developing oral cancer. Details: Population research has found that higher dietary intake of vitamin C is associated with a reduced risk of oral cancer (10821). However, clinical research has not shown benefit with oral vitamin C supplements. A small clinical trial in Japanese adults with oral leukoplakia shows that taking vitamin C 500 mg and beta-carotene 10 mg daily for 12 months does not reduce the development of oral cancer over 5 years when compared with vitamin C 50 mg daily (91384).
• Oral leukoplakia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in Japanese adults with oral leukoplakia shows that taking vitamin C 500 mg and beta-carotene 10 mg daily for 12 months does not improve leukoplakia symptoms or reduce the development of oral cancer over 5 years when compared with vitamin C 50 mg daily (91384).
• Osteoarthritis. It is unclear if dietary vitamin C reduces the risk of developing osteoarthritis. Details: Observational research has found that increased vitamin C from dietary sources is associated with a reduced risk of cartilage loss and disease progression in people with osteoarthritis (5881).
• Osteoporosis. It is unclear if dietary vitamin C improves bone density or reduces fracture risk in patients at risk for osteoporosis. Details: Some cross-sectional observational research in postmenopausal patients without a history of smoking or estrogen use has found that higher serum vitamin C levels are associated with lower bone mineral density (9828). However, other observational research in a larger population of adults at risk for osteoporosis has found that higher dietary vitamin C intake is not associated with fracture risk (104415).
• Ovarian cancer. Dietary vitamin C might not affect the risk of ovarian cancer. Details: Epidemiological research has found that dietary vitamin C intake is not linked with ovarian cancer risk (9193,102977).
• Pancreatitis. It is unclear if intravenous vitamin C is beneficial in patients with acute pancreatitis. Details: A small meta-analysis of clinical studies in patients with acute pancreatitis shows that intravenous vitamin C does not improve the odds of developing organ failure when compared with placebo or no intervention. Intravenous vitamin C seems to reduce hospital stay, but not in-hospital mortality (106941).
• Parkinson disease. Dietary vitamin C might not affect the risk of developing this condition. Details: Observational research has found that moderate or high dietary intake of vitamin C is not associated with a reduced risk of Parkinson disease (83316).
• Periodontitis. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is also unclear if dietary vitamin C reduces the risk of periodontitis. Details: A small clinical study in patients with moderate or advanced periodontitis shows that taking a supplement containing vitamin C 100 mg, alpha-lipoic acid, coenzyme Q10, cranberry extract, grapeseed extract, selenium, vitamin E, and zinc twice daily for 8 weeks in addition to standard nonsurgical therapy does not improve periodontal indices including bleeding on probing, gingival recession, plaque index, or inflammation, among others, when compared with placebo (111708). It is unclear if these effects are due to vitamin C, other ingredients, or the combination. There is also interest in whether dietary vitamin C intake impacts the risk of periodontitis. Observational research in US adults has found that individuals with dietary intake of vitamin C in the third quartile, but not the second or fourth quartiles, have lower odds of periodontitis when compared with vitamin C intake in the lowest quartile. Furthermore, the investigators identified a non-linear relationship between vitamin C intake and periodontitis risk, suggesting that individuals with intakes either much lower or much higher than 158 mg daily are at increased risk of developing periodontitis (109958).
• Peripheral arterial disease (PAD). It is unclear if dietary vitamin C helps to reduce the risk of developing PAD. Details: In females, epidemiological evidence has found that dietary intake of vitamin C of 142 mg daily or greater is associated with a 36% reduced risk of PAD when compared with lower intake levels of less than 80 mg daily (10130).
• Physical performance. It is unclear if oral vitamin C helps to improve physical performance and muscle strength in older people. Details: Population research has found that higher intake of dietary vitamin C is associated with improved physical performance and muscle strength in elderly people (14006). In contrast, a small clinical study in elderly men undergoing strength training shows that taking vitamin C 1000 mg and vitamin E 258IU daily for 12 weeks does not increase strength, and might even attenuate increases in muscle mass, when compared with strength training alone (96701).
• Pneumonia. It is unclear if oral or intravenous vitamin C helps to prevent or treat pneumonia. Details: A meta-analysis of 6 clinical studies in adults with community-acquired pneumonia shows that oral or intravenous vitamin C does not reduce overall mortality, hospital or intensive care unit length of stay, or the risk of mechanical ventilation when compared with control (114490). The interpretation of these results is limited by significant heterogeneity of the included studies. An earlier meta-analysis of two small, low-quality clinical studies in children shows that vitamin C does not seem to reduce the risk of pneumonia when compared with a control (104033).
• Postoperative recovery. It is unclear if oral or intravenous vitamin C improves postoperative recovery. Details: Meta-analyses of clinical research show that oral or intravenous vitamin C can shorten the duration of hospitalization after cardiac surgery when compared with control (91233,96703). However, other research shows no decrease in intensive care unit (ICU) or hospital stay with vitamin C supplementation (96705), while another clinical study in patients undergoing cardiac surgery with extracorporeal circulation shows that intravenous vitamin C administered during surgery and 48 hours after surgery reduces ICU stay and re-admission rates, wound infection, and hospital mortality, but not length of hospital stay, when compared with control (114492). A meta-analysis of 37 clinical trials in adults undergoing low- to high-risk noncardiac surgery (i.e., orthopedic, abdominal, gynecologic, or kidney transplantation), shows that receiving perioperative vitamin C, either orally or intravenously, does not improve duration of hospitalization or overall mortality when compared with control (108087).
• Postoperative pulmonary complications. It is unclear if intravenous vitamin C improves postoperative pulmonary complications. Details: A large, single-blind clinical study in patients with recent cardiac surgery with extracorporeal circulation shows that parenteral administration of vitamin C 50 mg/kg intraoperatively and 50 mg/kg every 6 hours for the next 48 hours, followed by oral vitamin C 2000 mg daily until 1-week post-discharge, reduces the incidence of postoperative pulmonary complications (PPC) by 22% and improves PPC severity scores when compared with control. Specifically, vitamin C reduces the incidence of pneumothorax, pleural effusion, pneumonia, and re-intubation and may ameliorate lung damage as suggested by higher Horowitz index when compared with control (114492). A small clinical trial in patients undergoing low-risk cardiac surgery shows that receiving intravenous vitamin C 1 gram 10 minutes after anesthesia might slightly reduce the rate of postoperative pulmonary complications when compared with receiving a saline injection (104034).
• Postoperative swelling. It is unclear if vitamin C reduces postoperative swelling after dental surgery. Details: A small observational study in adults undergoing surgery for wisdom tooth extraction shows that taking vitamin C 500 mg three times daily for 7 days in addition to standard treatment reduces swelling 7 days after surgery when compared with control. However, vitamin C does not seem to reduce swelling 3 days after surgery when compared with control, suggesting that longer durations are needed for anti-inflammatory effects (113664).
• Premature rupture of membranes (PROM). Oral vitamin C seems to reduce the risk of PROM in some patients; however, the addition of oral vitamin E seems to negate any benefit. Details: A meta-analysis of clinical research shows that taking vitamin C alone decreases the risk of both term and preterm PROM by 45% and 34%, respectively, when compared with placebo or control (96707). Another meta-analysis of clinical research shows that taking vitamin C during pregnancy decreases the risk of PROM by 43% and preterm PROM by 33%, but does not decrease the risk of term PROM, when compared with a control. While vitamin C was studied in doses of 100, 500, and 1000 mg daily, the decreased risk of PROM was only observed in studies of 100 mg daily (114493). A moderate-sized clinical study in patients with a history of PROM shows that taking vitamin C 100 mg daily, starting at 14 weeks' gestation, increases the gestational age at recurrent PROM by around 1 week and increases the gestational age at birth by around 1.3 weeks when compared with placebo (109960). Additionally, a meta-analysis of observational studies suggests that vitamin C levels in the blood tend to be lower in patients with PROM, particularly preterm PROM (114493). Taking vitamin C in combination with vitamin E, however, does not seem to reduce the risk of term or preterm PROM; some research suggests that it might even increase the risk of non-preterm PROM (83472,96707). However, other research shows that taking vitamin C 1000 mg plus vitamin E 400 IU daily, beginning at 24 to 34 weeks gestation and continuing until delivery, may help increase the latency period until delivery by 5 days and increase gestational age at delivery by almost 1 week when compared with placebo in patients with preterm PROM (90078).
