NK-Stim by Ortho Molecular Products

NatMed Pro Brand Evidence-based Rating (NMBER)

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Serving Size 2 Capsule(s)

Ingredients	Amount Per Serving
Zinc (as TRAACS Zinc Bisglycinate Chelate) (Zinc (Form: as TRAACS Zinc Bisglycinate Chelate) )	10 mg
Arabinogalactan Heartwood (from Larch Tree) (Arabinogalactan Heartwood (Form: from Larch Tree) )	610 mg
Olive leaf extract (leaf) (standardized to contain 20% Oleuropein) (Olive leaf extract (Form: standardized to contain 20% Oleuropein) PlantPart: leaf )	400 mg
Aloe vera leaf gel extract (Aloe vera ) (leaf)	130 mg

Other Ingredients

natural Vegetable Capsules, Microcrystalline Cellulose, Magnesium Stearate

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Effectiveness view details

Below is general information about the effectiveness of the known ingredients contained in the product NK-Stim. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe vera leaf gel extract)

POSSIBLY EFFECTIVE

Acne. Topical aloe gel may reduce acne lesions when used with topical tretinoin in children and adults with acne. Details: One clinical trial in children and adults with acne shows that topical application of a gel containing aloe 50% in the morning and evening, in addition to topical application of tretinoin 0.025% cream and twice daily cleansing with a medical soap, improves acne lesions by approximately 35% more than using the same treatments without aloe (90124).
Burns. Topical aloe gel or cream may reduce healing time in patients with superficial or partial thickness burns. Details: A meta-analysis of four small clinical trials in patients with second-degree burns shows that use of topical aloe vera reduces time to healing by about 4.4 days when compared to control groups treated with silvadene, silver sulfadiazine, or gauze containing 0.5% chlorhexidine acetate (110209). Most clinical research shows that applying aloe gel or cream topically up to twice daily reduces healing time when compared with silver sulfadiazine (19771,110210,110212), framycetin (19775), vaseline gauze (19773), or placebo (101,97320) in patients with superficial or partial thickness burns. Topical application of aloe cream up to twice daily might also decrease wound size when compared with silver sulfadiazine and framycetin (19771,19775). In addition, some clinical research in patients with burns caused by sulfur mustard shows that applying cream containing aloe and olive oil twice daily for 6 weeks improves pruritus similarly to betamethasone 0.1% cream and may lead to further reductions in excoriation and fissure (19768). However, some preliminary clinical research shows that applying fresh aloe mucilage or aloe extract daily is no more effective than silver sulfadiazine for reducing wound healing time in patients with superficial or partial thickness burns (19774,19776).
Constipation. Oral aloe latex may improve symptoms in patients with constipation; however, the U.S. Food and Drug Administration (FDA) has banned the use of aloe latex as a laxative due to safety concerns. Details: Taking aloe latex 100-200 mg daily or aloe extract 50 mg as a stimulant laxative seems to relieve constipation due to the cathartic effects of the anthraquinones in the aloe (4,5,8). Taking 1-3 capsules of a formulation containing aloe 150 mg, celandine 300 mg, and psyllium 50 mg also seems to improve stool consistency and the mean number of stools in patients with chronic constipation when compared with placebo (19747). However, in 2002, the U.S. FDA banned the use of aloe latex for constipation due to safety concerns (8229,8443).
Diabetes. Oral aloe may reduce blood glucose and glycated hemoglobin (HbA1c) in patients with diabetes. It may be most effective in patients with fasting blood glucose levels of 200 mg/dL or greater. Details: Most clinical research in adults with prediabetes and diabetes shows that taking aloe vera orally can reduce fasting blood glucose by 30-47 mg/dL and HbA1c by 0.41% to 1% (12164,17488,17489,19756,95943,95945,95946). One meta-analysis of 92 patients shows that aloe vera is associated with a larger overall reduction of fasting blood glucose in those with a baseline fasting blood glucose level greater than or equal to 200 mg/dL (95945). Another meta-analysis of 206 patients shows that aloe vera increases high-density lipoprotein (HDL) levels and reduces triglyceride, total cholesterol, and low-density lipoprotein (LDL) levels when compared with placebo in adults with prediabetes and untreated diabetes (95943). These analyses include studies that used multiple forms of aloe vera, including gel powder, extract, raw crushed leaves, and fresh extracted juice, as well as multiple doses ranging from 100-1000 mg of powder and 15-150 mL of juice taken for durations ranging from 4-14 weeks. Significant heterogeneity between studies, small sample sizes, and wide variability in the form and dose of aloe used limit the validity of these findings and the ability to identify an effective dose (95943,95945,95946). Additionally, some research has shown no benefit. This may be due to the different forms and doses of aloe used. One clinical study shows that taking aloe gel as 15 mL twice daily or taking aloe juice 15 mL twice daily does not decrease glucose levels in patients with type 2 diabetes (17420). Other clinical research shows that taking a specific aloe gel complex (Aloe QDM complex, Univera Inc.) containing processed aloe gel 147 mg twice daily for 8 weeks does not affect glycemic indices when compared with placebo in patients with diabetes or prediabetes (90121).