• Pressure ulcers. It is unclear if oral vitamin C, when used alone or in combination with other ingredients, can improve the healing of pressure ulcers. Details: A small clinical study in institutionalized patients with pressure ulcers shows that taking vitamin C 500 mg twice daily for 12 weeks does not improve wound closure or increase healing rates when compared with vitamin C 10 mg twice daily (83617). Oral vitamin C has also been evaluated in combination with other ingredients for the treatment of grade II-IV pressure ulcers. Two small clinical studies in hospitalized patients with pressure ulcers shows that administering an oral nutritional supplement enriched with vitamin C, L-arginine, and zinc improves ulcer healing when compared with a standard diet (31953,87173). Also, clinical research in patients living in long-term care facilities shows that taking an oral nutritional supplement enriched in protein, vitamin C, L-arginine, and zinc daily for 9 weeks reduces ulcer area and decreases oozing when compared to baseline (32045). The validity of this finding is limited by the lack of a comparator group.
• Radiation proctopathy. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical study in patients with chronic radiation proctitis shows that vitamin C 500 mg plus vitamin E 400 IU three times daily might improve symptoms when compared with baseline (9825). The validity of these findings is limited by the lack of a comparator group.
• Renal cell carcinoma. It is unclear if increased dietary intake of vitamin C helps to reduce the risk of renal cell carcinoma. Details: Population research has found that increased dietary intake of vitamin C is associated with a 12% reduced risk of renal cell carcinoma (98779).
• Respiratory tract infections. It is unclear if oral vitamin C is beneficial for preventing respiratory tract infections or reducing the duration of these infections. Details: A meta-analysis of clinical research in children and adults shows that, when compared with placebo, oral vitamin C supplementation reduces the average number of symptomatic days per individual, but does not reduce the average symptom days per respiratory episode. Also, vitamin C intake does not reduce the incidence or severity of respiratory disease or improve recovery in hospitalized patients with respiratory tract infections (108077). The validity of this trial is limited by the high heterogeneity of included studies, which evaluated various vitamin C regimens, ranging from 100 mg to 8 grams daily, as preventive therapy or as an adjuvant to active treatment. A clinical study in children aged 3-10 years shows that taking vitamin C 50 mg in combination with a specific product (Lab4) containing Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium animalis subsp. lactis daily for 6 months reduces the incidence of cough and sore throat by 16% and 20%, respectively, when compared with placebo. However, it did not improve total symptoms, nasal congestion, nasal discharge, or sneezing. Also, aside from a 33% reduction in the average number of days with a sore throat, daily supplementation does not reduce the duration of individual symptoms or total symptoms (106943). It is unclear if these effects are due to vitamin C, the probiotics, or the combination.
• Restless legs syndrome (RLS). It is unclear if oral vitamin C helps to reduce symptoms of stress. Details: A small clinical study in hemodialysis patients with RLS shows that taking vitamin C 200 mg daily, alone or in combination with vitamin E 400 mg, for 8 weeks reduces the severity of RLS when compared with placebo (90093). More research is needed to determine if vitamin C is beneficial in treating RLS that is not associated with hemodialysis.
• Sunburn. Topical and oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking vitamin C orally in combination with vitamin E seems to prevent ultraviolet (UV) radiation-induced erythema (sunburn) (4715,4716). Vitamin C in combination with high dose oral RRR-alpha-tocopherol (natural vitamin E) seems to protect against skin inflammation after exposure to UV radiation (4715). Also, applying topical vitamin C in combination with topical vitamin E and melatonin seems to provide modest photoprotective effects when used prior to UV exposure. However, it has no effect when used during or after UV exposure (4713,4714).
• Stress. It is unclear if oral vitamin C helps to reduce symptoms of stress. Details: A small clinical study in healthy adults shows that taking vitamin C 3000 mg daily for 14 days modestly reduces blood pressure and subjective stress response to psychological stress when compared with placebo (10353).
• Stroke. Observational research has found that although taking vitamin C supplements does not seem to be beneficial, eating more vitamin C-rich food is linked with reduced risk of stroke. Details: Lower plasma levels of vitamin C have been associated with increased stroke risk (90408). Additionally, population research has found that higher dietary intake of vitamin C is associated with a 8% to 19% reduction in stroke risk when compared to lower intake (90408,109779). This reduction appears to be dose-dependent, with each 100 mg/day increase in dietary vitamin C intake associated with about a 17% reduction (90408). However, taking vitamin C supplements has not been found to be associated with reduced stroke risk (1449,90408).
• Tetanus. It is unclear if intravenous vitamin C helps to reduce symptoms of tetanus. Details: A low quality clinical trial in children and young adults with tetanus shows that intravenous vitamin C 1 gram daily along with conventional treatment reduces fatality when compared to control (21539).
• Tooth extraction. It is unclear if oral vitamin C is beneficial for reducing pain or improving healing after tooth extraction. Details: A small clinical study in healthy patients aged 14-41 years who are undergoing bilateral premolar extraction shows that taking vitamin C 200 mg three times daily, beginning immediately after extraction and continued for 10 days, improves pain on days 1-3, and may reduce mesio-distal wound size between days 1 and 7, when compared with placebo, but not when compared with vitamin C 500 mg three times daily. A dose of 500 mg three times daily did not improve pain scores or extraction wound healing when compared with placebo (108084). The validity of this trial is limited by the short duration of treatment; additionally, this study did not report baseline vitamin C levels.
• Urinary tract infections (UTIs). Although there is interest in using oral vitamin C for UTIs, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
• Vascular dementia. It is unclear if oral vitamin C reduces the risk of vascular dementia. Details: Population research has found that supplemental intake of vitamin C and vitamin E is associated with a reduced risk of vascular dementia in Japanese-American men (4636). However, when cases in which dementia was diagnosed prior to the study are excluded from data analysis, intake of vitamin C and vitamin E is not associated with a reduced risk of vascular dementia in these patients (9824).
• Wound healing. It is unclear if oral vitamin C improves the healing of chronic foot ulcers. It is also unclear if intravenous vitamin C improves healing of surgical wounds after total abdominal hysterectomy. Details: A very small clinical study in adults with chronic foot ulcers shows that taking slow-release vitamin C 500 mg daily for 8 weeks seems to result in a median of 100% ulcer healing, compared with a median of 14% ulcer healing in patients taking glucosamine 1000 mg daily (105456). This finding is limited due to the small and heterogeneous patient population, which included patients with diabetes, vascular disease, and/or vitamin C deficiency. Another small clinical study in patients undergoing total abdominal hysterectomy shows that administration of intravenous vitamin C 1 gram the night before surgery and 1 gram during surgery does not reduce the rate of surgical site infection or wound dehiscence when compared with placebo (109465). However, this study may not have been adequately powered to detect differences between groups. More evidence is needed to rate vitamin C for these uses.