Genital herpes. Topical aloe extract cream may improve healing of genital herpes lesions. Details: Clinical research in males with genital herpes shows that applying a cream containing aloe extract 0.5% three times daily, 5 days weekly, for up to 2 weeks increases healing rates when compared with aloe gel or placebo. The mean time to healing after application of the aloe extract was 5 days, compared with 12 days with placebo (12164,19745,19746).
Lichen planus. Rinsing the mouth with aloe-containing mouthwash or applying aloe gel to the mouth or vulva may reduce pain and improve lesion healing in patients with lichen planus. Details: Clinical research in patients with oral lichen planus shows that using 0.4 mL of mouthwash containing aloe gel 70% three times daily for 12 weeks or applying a gel containing aloe mucilage 70% twice daily for 8 weeks is up to 6 times more likely to reduce pain when compared with placebo (19762,19763,19764). However, these findings are questionable due to poor study design. Other clinical research in patients with oral lichen planus shows that using 2 tablespoons of aloe-containing mouthwash four times daily for a month, or applying aloe gel three times daily for 8 weeks, reduces pain and improves lesion healing at least as much as triamcinolone acetonide paste (0.1% in one study) (19765,90130). However, aloe gel may not be as beneficial as laser therapy. A clinical study in patients with lichen planus show that applying a gel containing aloe powder 500 mg to the affected site three times daily for 2 months is less effective for improving pain and lesion healing than receiving low-level laser therapy twice weekly for 2 months. However, no between-group differences were maintained at 7 months after treatment completion (108722). A network meta-analysis of 2 small clinical trials shows that applying aloe trails only purslane of the herbal agents studied with regard to clinical improvement as measured by the Thongprasom scale. However, aloe does not seem to improve complete clinical resolution, clinical scores, or pain (111640). In patients with vulval lichen planus, clinical research shows that topical application with aloe gel twice daily for 8 weeks increases the number of patients who experience clinical improvement of at least 50% when compared with placebo (19766).
Obesity. Oral aloe gel may modestly reduce body weight and fat mass in adults who are overweight or obese. Details: One clinical trial in overweight and obese adults with diabetes or prediabetes shows that taking a specific aloe gel complex (Aloe QDM complex, Univera Inc.) containing processed aloe gel 147 mg twice daily for 8 weeks reduces body weight by 0.6 kg and fat mass by 1 kg when compared with placebo (90121).
Oral submucous fibrosis. Topical aloe may reduce burning sensations in patients with oral submucous fibrosis, but it may not improve mouth opening, tongue protrusion, or cheek flexibility in these patients. Details: A meta-analysis of five small clinical studies in patients with oral submucous fibrosis shows that topical application of aloe gel for 3 months reduces burning sensation, possibly for up to two months after treatment, when compared with placebo or active control. A network meta-analysis also found that aloe is most effective in reducing burning sensation, ranked only after treatment with corticosteroids, hyaluronidase, and antioxidants (113514). However, aloe does not seem to improve mouth opening, tongue protrusion, or cheek flexibility (100256). One of the studies included in the analysis used a specific aloe gel (Sheetal lab Surat) 5 mg applied topically on each side of the buccal mucosa three times daily for 3 months (90131). All of the studies included in the analysis were conducted in India, so it is unclear if the results are generalizable to other geographic locations. Limited research has also evaluated the use of topical and oral aloe vera in combination. A small clinical study shows that consuming pure aloe vera juice (Hamant Sai, Sun Vision Company) 30 mL twice daily and applying pure aloe vera gel (Hamant Sai, Sun Vision Company) three times daily for 3 months improves cheek flexibility and tongue protrusion when compared with a treatment regimen consisting of intralesional injections of hydrocortisone acetate 25 mg and hyaluronidase 1500 IU weekly for 6 weeks and supplementation with Cap SM Fibro (Indoco Remedies) twice daily for 3 months. Both treatment regimens show an improvement in mouth opening and burning sensation when compared to baseline, with the aloe vera treatment producing a more rapid improvement in burning sensation (95944). It is not clear how this combination of oral and topical aloe vera compares with topical aloe vera alone.