(Read more about VITAMIN C)

LIKELY SAFE ...when used orally and appropriately. Boswellia serrata extract in doses up to 1000 mg daily has been safely used in several clinical trials lasting up to 6 months (1708,1709,12432,12434,12438,17948,17949,17950,91379)(100699,100713,102089,109568,115735). Boswellia serrata extract has been used with apparent safety at a dose of 2400 mg for up to 1 month (102092).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods (4912). There is insufficient reliable information available about the safety of using Boswellia serrata in medicinal amounts; avoid using.

(Read more about BOSWELLIA SERRATA)

POSSIBLY SAFE ...when used orally and appropriately. Doses up to 240 mg daily have been used safely for up to a year (6252,6253,10622,11457,18281,18284,91104,91105,91106,91111)(96449,103298). Higher doses up to 3200 mg daily have been used safely, short-term (18283,110546). ...when used topically and appropriately. Bromelain has been used safely as a debriding agent for up to 4 hours (18275,91113,103297,108148,108149,113899). Additionally, a retrospective cohort study in critically ill patients with severe burns suggests that use of bromelain as a debriding agent for up to 4 hours is not associated with a greater risk of bacteremia (113899).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about BROMELAIN)

LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Other clinical studies suggest that, when combined with vitamin D supplementation, calcium supplementation is not associated with an increased risk of CVD, CHD, or MI (93533,107231). Other analyses report conflicting results and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day, to consider total calcium intake from both dietary and supplemental sources (17484), and to combine calcium supplementation with vitamin D supplementation (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Other clinical studies suggest that, when combined with vitamin D supplementation, calcium supplementation is not associated with an increased risk of CVD, CHD, or MI (93533,107231). Other analyses report conflicting results and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day, to consider total calcium intake from both dietary and supplemental sources (17484), and to combine calcium supplementation with vitamin D supplementation (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

(Read more about CALCIUM)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Grapes and grape skin extracts have Generally Recognized As Safe (GRAS) status for use in foods in the US (4912).

POSSIBLY SAFE ...when the whole fruit of the grape, or extracts of the fruit, seed, or leaf, are used orally and appropriately in medicinal amounts. Grape seed extracts have been used with apparent safety in doses up to 200 mg daily for up to 11 months (9182,53016) and in doses up to 2000 mg daily for up to 3 months (53149,53190). Specific grape fruit extracts (Stilvid, Actafarma; Cognigrape, Bionap srl) have been used with apparent safety in doses up to 250-350 mg daily for 3-12 months or 700 mg daily for 6 months (53254,53256,96198). A specific grape leaf extract (AS 195, Antistax, Boehringer Ingelheim) has been used with apparent safety in doses up to 720 mg daily for up to 3 months (2538,52985,53005,53206). A preparation of dehydrated whole grapes, equivalent to 250 grams of fresh grapes daily, has also been used with apparent safety for up to 30 days (18228). A specific grape seed extract (Enovita; Indena SpA) 150 mg twice daily, standardized to provide at least 95% oligomeric proanthocyanins, has been used with apparent safety for up to 16 weeks (108091) ...when used topically and appropriately. Creams and ointments containing grape seed extract 2% or 5% have been used topically with apparent safety for up to 3 weeks (91539,100955). There is insufficient reliable information available about the safety of other grape plant parts when used topically.

CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods. Grapes and grape skin extracts have Generally Recognized As Safe (GRAS) status for use in foods in the US (4912). However, whole grapes should be eaten with caution in children aged 5 years and under. Whole grapes can be a choking hazard for young children (96193). To reduce the risk of choking, whole grapes should be cut in half or quartered before being given to children. There is insufficient reliable information available about the safety of grape when used in medicinal amounts in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods. There is insufficient reliable information available about the safety of medicinal amounts during pregnancy and breast-feeding; avoid using in amounts greater than what is commonly found in foods.

(Read more about GRAPE)

POSSIBLY SAFE ...when used orally and appropriately. Various proteolytic enzymes have been safely used orally in clinical research (716,964,965,968,969,6252,6253,10622,11457,18281,18284) (91104,91105,91106,91111,96449). Side effects are typically mild to moderate and most often include gastrointestinal effects. See specific monographs for more detailed information related to the safety of individual proteolytic enzymes. ...when used topically and appropriately. Various proteolytic enzymes have been safely used topically in clinical research (67835,67843,67845,91113). Some proteolytic enzymes might cause allergic reactions when used topically. See specific monographs for more detailed information related to the safety of individual proteolytic enzymes.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about PROTEOLYTIC ENZYMES (PROTEASES))

LIKELY SAFE ...when used orally in amounts found in foods, such as fruits and vegetables.

POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. Rutin has been used with apparent safety at doses of up to 600 mg daily for up to 12 weeks (6252,24560,91104,96766,105298). ...when applied topically as a cream (92236,99258,99260).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods. There is insufficient reliable information available about the use of supplemental rutin; avoid amounts greater than those found in foods.

(Read more about RUTIN)

POSSIBLY SAFE ...when used orally and appropriately, short-term. Serrapeptase seems to be safe when used in clinical trials lasting up to 4 weeks (13151,13152,13153). There is insufficient reliable information available about the safety of serrapeptase when used long-term.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about SERRAPEPTASE)

LIKELY SAFE ...when used orally and appropriately, short-term. Turmeric products providing up to 8 grams of curcumin have been safely used for up to 2 months (10453,11144,11150,17953,79085,89720,89721,89724,89728,101347)(81036,101349,107110,107116,107117,107118,107121,109278,109283,114899) and products providing up to 1500 mg of curcumin daily have been safely used for up to 12 months (114898) . Additionally, turmeric in doses up to 3 grams daily has been used with apparent safety for up to 3 months (102350,104146,104148,113357,114906). ...when used topically and appropriately (11148).

POSSIBLY SAFE ...when used as an enema, short-term. Turmeric extract in water has been used as a daily enema for up to 8 weeks (89729). ...when used topically as a mouthwash, short-term. A mouthwash containing 0.05% turmeric extract and 0.05% eugenol has been used safely twice daily for up to 21 days (89723).

PREGNANCY: LIKELY SAFE
when used orally in amounts commonly found in food.

PREGNANCY: LIKELY UNSAFE
when used orally in medicinal amounts; turmeric might stimulate the uterus and increase menstrual flow (12).

LACTATION: LIKELY SAFE
when used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of using turmeric in medicinal amounts during lactation.

(Read more about TURMERIC)

LIKELY SAFE ...when used orally, topically, intramuscularly, or intravenously and appropriately. Vitamin C is safe when taken orally in doses below the tolerable upper intake level (UL). Tell patients not to exceed the UL of 2000 mg daily (1959,4713,4714,4844). ...when used intravenously or intramuscularly and appropriately. Injectable vitamin C is an FDA-approved prescription product (15) and has been used with apparent safety in clinical trials up to 150 mg/kg daily for up to 4 days (114489) and up to 200 mg/kg daily for up to 2 days (114492).

POSSIBLY UNSAFE ...when used orally in excessive doses. Doses greater than the tolerable upper intake level (UL) of 2000 mg daily can significantly increase the risk of adverse effects such as osmotic diarrhea and gastrointestinal upset (4844).

CHILDREN: LIKELY SAFE
when used orally and appropriately (4844,10352,14443).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive amounts. Tell patients not to use doses above the tolerable upper intake level (UL) of 400 mg daily for children ages 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years. Higher doses can cause osmotic diarrhea and gastrointestinal upset (4844).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (4844).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. Tell patients over age 19 not to use doses exceeding the UL of 2000 mg daily when pregnant or breast-feeding and for those 14-18 years of age not to use doses exceeding 1800 mg daily when pregnant or breast-feeding. Higher doses can cause osmotic diarrhea and gastrointestinal upset. Large doses of vitamin C during pregnancy can also cause newborn scurvy (4844); avoid using.

(Read more about VITAMIN C)

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might increase the levels of CYP1A2 substrates.  Details In vitro research shows that Boswellia serrata gum resin inhibits CYP1A2 enzymes (21178).

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might increase the levels of CYP2C19 substrates.  Details In vitro research shows that Boswellia serrata gum resin inhibits CYP2C19 enzymes (21178).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might increase the levels of CYP2C9 substrates.  Details In vitro research shows that Boswellia serrata gum resin inhibits CYP2C9 enzymes (21178).

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might increase the levels of CYP2D6 substrates.  Details In vitro research shows that Boswellia serrata gum resin inhibits CYP2D6 enzymes (21178).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might increase or decrease the levels and clinical effects of CYP3A4 substrates.  Details In vitro research shows that Boswellia serrata gum resin inhibits CYP3A4 enzymes (21178). Other in vitro research shows that Boswellia serrata extract inhibits CYP3A4 enzymes at most concentrations, although it may modestly induce enzyme activity at low concentrations (111404).

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, Boswellia serrata might alter the effects of immunosuppressive drugs.  Details Some in vitro research suggests that Boswellia serrata extracts might inhibit mediators of autoimmune disorders such as leukotrienes and reduce production of antibodies and cell-mediated immunity (12432,12435,12437,12438). However, other in vitro research suggests that, when coupled with calcium ions, boswellic acids containing the keto group have immunostimulant properties within specific cell signaling pathways (21180).

(Read more about BOSWELLIA SERRATA)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Bromelain may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details There is one case report of a patient experiencing minor bruising while taking bromelain with naproxen (14806). Bromelain is thought to have antiplatelet activity (10639,14806,18285,18286,37234). Whether this interaction is of concern with topical bromelain is unclear. Interference with coagulation of burn wounds has been reported in a patient receiving bromelain-based enzymatic debridement. However, observational research has found that topical bromelain debridement is not associated with increases or decreases in laboratory markers of coagulation when compared with surgical debridement (110547).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, bromelain might increase levels of tetracycline antibiotics.  Details Laboratory research suggests that bromelain might increase the absorption of tetracycline antibiotics. However, a study in healthy adults reported no difference in tetracycline plasma levels when a 500 mg dose was taken with or without bromelain 80 mg (14296).

(Read more about BROMELAIN)

ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.  Details Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium reduces the absorption of bisphosphonates.  Details Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking calcipotriene with calcium might increase the risk for hypercalcemia.  Details Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.  Details Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.  Details Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.  Details Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of diltiazem.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of dolutegravir.  Details Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of elvitegravir.  Details Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption and effectiveness of levothyroxine.  Details Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.  Details Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption of quinolone antibiotics.  Details Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Calcium may reduce levels of raltegravir.  Details Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium seems to reduce the absorption of sotalol.  Details Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium seems to reduce the absorption of tetracycline antibiotics.  Details Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.  Details Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of verapamil.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

(Read more about CALCIUM)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape extracts may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro evidence suggests that grape extracts might decrease platelet aggregation (53017,53087).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Ingesting grape juice with cyclosporine can reduce cyclosporine absorption.  Details A small pharmacokinetic study in healthy young adults shows that intake of purple grape juice 200 mL along with cyclosporine can decrease the absorption of cyclosporine by up to 30% when compared with water (53177). Separate doses of grape juice and cyclosporine by at least 2 hours to avoid this interaction.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, grape juice might reduce the levels of CYP1A2 substrates.  Details A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of CYP1A2 (2539).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.  Details In vitro evidence shows that grape seed extract or grape juice might inhibit CYP2C9 enzymes (11094,53011,53089). However, a small pharmacokinetic study in healthy adults shows that drinking 8 ounces of grape juice once does not affect the clearance of flurbiprofen, a probe-drug for CYP2C9 metabolism (11094). The effects of continued grape juice consumption are unclear.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape seed extract may increase the levels of CYP2D6 substrates.  Details In vitro evidence suggests that grape seed extract might inhibit CYP2D6 enzymes (53011). However, this interaction has not been reported in humans.

CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape seed extract might increase the levels of CYP2E1 substrates.  Details In vitro and animal research suggests that grape seed proanthocyanidin extract inhibits CYP2E1 enzymes (52949). However, this interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D It is unclear if grape seed extract inhibits or induces CYP3A4; research is conflicting.  Details In vitro evidence suggests that grape seed extract might inhibit CYP3A4 enzymes (53089). However, evidence from animal research shows that grape seed extract may induce CYP3A4 in the liver (53011). So far, these interactions have not been reported in humans.

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, long-term intake of grape seed extract might decrease the effects of midazolam.  Details Animal research shows that subchronic ingestions of grape seed extract can increase the elimination of intravenous midazolam by increasing hepatic CYP3A4 activity. Single doses of grape seed extract do not appear to affect midazolam elimination (53011).

PHENACETIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grape juice might decrease phenacetin absorption.  Details A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of cytochrome P450 1A2 (CYP1A2) (2539).

(Read more about GRAPE)

(Read more about PROTEOLYTIC ENZYMES (PROTEASES))

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking rutin with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research suggests that rutin has hypoglycemic effects (105299).

(Read more about RUTIN)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking serrapeptase with drugs that have antiplatelet or anticoagulant effects might increase the risk of bruising and bleeding.  Details In vitro research shows that serrapeptase has fibrinolytic activity (13151,13152).

(Read more about SERRAPEPTASE)

ALKYLATING AGENTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric has antioxidant effects. Theoretically, this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.  Details In vitro research suggests that curcumin, a constituent of turmeric, inhibits mechlorethamine-induced apoptosis of breast cancer cells by up to 70%. Also, animal research shows that curcumin inhibits cyclophosphamide-induced tumor regression (96126). However, some in vitro research shows that curcumin does not affect the apoptosis capacity of etoposide. Also, other laboratory research suggests that curcumin might augment the cytotoxic effects of alkylating agents. Reasons for the discrepancies may relate to the dose of curcumin and the specific chemotherapeutic agent. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects (96125). More evidence is needed to determine what effect, if any, turmeric might have on alkylating agents.

AMLODIPINE (Norvasc) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Taking turmeric with amlodipine may increase levels of amlodipine.  Details Animal research shows that giving amlodipine 1 mg/kg as a single dose following the use of turmeric extract 200 mg/kg daily for 2 weeks increases the maximum concentration and area under the curve by 53% and 56%, respectively, when compared with amlodipine alone (107113). Additional animal research shows that taking amlodipine 1 mg/kg with a curcumin 2 mg/kg pretreatment for 10 days increases the maximum concentration and area under the curve by about 2-fold when compared with amlodipine alone (103099).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Turmeric may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs. However, research is conflicting.  Details Curcumin, a constituent of turmeric, has demonstrated antiplatelet effects in vitro (11143,81204,81271). Furthermore, two case reports have found that taking turmeric along with warfarin or fluindione was associated with an increased international normalized ratio (INR) (89718,100906). However, one clinical study in healthy volunteers shows that taking curcumin 500 mg daily for 3 weeks, alone or with aspirin 100 mg, does not increase antiplatelet effects or bleeding risk (96137). It is possible that the dose of turmeric used in this study was too low to produce a notable effect.

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking turmeric with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research and case reports suggest that curcumin, a turmeric constituent, can reduce blood glucose levels in patients with diabetes (79692,79984,80155,80313,80315,80476,80553,81048,81219). Furthermore, clinical research in adults with type 2 diabetes shows that taking curcumin 475 mg daily for 10 days prior to taking glyburide 5 mg decreased postprandial glucose levels for up to 24 hours when compared with glyburide alone, despite the lack of a significant pharmacokinetic interaction (96133). Other clinical studies in patients with diabetes show that taking curcumin daily can reduce blood glucose levels when compared with placebo (104149,114898,114900).