Psoriasis. Topical aloe extract cream may reduce erythema and scaling and improve the resolution of psoriatic plaques in patients with psoriasis. Limited research suggests that topical aloe gel does not have the same effects. Details: Applying aloe extract 0.5% cream topically three times daily for 4 weeks significantly improves and increases the resolution of psoriatic plaques when compared with placebo (101,12096,12164). Aloe extract cream also seems to reduce desquamation, erythema, and infiltration (12096). Other preliminary clinical research shows that applying cream containing aloe mucilage 70% twice daily for 8 weeks improves psoriasis severity more effectively than triamcinolone 0.1% cream, although both treatments had similar effects on dermatology-specific quality of life (19741). Treatment with aloe gel does not seem to improve erythema, infiltration, and desquamation associated with psoriasis when compared with placebo (19748).
Radiation dermatitis. Although some individual research disagrees, topical aloe gel may prevent or delay dermatitis in patients undergoing radiation therapy. Details: A meta-analysis of 7 clinical trials in patients with various types of cancer shows that topical aloe does not reduce the incidence or severity of radiation dermatitis and does not reduce the incidence of erythema, pruritis, moist desquamation, or dry desquamation when compared with control (110325). However, the included studies are limited by a lack of blinding, questionable methodological quality, and a high risk of bias. In contrast, another meta-analysis of generally poor quality randomized controlled trials shows that topical pre-treatment application with aloe as gel, cream, lotion, or fresh plant reduces the risk of radiation dermatitis by 23%, especially mild to moderate radiation dermatitis, when compared with a control group not treated with aloe (110214). One U.S. study included in the analysis shows that applying aloe 98% gel twice daily starting within three days of radiation initiation does not reduce radiation dermatitis when compared with a placebo gel or no treatment (12163). Other research has focused on specific side effects. One clinical trial shows that applying aloe 98% gel three times daily throughout radiation treatment and after treatment does not seem to reduce symptoms of radiation dermatitis in patients being treated for breast cancer (12098). Some research shows that applying aloe 100% gel 6-8 times daily might prolong the time before radiation-related side effects occur, but only when the cumulative dose of radiation is high (>2,700 cGy) (12159). In addition, applying aloe-based gel once daily after radiation treatment is less effective than applying anionic phospholipid-based cream for reducing dryness, erythema, and peeling in children being treated for Hodgkin disease (19855). Aloe has also been evaluated in combination with other ingredients. A small cohort study in patients with head and neck cancer receiving radiation therapy shows that applying aloe 2% and radish 4% gel twice daily until ten days after the last radiotherapy session prevents radiation dermatitis as shown by fewer cases of radiation dermatitis in the 10^th, 30^th, and 35^th radiation sessions when compared with placebo. Furthermore, after the 35th session, the subjects prophylactically treated with the aloe and radish gel had milder grades of radiation dermatitis when compared with control (111662). A preliminary clinical study shows that applying a specific cream product (Radioskin 2, Herbalab di Perazza Massimiliano Company), which contains aloe, ginkgo extract, and metal esculetina, along with another specific cream product (Radioskin 1, Herbalab di Perazza Massimiliano Company), which contains alga atlantica and ethylbisiminomethylguaicolo manganese cloruro, may improve skin hydration and reduce skin toxicity associated with radiation therapy in patients with breast cancer (89727). These creams were applied topically 2-3 times daily at least 3 hours before and after radiation treatment, from 15 days prior to radiation until one month after completion.
Traumatic oral ulcers. Topical aloe gel may prevent oral ulcers after application of orthodontic appliances in adolescents and adults. Details: Clinical research in patients aged 12 years and older shows that applying a gel containing aloe 80% to the gums twice daily for one month after the cementation of orthodontic appliances prevents the development of mouth ulcers when compared with a chlorhexidine gel. Ulcers occurred in about 6% of patients using the aloe gel compared with 81% of those using the chlorhexidine gel. Bleeding and inflammation were also reduced (103305).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Alveolar osteitis. It is unclear if topical aloe or the aloe constituent acemannan is beneficial in patients with alveolar osteitis. Details: One small clinical trial in patients with alveolar osteitis shows that applying a patch containing the aloe constituent acemannan (SaliCept patch) to the tooth socket, once after curettage and irrigation and again 3 days later, reduces pain intensity and improves clinical symptoms when compared with curettage and irrigation alone (19754).