ANTITUMOR ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric has antioxidant effects. Theoretically, this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.  Details In vitro and animal research shows that curcumin, a constituent of turmeric, inhibits doxorubicin-induced apoptosis of breast cancer cells by up to 65% (96126). However, curcumin does not seem to affect the apoptosis capacity of daunorubicin. In fact, some research shows that curcumin might augment the cytotoxic effects of antitumor antibiotics, increasing their effectiveness. Reasons for the discrepancies may relate to the dose of curcumin and the chemotherapeutic agent. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects (96125). More evidence is needed to determine what effects, if any, antioxidants such as turmeric have on antitumor antibiotics.

CYTOCHROME P450 1A1 (CYP1A1) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase or decrease levels of drugs metabolized by CYP1A1. However, research is conflicting.  Details Most in vitro and animal research suggests that the turmeric constituent, curcumin, INHIBITS CYP1A1, primarily in the liver (15823,21495,80876,81411). However, some evidence from in vitro research suggests that curcumin may INDUCE CYP1A1 in the intestines (21500).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase levels of drugs metabolized by CYP1A2. However, research is conflicting.  Details In vitro and animal research show that the turmeric constituent, curcumin, inhibits CYP1A2 (15823,21497,81304). However, other in vitro research suggests that curcumin does not significantly affect CYP1A2 (22000).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric might increase levels of drugs metabolized by CYP3A4.  Details In vitro and animal research show that turmeric and its constituents curcumin and curcuminoids inhibit CYP3A4 (21497,21498,21499). Also, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking turmeric and cancer medications that are CYP3A4 substrates, including everolimus, ruxolitinib, ibrutinib, and palbociclib, and bortezomib (111644). In another case report, a transplant patient presented with acute nephrotoxicity and elevated tacrolimus levels after consuming turmeric powder at a dose of 15 or more spoonfuls daily for ten days prior. It was thought that turmeric increased levels of tacrolimus due to CYP3A4 inhibition (93544). Conversely, other in vitro research suggests that turmeric induces CYP3A4 activity, leading to reduced levels of CYP3A4 substrates (111404). However, this interaction has not been reported in humans.

DOCETAXEL (Taxotere) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase blood levels of oral docetaxel.  Details Animal research suggests that the turmeric constituent, curcumin, enhances the oral bioavailability of docetaxel (80999). However, the significance of this interaction is unclear, as this drug is typically administered intravenously in clinical settings.

ESTROGENS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, large amounts of turmeric might interfere with hormone replacement therapy through competition for estrogen receptors.  Details In vitro research shows that curcumin, a constituent of turmeric, displaces the binding of estrogen to its receptors (21486).

GLYBURIDE (Diabeta, others) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking turmeric and glyburide in combination might increase the risk of hypoglycemia.  Details Clinical research shows that taking curcumin 475 mg daily for 10 days prior to taking glyburide 5 mg increases blood levels of glyburide by 12% at 2 hours after the dose in patients with type 2 diabetes. While maximal blood concentrations of glyburide were not affected, turmeric modestly decreased postprandial glucose levels for up to 24 hours when compared to glyburide alone, possibly due to the hypoglycemic effect of turmeric demonstrated in animal research (96133).

HEPATOTOXIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase the risk of liver damage when taken with hepatotoxic drugs.  Details There is concern that turmeric might cause hepatotoxicity, especially when highly bioavailable formulations are used in high doses (103633,107122,109288,110221).

LOSARTAN (Cozaar) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase the effects of losartan.  Details Research in hypertensive rats shows that taking turmeric can increase the hypotensive effects of losartan (110897).

METHOTREXATE (Trexall, others) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might have additive effects when used with hepatotoxic drugs such as methotrexate.  Details In one case report, a 39-year-old female taking methotrexate, turmeric, and linseed oil developed hepatotoxicity (111644).

NORFLOXACIN (Noroxin) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase the effects and adverse effects of norfloxacin.  Details Animal research shows that taking curcumin, a turmeric constituent, can increase blood levels of orally administered norfloxacin (80863).

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase blood levels of OATP4C1 substrates.  Details In vitro research shows that the turmeric constituent curcumin competitively inhibits OATP4C1 transport. This transporter is expressed in the kidney and facilitates the renal excretion of certain drugs (113337). Theoretically, taking turmeric might decrease renal excretion of OATP substrates.

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might increase the absorption of P-glycoprotein substrates.  Details In vitro and animal research shows that curcuminoids and other constituents found in turmeric can inhibit P-glycoprotein expression and activity (21472,21473,21474,21475,21476,21477,21478,21479,21480)(21482,21484,111644).

PACLITAXEL (Abraxane, Onxol) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, turmeric might alter blood levels of paclitaxel, although any effect may not be clinically relevant.  Details Clinical research in adults with breast cancer receiving intravenous paclitaxel suggests that taking turmeric may modestly alter paclitaxel pharmacokinetics. Patients received paclitaxel on day 1, followed by either no treatment or turmeric 2 grams daily from days 2-22. Pharmacokinetic modeling suggests that turmeric reduces the maximum concentration and area under the curve of paclitaxel by 12.1% and 7.7%, respectively. However, these changes are not likely to be considered clinically relevant (108876). Conversely, animal research suggests that curcumin, a constituent of turmeric, enhances the oral bioavailability of paclitaxel (22005). However, the significance of this interaction is unclear, as this drug is typically administered intravenously in clinical settings.

SULFASALAZINE (Azulfidine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Turmeric might increase the effects and adverse effects of sulfasalazine.  Details Clinical research shows that taking the turmeric constituent, curcumin, can increase blood levels of sulfasalazine by 3.2-fold (81131).

TACROLIMUS (Prograf) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric might increase the effects and adverse effects of tacrolimus.  Details In one case report, a transplant patient presented with acute nephrotoxicity and elevated tacrolimus levels of 29 ng/mL. The patient previously had tacrolimus levels within the therapeutic range at 9.7 ng/mL. Ten days prior to presenting at the emergency room the patient started consumption of turmeric powder at a dose of 15 or more spoonfuls daily. It was thought that turmeric increased levels of tacrolimus due to cytochrome P450 3A4 (CYP3A4) inhibition (93544). In vitro and animal research show that turmeric and its constituent curcumin inhibit CYP3A4 (21497,21498,21499).

TALINOLOL Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Turmeric may reduce the absorption of talinolol in some situations.  Details Clinical research shows that taking curcumin for 6 days decreases the bioavailability of talinolol when taken together on the seventh day (80079). The clinical significance of this effect is unclear.

TAMOXIFEN (Nolvadex) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, turmeric might reduce the levels and clinical effects of tamoxifen.  Details In a small clinical trial in patients with breast cancer taking tamoxifen 20-30 mg daily, adding curcumin 1200 mg plus piperine 10 mg three times daily reduces the 24-hour area under the curve of tamoxifen and the active metabolite endoxifen by 12.8% and 12.4%, respectively, as well as the maximum concentrations of tamoxifen, when compared with tamoxifen alone. However, in the absence of piperine, the area under the curve for endoxifen and the maximum concentration of tamoxifen were not significantly reduced. Effects were most pronounced in patients who were extensive cytochrome P450 (CYP) 2D6 metabolizers (107123).

TOPOISOMERASE I INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric has antioxidant effects. There is some concern that this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.  Details In vitro research shows that curcumin, a constituent of turmeric, inhibits camptothecin-induced apoptosis of breast cancer cells by up to 71% (96126). However, other in vitro research shows that curcumin augments the cytotoxic effects of camptothecin. Reasons for the discrepancies may relate to the dose of curcumin and the chemotherapeutic agents. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects (96125). More evidence is needed to determine what effect, if any, turmeric might have.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Turmeric might increase the risk of bleeding with warfarin.  Details One case of increased international normalized ratio (INR) has been reported for a patient taking warfarin who began taking turmeric. Prior to taking turmeric, the patient had stable INR measurements. Within a few weeks of starting turmeric supplementation, the patient's INR increased to 10 (100906). Additionally, curcumin, the active constituent in turmeric, has demonstrated antiplatelet effects in vitro (11143,81204,81271), which may produce additive effects when taken with warfarin.

(Read more about TURMERIC)

ACETAMINOPHEN (Tylenol, others) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Probable •  Level of Evidence = B High-dose vitamin C might slightly prolong the clearance of acetaminophen.  Details A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases (6451). This effect is not likely to be clinically significant.

ALKYLATING AGENTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.  Details The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.  Details Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption (10549,10550,10551,21556). In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely (10549). Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.

ANTITUMOR ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.  Details The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.

ASPIRIN Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = B Acidification of the urine by vitamin C might increase aspirin levels.  Details It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction is not clinically significant.

CHOLINE MAGNESIUM TRISALICYLATE (Trilisate) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = B Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.  Details It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046,4531). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Vitamin C might increase blood levels of estrogens.  Details Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products (129,130,11161). It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall (129,11161). When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements (11161). Monitor these patients for estrogen-related side effects.

FLUPHENAZINE (Prolixin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, vitamin C might decrease levels of fluphenazine.  Details In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started (11017). The mechanism is not known, and there is no further data to confirm this interaction.

INDINAVIR (Crixivan) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Vitamin C can modestly reduce indinavir levels.  Details One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown (11300,93578).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Vitamin C can increase levothyroxine absorption.  Details Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH (102978).

NIACIN Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = A Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.  Details A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease (7388,11537). It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.

SALSALATE (Disalcid) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = B Acidification of the urine by vitamin C might increase salsalate levels.  Details It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D High-dose vitamin C might reduce the levels and effectiveness of warfarin.  Details Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption (11566). There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time (9804,9806). Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant (9805,9806,11566,11567). However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR) (90942). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.

(Read more about VITAMIN C)

General ...Orally, Boswellia serrata extract is generally well-tolerated. For information on the safety of Boswellia serrata when applied topically or used as aromatherapy, see the Frankincense monograph.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, headache, heartburn, itching, nausea.
Serious Adverse Effects (Rare):
Orally: Large amounts of Boswellia serrata gum resin can cause bezoar formation.

Dermatologic ...Orally, Boswellia serrata extract (5-Loxin) has been associated with itching at doses of 100-250 mg daily (17948).

Gastrointestinal ...Orally, Boswellia serrata extract may cause diarrhea, nausea, abdominal pain, and heartburn (1708,12432,12438,17948,17949,17950,21149,109567,114685). A case of a large gastrointestinal bezoar has been reported in a 17-year-old female who chewed and swallowed large quantities of boswellia gum resin (Boswellia species not specified) for celiac disease (36914).

Musculoskeletal ...Orally, Boswellia serrata extract (5-Loxin) has been associated with one case of foot edema and four cases of generalized weakness in one clinical study (17948).

Neurologic/CNS ...Orally, Boswellia serrata extract may cause dizziness, headache, and vertigo. In one clinical study, nearly 11% of patients taking a specific Boswellia serrata extract (K-Vie) reported headache. Dizziness and vertigo were also reported, but at lower rates (109567). In another study, headache was reported in one patient taking a specific Boswellia serrata extract (5-Loxin) (17948).

Psychiatric ...Orally, one case of mania is reported in a 73-year-old male who took Boswellia powder mixed with honey for 3 days. The patient recovered after hospitalization and treatment with olanzapine (110526).

(Read more about BOSWELLIA SERRATA)

General ...Orally, bromelain seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, flatulence, gastric upset, headache.
Topically: Pruritus, urticaria.

Dermatologic ...Topically, bromelain may cause dermal allergic reactions including urticaria, pruritus, and skin swelling (9184). Redness, swelling, burning, pain at the application site, and cellulitis have also been reported rarely (108148,113513). In one case, a fixed drug eruption with pruritis near the groin was reported in a 33-year-old male taking bromelain 50 mg orally daily for 10 days. After discontinuation of bromelain and treatment with topical corticosteroid, the lesion resolved. Upon re-challenge with bromelain, the lesion reappeared in the same area (103300).
In another case report, a 61-year-old male with a history of chronic lower leg ulceration secondary to chronic venous hypertension and recurrent deep vein thrombosis on rivaroxaban presented with a deep-dermal burn on his lower calf. Bromelain-based topical enzymatic debridement agent Nexobrid 2 grams was applied to the burn site. Thirty minutes later, the patient experienced two instances of hemorrhage at the site of debridement. The patient was stabilized and treated with fluids, packed red cells, and tranexamic acid, and then the Nexobrid was removed (111656). Caution should be used in patients with underlying coagulopathies.

Gastrointestinal ...Orally, bromelain may cause gastrointestinal disturbances, including diarrhea, nausea, vomiting, flatulence, and abdominal pain (9184,18274,18282,96216,113513).

Immunologic ...Immunoglobulin E (IgE)-mediated allergic reactions to bromelain may occur (9184).
If inhaled, bromelain may cause sensitization and allergic reactions such as asthma (37199,37215,37233). In case reports of occupational inhalation of bromelain, additional allergic symptoms included difficulty swallowing, throat itching, eye irritation, and rhinitis (37214).

(Read more about BROMELAIN)

General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

(Read more about CALCIUM)

General ...Orally, the whole fruit, as well as the seed, fruit, and leaf extracts, seem to be well tolerated. Topically, grape seed extracts seem to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, dry mouth, dyspepsia, headache, joint pain, and nausea.
Serious Adverse Effects (Rare):
Orally: Anaphylaxis to grape skin has been reported.

Dermatologic ...Orally, mild hair thinning has been reported in a patient taking a specific grape leaf extract AS195 KG) (2538). Urticaria (hives) has also been reported with this same extract (53206). Cases of contact dermatitis have been reported in grape workers, including those working in California vineyards (53270,53272,53275).

Gastrointestinal ...Orally, abdominal pain and nausea have been reported with use of grape seed extract, but these effects typically occur at rates similar to placebo (9182,13162). In a case report of a 57-year-old man, intermittent nausea, vomiting, and diarrhea occurred over a 10-day period and improved once grape seed extract was stopped (96764). Gastrointestinal adverse effects have also been reported with use of a different grape seed extract (Entelon, Hanlim Pharm). However, the specific types of gastrointestinal effects were not described (100954). A specific grape leaf extract AS195 (Antistax, Boehringer Ingelheim Pharma GmbH & Co. KG) has reportedly caused flatulence, mild constipation, gastrointestinal discomfort, diarrhea, dyspepsia, dry mouth, and retching (2538,52985,53206). Diarrhea, gastrointestinal distress, indigestion, and aversion to taste have been reported with use of Concord grape juice (52972,53166,53175,53181,53199). Loose stools have been reported in a clinical trial of grape pomace (99270). Bowel obstruction caused by intact grapes and grape seeds has been described in case reports (53241,53284,53278). Excessive consumption of grapes, dried grapes, raisins, or sultanas might cause diarrhea due to laxative effects (4201).

Hematologic ...Orally, one case of leg hematoma following a minor trauma was reported in a person using grape leaf extract (2538). Also, one case of bruising was reported in a person drinking Concord grape juice daily for 2 weeks (52972).

Immunologic ...Orally, there is one report of an anaphylactic reaction to oral grape skin extract, which included urticaria and angioedema (4073).

Musculoskeletal ...Orally, musculoskeletal disorders, including back pain, have been reported with use of a specific grape leaf extract AS195 KG) (2538,53206). Joint pain and lumbago have been reported with use of grape seed extract, but these effects occur at rates similar to placebo (91541).