Amenorrhea. Although there has been interest in using oral aloe for amenorrhea, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Anal fissures. It is unclear if topical aloe is beneficial in patients with anal fissures. Details: One small clinical study in patients with chronic anal fissures shows that applying an aloe cream containing 0.5% powdered spray-dried inner aloe leaf juice (Zarban Phyto-Pharmaceutical Co) three times daily for at least 3 weeks, as an adjuvant to sitz baths three times daily, using a laxative, and eating a full fiber diet, improves pain, wound healing, and bleeding severity when compared with placebo (90129).
Asthma. Although there has been interest in using oral aloe for asthma, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Atopic dermatitis (eczema). Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients with atopic dermatitis shows that application of a specific combination cream (Olivederma, Kimi Daru Pharmaceutical Co.) containing aloe gel and virgin olive oil twice daily for 6 weeks improves disease severity and quality of life when compared with betamethasone cream (105020). It is unclear if this effect is due to aloe, olive oil, or the combination.
Breast engorgement. It is unclear if topical aloe improves lactation-associated breast pain. Details: Meta-analyses of 4-5 clinical trials in lactating patients show that use of topical aloe modestly reduces nipple/breast pain and irritation when compared with no treatment, routine care with topical breast milk or breast massage, or treatment with lanolin (110213). However, studies included in this analysis were not specific to breast engorgement.
Burning mouth syndrome. It is unclear if topical aloe is beneficial in patients with burning mouth syndrome. Details: One small clinical trial in patients with chronic burning mouth syndrome shows that applying 0.5 mL of aloe 70% gel to sore areas on the tongue three times daily prior to wearing a tongue protector for 12 weeks does not improve pain or symptoms when compared with placebo gel or using the tongue protector alone in patients with chronic burning mouth syndrome (90127). However, differences in baseline pain ratings between study groups limit the validity of these findings.
Cancer. Oral aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with lung cancer shows that, when administered with standard chemotherapy, three daily doses of 10 mL of a mixture consisting of fresh aloe leaves 300 grams plus honey 500 grams dissolved in 40 mL of alcohol 40% increases the rate of complete response, partial response, or disease control when compared with chemotherapy alone (19752).
Canker sores. Small clinical studies suggest that applying the aloe constituent acemannan to cancer sores may reduce ulcer size, but not pain. However, the effect of aloe is unclear. Details: Meta-analyses of clinical research show that topical aloe is no more effective than control interventions for reducing the size and pain of oral ulcers (110216). Control interventions have included carrier gel or triamcinolone acetonide 0.1% (19751,110216). However, a recent clinical trial shows that topical aloe gel (G.U.M Canker-X, Sunstar Americas, Schaumburg, USA) after meals and before bedtime for 5 days is more effective than amlexanox 5% paste and placebo for reducing pain and the size of canker sores in patients with recurrent symptoms (110215). Other small clinical trials have investigated the effects of fermented aloe or the aloe constituent acemannan. One small clinical trial in adults with recurrent canker sores shows that applying a fermented aloe gel to oral ulcers three times daily seems to accelerate healing time when compared with chitosan gel (104173). Another small clinical trial in patients with canker sores shows that using a wound dressing containing the aloe constituent acemannan (Carrisyn Gel Wound Dressing) shortens the average healing time of canker sores when compared with an oral analgesic (Orabase-Plain) (19750). Other clinical research shows that applying acemannan 0.5% in Carbopol 934P NF three times daily for 7 days reduces ulcer size, but not pain, when compared with Carbopol 934P NF alone in patients with canker sores (90123). However, applying triamcinolone acetonide 0.1% appears to be more effective in reducing pain and similarly effective in reducing ulcer size when compared with acemannan 0.5% (90123).
Common cold. Although there has been interest in using oral aloe for the common cold, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Dental plaque. Using aloe-containing toothpaste may reduce dental plaque in adults; however, it is unclear if this is more effective than fluoride-containing toothpaste. Rinsing with an aloe-containing mouthwash may reduce dental plaque in children. Details: One small clinical trial in adults shows that brushing teeth with a dentifrice containing aloe gel (Forever Bright, Forever Living Products) three times daily for 30 days does not reduce the occurrence of plaque better than a fluoridated dentifrice (Sorriso Dentes Brancos, Kolynos do Brasil), although both treatments seem to show improvement when compared to baseline (19755). Another small clinical study in adults with gingivitis shows that using toothpaste containing aloe daily for 24 weeks reduces plaque more effectively than placebo or triclosan-containing toothpaste (19760). In children aged 8-14 years with mild plaque, using a mouth wash containing aloe vera 7% twice daily for 4 weeks reduced plaque by a large amount when compared with placebo. In addition, it was as effective as chlorhexidine 0.2% (103306).
Depression. Although there has been interest in using oral aloe for depression, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Diabetic foot ulcers. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients with a stage 1 or 2 diabetic foot ulcer who are receiving oral antibiotics shows that applying a topical product containing aloe and great plantain twice daily for 4 weeks reduces ulcer surface area and time to healing, but not ulcer depth, when compared with antibiotics alone (97323). The effect of applying aloe gel alone without concomitant oral antibiotic therapy is unknown.
Diaper rash. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial shows that applying a cream containing aloe gel and olive oil three times daily for 5-10 days reduces diaper rash severity in children less than 3 years of age when compared to baseline; however, it does not seem to be as effective as calendula ointment (19779). The validity of this finding is limited by the lack of a placebo group.
Dry mouth. It is unclear if rinsing with an aloe-containing mouthwash is beneficial for dry mouth. Details: In patients with dry mouth related to type 2 diabetes, clinical research shows that an aloe vera 50% mouthwash, as 20 mL swished and spit three times daily for 14 days, modestly reduces symptoms of dry mouth when compared with rinsing with a saline control mouthwash (106068). The validity of this study is limited due to unclear reporting.
Dry skin. Topical aloe or oral aloe sterols may improve some measures of dry skin. However, findings are mixed due to the use of varied formulations and doses. Details: One small clinical trial shows that applying a cream containing freeze-dried aloe extract 0.1% to 0.5% to the skin for 2 weeks increases the amount of water in the stratum corneum, but does not reduce transepidermal water loss, when compared with placebo (19758). Another small clinical study in females with occupational dry skin shows that wearing gloves coated in aloe 8 hours daily for 30 days improves symptoms of dry skin when compared with no treatment (19759). However, it is not clear if the benefits resulted from applying aloe or wearing gloves. One small clinical trial in healthy females shows that consumption of a yogurt containing 500 mg of aloe vera gel powder (0.4 mg of aloe sterol) daily for 12 weeks increases skin hydration, skin elasticity, and collagen content of the dermis while reducing markers of skin fatigue and transepidermal water loss when compared with placebo (95942). However, another study in healthy females shows that taking aloe sterol-enriched aloe extract 0.5 grams daily for 12 weeks does not improve skin hydration when compared with placebo, although redness, itching, collagen content, and transepidermal water loss were improved (101577).
Epilepsy. Although there has been interest in using oral aloe for epilepsy, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Frostbite. Although there has been interest in using topical aloe for frostbite, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Gingivitis. Using aloe-containing toothpaste may reduce gingivitis in adults, but it does not seem to be more effective than fluoride-containing toothpaste. Rinsing with an aloe-containing mouthwash may reduce gingivitis in children. Details: One small clinical trial in adults shows that brushing teeth with a dentifrice containing aloe gel (Forever Bright, Forever Living Products) three times daily for 30 days does not reduce the occurrence of gingivitis more effectively than a fluoridated dentifrice (Sorriso Dentes Brancos, Kolynos do Brasil), although both treatments seem to show improvement when compared to baseline (19755). Another small clinical study in adults with gingivitis shows that using aloe-containing toothpaste daily for 24 weeks reduces gingivitis more effectively than placebo, but not more than triclosan-containing toothpaste (19760). In children aged 8-14 years with mild gingivitis, using a mouthwash containing aloe vera 7% twice daily for 4 weeks reduced gingivitis by a large amount when compared with placebo. In addition, it was as effective as chlorhexidine 0.2% (103306).
Heart failure. It is unclear if oral aloe is beneficial in patients with systolic heart failure. Details: A very small clinical study in adults with moderate to moderately severe chronic systolic heart failure shows that taking aloe vera gel capsules 150 mg twice daily for 8 weeks in addition to standard treatment decreases New York Heart Association (NYHA) functional class, improves Minnesota Living with Heart Failure Questionnaire (MLHFQ) total, physical, emotional, and social scores, and enhances sleep quality but does not reduce the severity of obstructive sleep apnea scores or improve six-minute walk test distance when compared with placebo (111663). The study may have been inadequately powered to detect a difference between groups. Additionally, the validity of these effects may be limited by the small sample size.
Hematopoietic stem cell transplant (HSCT). Oral and topical aloe have only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients undergoing hematopoietic stem cell transplantation shows that treatment with colostrum and aloe orally (Remargin Colostrum Gastro-Gel, Solimè srl, Cavriago, Reggio Emilia, Italy) and as a mouthwash (Remargin Colostrum OS, Solimè srl, Cavriago, Reggio Emilia, Italy) modestly reduces the risk and duration of severe oral mucositis and febrile neutropenia when compared with historical values. There was no effect on the duration of neutropenia, the length of hospital stay, pain, or duration of medications. All patients were also given standard care. The mouthwash was used after each oral hygiene, and the oral treatment was 3 to 5 times daily depending on symptoms (110211).