Neurologic/CNS ...Orally, headache has been reported with use of grape seed extract, but this effect occurs at rates similar to placebo (9182,91541). A specific grape leaf extract AS195 (Antistax, Boehringer Ingelheim Pharma GmbH & Co. KG) has reportedly caused dizziness, tiredness, headache, and sleep problems (2538,53206). As a class, nervous system adverse effects have been reported with use of a specific grape seed extract (Entelon, Hanlim Pharm). However, the specific types of adverse neurologic effects were not described (100954).

Ocular/Otic ...Orally, ocular adverse effects have been reported with use of a specific grape seed extract (Entelon, Hanlim Pharm). However, the specific types of ocular adverse effects were not described (100954).

Pulmonary/Respiratory ...Orally, nasopharyngitis and oropharyngeal pain have been reported with use of a specific grape leaf extract AS195 KG) (53206). Sore throat, cough, allergic rhinitis, and nasopharyngitis have been reported with use of grape seed extract, but these effects occur at rates similar to placebo (9182,91541). One case report describes a 16-year-old female who developed increased levels of immunoglobulin E (IgE) following skin-prick exposure to grape vine pollen, as well as positive test responses following bronchial and conjunctival provocation (53301). Reduced forced vital capacity has been described in California grape workers (53080,53081). Occupational eosinophilic lung was diagnosed in a grape grower with a history of asthma. Respiratory exposure to sulfites in grape was implicated as the cause of the adverse reaction (53285).

Other ...Orally, grape products can cause adverse effects due to contamination with pesticides or mycotoxins. Some evidence has shown that pesticides used in vineyards may remain on grape surfaces post-harvesting. For example, the fungicide folpet sprayed on grapevines has been shown to remain on the grape surface. Although there was minimal penetration of the epicuticular wax, it showed high resistance to washing (52935). Carbaryl has been identified in over 58% of juice samples collected in Canada. This pesticide reportedly occurred more frequently in grape than in other juices. However, estimates of short-term intake were below proposed acute reference doses (53003).
Ochratoxin A is a mycotoxin that is suspected to be nephrotoxic, teratogenic, hepatotoxic and carcinogenic and has been identified in grape juice, frozen grape pulps, and red and white wine sold in Rio de Janeiro, Brazil. However, the highest levels identified in grape products were lower than the established virtually safe dose of 5 ng/kg of body weight daily (53010,53004). Ochratoxin A has also been identified in red, but not white, grape juice marketed in Switzerland, Canada, and the U.S. (53292,53020).

(Read more about GRAPE)

General ...Orally, proteolytic enzymes are generally well tolerated. See specific monographs for detailed safety information related to individual proteolytic enzymes.
Most Common Adverse Effects:
Orally: Gastrointestinal upset.
Serious Adverse Effects (Rare):
Topically: Allergic reactions.

Gastrointestinal ...Orally, some patients taking proteolytic enzymes may have gastrointestinal complaints (101517).

Immunologic ...Proteolytic enzymes are commonly found in laundry detergents and pre-spotter products. Rarely, protease specific IgE positive tests possibly related to these products have occurred. Exposure may be airborne or topical (102705). In addition, in case reports, occupational exposure to the airborne proteolytic enzyme pepsin has resulted in allergic rhinoconjunctivitis or asthma (102706,102707).

(Read more about PROTEOLYTIC ENZYMES (PROTEASES))

General ...Orally, rutin is generally well tolerated.

Dermatologic ...Orally, rutin may cause flushing and rashes in some people (313).

Gastrointestinal ...Orally, rutin may cause gastrointestinal disturbance in some people (313).

Neurologic/CNS ...Orally, rutin may cause headache in some people (313).

(Read more about RUTIN)

General ...Orally, serrapeptase seems to be well-tolerated.
Most Common Adverse Effects:
Orally: Epigastric pain, gastrointestinal upset, nausea.
Serious Adverse Effects (Rare):
Orally: Bullous pemphigoid

Gastrointestinal ...Orally, some patients have reported experiencing epigastric pain, gastrointestinal upset, and nausea; however, these side effects appear to occur at the same rate as placebo (13152).

Immunologic ...There is a case report of bullous pemphigoid, an autoimmune subepidermal dermatosis, in an elderly man who took serrapeptase (13154).

(Read more about SERRAPEPTASE)

General ...Orally and topically, turmeric is generally well tolerated.
Most Common Adverse Effects:
Orally: Constipation, dyspepsia, diarrhea, distension, gastroesophageal reflux, nausea, and vomiting.
Topically: Curcumin, a constituent of turmeric, can cause contact urticaria and pruritus.

Cardiovascular ...Orally, a higher dose of turmeric in combination with other ingredients has been linked to atrioventricular heart block in one case report. It is unclear if turmeric caused this adverse event or if other ingredients or a contaminant were the cause. The patient had taken a combination supplement containing turmeric 1500-2250 mg, black soybean 600-900 mg, mulberry leaves, garlic, and arrowroot each about 300-450 mg, twice daily for one month before experiencing atrioventricular heart block. Heart rhythm normalized three days after discontinuation of the product. Re-administration of the product resulted in the same adverse effect (17720).

Dermatologic ...Following occupational and/or topical exposure, turmeric or its constituents curcumin, tetrahydrocurcumin, or turmeric oil, can cause allergic contact dermatitis (11146,79270,79470,79934,81410,81195). Topically, curcumin can also cause rash or contact urticaria (79985,97432,112117). In one case, a 60-year-old female, with no prior reactivity to regular oral consumption of turmeric products, developed urticaria after topical application of turmeric massage oil (97432). A case of pruritus has been reported following topical application of curcumin ointment to the scalp for the treatment of melanoma (11148). Yellow discoloration of the skin has been reported rarely in clinical research (113356). Orally, curcumin may cause pruritus, but this appears to be relatively uncommon (81163,97427,104148,114899). Pitting edema may also occur following oral intake of turmeric extract, but the frequency of this adverse event is less common with turmeric than with ibuprofen (89720). A combination of curcumin plus fluoxetine may cause photosensitivity (89728).

Gastrointestinal ...Orally, turmeric can cause gastrointestinal adverse effects (107110,107112,112118), including constipation (81149,81163,96135,113355), flatulence and yellow, hard stools (81106,96135), nausea and vomiting (10453,17952,89720,89728,96127,96131,96135,97430,112117,112118), diarrhea or loose stool (10453,17952,18204,89720,96135,110223,112117,112118,114898,114899), dyspepsia (17952,89720,89721,96161,112118), gastritis (89728), distension and gastroesophageal reflux disease (18204,89720), abdominal fullness and pain (81036,89720,96161,97430,114898,114899), epigastric burning (81444), and tongue staining (89723).

Hepatic ...Orally, turmeric has been associated with liver damage, including non-infectious hepatitis, cholestasis, and hepatocellular liver injury. There have been at least 70 reports of liver damage associated with taking turmeric supplements for at least 2 weeks and for up to 14 months. Most cases of liver damage resolved upon discontinuation of the turmeric supplement. Sometimes, turmeric was used concomitantly with other supplements and medications (99304,102346,103094,103631,103633,103634,107122,109288,110221). The Drug-Induced Liver Injury Network (DILIN) has identified 10 cases of liver injury which were considered to be either definitely, highly likely, or probably associated with turmeric; none of these cases were associated with the use of turmeric in combination with other potentially hepatotoxic supplements. Most patients (90%) presented with hepatocellular pattern of liver injury. The median age of these case reports was 56 years and 90% identified as White. In these case reports, the carrier frequency on HLAB*35:01 was 70%, which is higher than the carrier frequency found in the general population. Of the ten patients, 5 were hospitalized and 1 died from liver injury (109288).
It is not clear if concomitant use with other supplements or medications contributes to the risk for liver damage. Many case reports did not report turmeric formulation, dosing, or duration of use (99304,103094,103631,103634,109288). However, at least 10 cases involved high doses of curcumin (250-1812.5 mg daily) and the use of highly bioavailable formulations such as phytosomal curcumin and formulations containing piperine (102346,103633,107122,109288,110221).