Hepatitis. It is unclear if oral aloe is beneficial in patients with hepatitis. Details: One small clinical trial in patients with liver fibrosis primarily caused by hepatitis B or hepatitis C shows that taking a high molecular weight fraction of aloe 0.05 grams three times daily for 12 weeks reduces fibrosis, attenuates liver enzyme activity, and decreases hepatic glutathione content when compared with placebo (19780).
HIV/AIDS. Small clinical studies suggest that oral aloe or the aloe constituent acemannan may not improve CD4 counts or viral load in patients with HIV. Details: One small clinical trial in patients with HIV shows that taking the aloe constituent, acemannan, 400 mg four times daily does not significantly improve CD4 counts, ratio of CD4 to CD8, or viral load when compared with placebo (19851). Another small clinical study in patients with HIV shows that taking aloe gruel 30-40 mL daily does not improve CD4 counts when compared with those treated with antiretroviral therapy, although both groups show similar increases in weight compared to baseline (19852).
Hyperlipidemia. Although there has been interest in using oral aloe for hyperlipidemia, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Hypertrophic scars. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients undergoing median sternotomy shows that applying a silicone gel containing aloe extract and other herbal extracts (Bangkok Botanica) to postoperative hypertrophic scars for 6 months reduces the height of the scar and improves pliability by a moderate amount when compared with a silicone placebo gel. There was no effect on pigmentation or vascularity (102793). It is unknown whether any benefit is related to aloe, other ingredients, or their combination.
Influenza. Oral aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in healthy adults shows that taking a combination supplement containing aloe vera gel, rosemary, and poria mushrooms twice daily 28 days before administering the influenza vaccine and 28 days after vaccination does not improve immunologic markers or reduce symptom severity, symptom duration, frequency of upper respiratory tract infection symptoms, or the use of cold and flu medications when compared with placebo (111921).
Irritable bowel syndrome (IBS). Small clinical studies suggest that oral aloe extract or juice may not improve symptoms in patients with IBS. Details: Most research suggests that aloe is not effective for improving symptoms of IBS; however, the available evidence is of low-quality, with some studies having high dropout rates or inadequate power to detect significant differences. Two clinical trials show that taking a specific aloe extract (AVH200, Calmino Group AB) 250-500 mg twice daily for 4 weeks does not improve IBS-related symptoms or response rates when compared with placebo (101579,104169), although one of these studies did find a trend toward a higher response rate, defined as a 50% or greater improvement in symptom scores, with aloe over placebo (104169). Also, a pooled analysis of these two studies shows that taking this specific product improves IBS-related pain severity and frequency in patients with diarrhea-prominent IBS (IBS-D) when compared with placebo, but does not seem to improve stool consistency or frequency (108718). Clinical trials evaluating aloe juice 50 mL four times daily for 1 month or 60 mL twice daily for 5 months show no significant improvement in quality of life scores or IBS symptoms when compared with placebo (104170,104171), although one study did find a trend toward improved response in patients with IBS-D (104171). Despite a lack of significant findings in the individual studies, a pooled analysis of the two smallest studies above (104169,104171) shows that aloe extract or juice, taken for 4 weeks, may increase the rate of symptom response by almost 70% when compared with placebo (103307).
Nipple Fissures. It is unclear if application of an aloe poultice improves nipple-related complications of breastfeeding, such as nipple fissures. Details: A clinical study in females who have just given birth and are breastfeeding for the first time shows that applying a poultice containing aloe gel to the nipples after breastfeeding six times daily for 5 days improves nipple eschar when compared with no treatment. Although there were modest improvements in other outcomes, such as redness, fissures, and epidermolysis, these differences were not significant (108721). Participants were instructed to clean with purified water before the next breastfeeding session.
Multiple sclerosis (MS). Although there has been interest in using oral aloe for MS, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Oral mucositis. Small clinical studies suggest that oral aloe juice or application of aloe solution inside the mouth may prevent oral mucositis in patients receiving chemotherapy or radiation. Details: Some clinical research shows that drinking 15 mL of juice containing aloe 80% three times daily during radiation therapy decreases the risk of developing moderate or severe mucositis by approximately 39% when compared with placebo (19767,19964). In addition, in children aged 3-6 years undergoing chemotherapy for leukemia, application of a solution containing aloe 70% twice daily inside the mouth, starting three days before chemotherapy, reduces the severity of oral mucositis and delays its onset by 2 weeks when compared with sodium bicarbonate 5% (103304). Other clinical research in adults with head and neck cancer shows that rinsing and then swallowing 20 mL of a solution containing aloe juice 94.5% four times daily throughout the course of radiation therapy does not prevent mucositis when compared with placebo (19963). However, this study was not adequately powered to detect significant differences between study groups. Aloe has also been evaluated in combination with other ingredients for the treatment of oral mucositis. Preliminary clinical research in patients undergoing hematopoietic stem cell transplantation shows that treatment with colostrum and aloe orally (Remargin Colostrum Gastro-Gel, Solimè srl, Cavriago, Reggio Emilia, Italy) and as a mouthwash (Remargin Colostrum OS, Solimè srl, Cavriago, Reggio Emilia, Italy) modestly reduces the risk and duration of severe oral mucositis when compared with historical values. There was no effect on overall risk or time of onset of mucositis. All patients were also given standard care. The mouthwash was used after each oral hygiene, and the oral treatment was 3 to 5 times daily depending on symptoms (110211). Another small clinical study in adults with head and neck cancer receiving radiotherapy shows that rinsing with 5 mL of a mouthwash containing aloe, German chamomile, peppermint oil, and honey 3 times daily for 60 seconds for 6 weeks starting on the first day of radiotherapy reduces oral mucositis incidence, severity, and pain when compared with chlorhexidine and placebo (111291). It is unclear if these findings are due to aloe, other ingredients, or the combination.
Osteoarthritis. Although there has been interest in using oral and topical aloe for osteoarthritis, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Peptic ulcers. Although there has been interest in using oral aloe for peptic ulcers, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Periodontitis. It is unclear if application of aloe inside the mouth is beneficial for chronic periodontitis. Details: A meta-analysis of small clinical studies in patients with chronic periodontitis shows that using various aloe-containing gels, mouthwashes, and toothpastes improves plaque index when compared with placebo or other treatments (i.e., chlorhexidine rinse, metformin, and tea tree oil). The effect of these aloe products on gingival index could not be determined (108719). The validity of this finding is limited by the variety of aloe formulations and comparators used in the included studies.
Pressure ulcers. It is unclear if topical aloe is beneficial for the prevention or treatment of pressure ulcers. Details: One small clinical study shows that applying a gel containing the aloe constituent acemannan to pressure ulcers daily for 10 weeks does not reduce the time to healing when compared with management with moist saline gauze (12160,19853). Other clinical research shows that cleansing wounds with a saline spray containing aloe, silver chloride, and decyl glucoside for 2 weeks improves pressure ulcer healing when compared with isotonic saline spray (19854). It is unclear if this improvement is due to aloe, other ingredients, or the combination in the spray. Aloe has also been evaluated for the prevention of pressure ulcers. A small clinical study in hospitalized patients in an orthopedic ward shows that applying aloe vera gel to the hips, sacrum, and heels twice daily for 10 days reduces pressure ulcer occurrence to 3 of 39 patients, compared to 12 of 38 patients of those receiving placebo (98816). However, methodological limitations with this study, including differences in how the gels were applied, limit the reliability of these results. A clinical study in hospitalized patients receiving intensive care has evaluated either aloe gel 94%, olive oil 100%, or a compounded product containing aloe vera and olive oil in a 3:2 ratio, applied to pressure areas as 10-15 mL every 8 hours. At the end of 30 days, pressure ulcers occurred in 17% of patients receiving the combination product, 20% receiving olive oil, 33% receiving aloe gel, and 37% receiving standard care, suggesting that any benefit may be due to olive oil (108723).
Radiation proctopathy. It is unclear if topical aloe is beneficial for the prevention or treatment of radiation proctopathy. Details: One very small clinical study in females with radiation proctopathy shows that applying 1 gram of an ointment containing aloe vera 3% rectally twice daily in conjunction with taking sulfasalazine 500 mg four times daily for 4 weeks modestly reduces diarrhea, fecal urgency, radiation toxicity, and clinical symptoms when compared with sulfasalazine alone (95941). This same product, applied twice daily for 6 weeks starting on the first day of radiotherapy, has also been evaluated for the prevention of radiation proctopathy. One small clinical study in patients with pelvic cancer shows that applying this ointment prevents proctopathy-related diarrhea, rectal bleeding, and fecal urgency when compared with placebo. Proctopathy-related symptoms occurred in 5% of patients using aloe, compared with 65% of those using placebo. However, there was no difference in rectal pain, constipation, or symptoms of cystitis between groups (101578). A very small clinical study in patients with colorectal cancer shows that applying this ointment prevents proctopathy-related diarrhea and reduces proctopathy severity, but does not improve rectal bleeding, rectal pain, fecal urgency, or symptoms of cystitis, when compared with placebo (108717). Reasons for discrepancies are unclear but might relate to differences in cancer diagnosis and radiation regimens.