Neurologic/CNS ...Orally, turmeric has been associated with headache and vertigo (81163,114898).

Psychiatric ...Orally, the turmeric constituent curcumin or a combination of curcumin and fluoxetine can cause giddiness, although this event seems to be uncommon (81206,89728).

Renal ...Orally, turmeric has been linked to one report of kidney failure, although the role of turmeric in this case is unclear. A 69-year-old male developed kidney failure related to calcium oxalate deposits in the renal tubules following supplementation with turmeric 2 grams daily for 2 years as an anti-inflammatory for pelvic pain. While turmeric is a source of dietary oxalates, pre-existing health conditions and/or chronic use of antibiotics may have contributed to the course of disease (113343).

Other ...There is a single case report of death associated with intravenous use of turmeric. However, analysis of the treatment vial suggests that the vial contained only 0.023% of the amount of curcumin listed on the label. Also, the vial had been diluted in a solution of ungraded polyethylene glycol (PEG) 40 castor oil that was contaminated with 1.25% diethylene glycol. Therefore the cause of death is unknown but is unlikely to be related to the turmeric (96136).

(Read more about TURMERIC)

General ...Orally, intravenously, and topically, vitamin C is well-tolerated.
Most Common Adverse Effects:
Orally: Abdominal cramps, esophagitis, heartburn, headache, osmotic diarrhea, nausea, vomiting. Kidney stones have been reported in those prone to kidney stones. Adverse effects are more likely to occur at doses above the tolerable upper intake level of 2 grams daily.
Topically: Irritation and tingling.
Serious Adverse Effects (Rare):
Orally: There have been rare case reports of carotid inner wall thickening after large doses of vitamin C.
Intravenously: There have been case reports of hyperoxalosis and oxalate nephropathy following high-dose infusions of vitamin C.

Cardiovascular ...Evidence from population research has found that high doses of supplemental vitamin C might not be safe for some people. In postmenopausal adults with diabetes, supplemental vitamin C intake in doses greater than 300 mg per day is associated with increased risk of cardiovascular mortality. However, dietary intake of vitamin C is not associated with this risk. Also, vitamin C intake is not associated with an increased risk of cardiovascular mortality in patients without diabetes (12498).
Oral supplementation with vitamin C has also been associated with an increased rate of carotid inner wall thickening in men. There is preliminary evidence that supplemental intake of vitamin C 500 mg daily for 18 months can cause a 2.5-fold increased rate of carotid inner wall thickening in non-smoking men and a 5-fold increased rate in men who smoked. The men in this study were 40-60 years old (1355). This effect was not associated with vitamin C from dietary sources (1355).
There is also some concern that vitamin C may increase the risk of hypertension in some patients. A meta-analysis of clinical research suggests that, in pregnant patients at risk of pre-eclampsia, oral intake of vitamin C along with vitamin E increases the risk of gestational hypertension (83450). Other clinical research shows that oral intake of vitamin C along with grape seed polyphenols can increase both systolic and diastolic blood pressure in hypertensive patients (13162). Three cases of transient hypotension and tachycardia during intravenous administration of vitamin C have also been reported (114490).

Dental ...Orally, vitamin C, particularly chewable tablets, has been associated with dental erosion (83484).

Dermatologic ...Topically, vitamin C might cause tingling or irritation at the site of application (6166). A liquid containing vitamin C 20%, red raspberry leaf cell culture extract 0.0005%, and vitamin E 1% (Antioxidant and Collagen Booster Serum, Max Biocare Pty Ltd.) has been reported to cause mild tingling and skin tightness (102355). It is unclear if these effects are due to vitamin C, the other ingredients, or the combination.

Gastrointestinal ...Orally, the adverse effects of vitamin C are dose-related and include nausea, vomiting, esophagitis, heartburn, abdominal cramps, gastrointestinal obstruction, and diarrhea. Doses greater than the tolerable upper intake level (UL) of 2000 mg per day can increase the risk of adverse effects such as osmotic diarrhea and severe gastrointestinal upset (3042,4844,96707,104450,114493,114490). Mineral forms of vitamin C, such as calcium ascorbate (Ester-C), seem to cause fewer gastrointestinal adverse effects than regular vitamin C (83358). In a case report, high dose intravenous vitamin C was associated with increased thirst (96709).

Genitourinary ...Orally, vitamin C may cause precipitation of urate, oxalate, or cysteine stones or drugs in the urinary tract (10356). Hyperoxaluria, hyperuricosuria, hematuria, and crystalluria have occurred in people taking 1 gram or more per day (3042,90943). Supplemental vitamin C over 250 mg daily has been associated with higher risk for kidney stones in males. There was no clear association found in females, but the analysis might not have been adequately powered to evaluate this outcome (104029). In people with a history of oxalate kidney stones, supplemental vitamin C 1 gram per day appears to increase kidney stone risk by 40% (12653). A case of hematuria, high urine oxalate excretion, and the presence of a ureteral stone has been reported for a 9-year-old male who had taken about 3 grams of vitamin C daily since 3 years of age. The condition resolved with cessation of vitamin C intake (90936).

Hematologic ...Prolonged use of large amounts of vitamin C can result in increased metabolism of vitamin C; subsequent reduction in vitamin C intake may precipitate the development of scurvy (15). In one case, a patient with septic shock and a large intraperitoneal hematoma developed moderate hemolysis and increased methemoglobin 12 hours after a high-dose vitamin C infusion. The patient received a blood transfusion and the hemolysis resolved spontaneously over 48 hours (112479).

Neurologic/CNS ...Orally, the adverse effects of vitamin C are dose-related and include fatigue, headache, insomnia, and sleepiness (3042,4844,83475,83476).

Renal ...Hyperoxalosis and oxalate nephropathy have been reported following high-dose infusions of vitamin C. Hyperoxalosis and acute kidney failure contributed to the death of a 76-year-old patient with metastatic adenocarcinoma of the lung who received 10 courses of intravenous infusions containing vitamins, including vitamin C and other supplements over a period of 1 month. Dosages of vitamin C were not specified but were presumed to be high-dose (106618). In another case, a 34-year-old patient with a history of kidney transplant and cerebral palsy was found unresponsive during outpatient treatment for a respiratory tract infection. The patient was intubated for acute hypoxemic respiratory failure, initiated on vasopressors, hydrocortisone, and antibacterial therapy, and received 16 doses of vitamin C 1.5 grams. Serum creatinine level peaked at greater than 3 times baseline and the patient required hemodialysis for oliguria and uncontrolled acidosis. Kidney biopsy revealed oxalate nephropathy with concomitant drug-induced interstitial nephritis (106625). In another case, a 41-year-old patient with a history of kidney transplant presented with fever, nausea, and decreased urine output 4 days after receiving intravenous vitamin C 7 grams for urothelial carcinoma. Serum creatinine levels increased from 1.7 mg/dL to 7.3 mg/dL over those 4 days, and hemodialysis was initiated 3 days after admission due to anuria. Renal biopsy confirmed the diagnosis of acute oxalate nephropathy (109962).

Other ...Intravenously, hypernatremia and falsely elevated ketone levels is reported in a patient with septic shock and chronic kidney disease after a high-dose vitamin C infusion. The hypernatremia resolved over 24 hours after cessation of the infusion (112479).

(Read more about VITAMIN C)