Scabies. It is unclear if topical aloe is beneficial in patients with scabies. Details: One small open-label clinical study in children and adults with scabies shows that application of crude aloe gel for 3 consecutive days, repeated again after one week, may reduce itching and lesions similar to benzyl benzoate lotion in patients with scabies when compared to baseline (19769). The validity of this finding is limited by the lack of a placebo group.
Seborrheic dermatitis. It is unclear if topical aloe is beneficial in patients with seborrheic dermatitis. Details: One small clinical study in adults with seborrheic dermatitis shows that applying aloe 30% emulsion twice daily for 4-6 weeks reduces scaling, itching, and the number of sites involved, but not erythema, when compared with placebo (19749).
Stretch marks (striae gravidarum). It is unclear if topical aloe is effective for the prevention or treatment of stretch marks. Details: One small clinical trial in nulliparous patients shows that topical application of a cream containing aloe twice daily, starting at gestational week 16-18, reduces erythema and itching related to abdominal stretch marks, but does not seem to decrease the number of stretch marks, when compared with a base cream (97322). Aloe gel has also been evaluated in combination with fractional carbon dioxide (CO2) laser treatments. A small clinical trial shows that applying a gel containing aloe 87.4% twice daily for up to one month after each of three CO2 laser treatments improves the texture of the skin for up to 6 months after the last laser treatment when compared to baseline. This was as effective as topical recombinant human epidermal growth factor (rhEGF) and CO2 laser treatments. However, when specific sites were examined, only the texture of stretch marks on the buttocks were improved, and these improvements were less than those seen with rhEGF (101580). The effect of aloe for the prevention of stretch marks is unknown.
Sunburn. Although there has been interest in using topical aloe for sunburn, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Tungiasis. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study shows that applying a product containing coconut oil, jojoba oil, and aloe leaf extract (Zanzarin, Engelhard Arzneimittel GmbH & Co. KG) to the feet twice daily for one-week intervals seems to reduce the number of embedded sandfleas in individuals with tungiasis when compared with a control group (19778). It is not clear if this effect is due to aloe, the other ingredients, or the combination.
Ulcerative colitis. It is unclear if oral aloe gel is beneficial in patients with ulcerative colitis. Details: One small clinical trial in patients with mild to moderate ulcerative colitis shows that taking aloe gel for 4 weeks, starting at 25-50 mL twice daily for the first 3 days and increasing to 100 mL twice daily thereafter, reduces symptoms when compared with placebo (11984).
Vaginitis. It is unclear if topical aloe is beneficial for vaginitis. Details: One small clinical trial in postmenopausal patients with atrophic vaginitis shows that applying 5 mg of a vaginal cream containing aloe gel 2% nightly for 2 weeks, then 3 nights per week for 4 weeks, reduces vaginal dryness, burning, and pain during intercourse and improves measures of vaginal health and maturity when compared to baseline. These effects were similar to those seen with estrogen vaginal cream (104175).
Varicose veins. Although there has been interest in using oral and topical aloe for varicose veins, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Wound healing. There is conflicting evidence about the effectiveness of topical aloe products for improving wound healing. These conflicting findings may be due to differences in study designs, products used, and application practices. Details: One small clinical study shows that applying aloe gel to a caesarean wound after surgery, followed by a dry gauze, improves wound healing over the first 24 hours when compared with the dry gauze alone (90128). However, other clinical research in a small number of patients undergoing gynecologic surgery or cesarean section shows that applying an aloe gel extract (Carrington Dermal Wound Gel) to surgical wounds may actually delay wound healing (11982). Another small clinical trial shows that applying a formulation of aloe gel 0.5% cream (Zarband, Phytopharmaceutical Co.) to hemorrhoidectomy wounds three times daily for 4 weeks improves healing rates and pain relief scores and decreases intake of narcotic analgesics when compared with placebo (17418). However, another clinical trial in patients with biopsy wounds shows that application of a hydrogel containing the aloe constituent, acemannan (Carrasyn, Carrington hydrogel), does not improve wound epithelialization, wound infections, or pain when compared with conventional therapy (19856). Additionally, there is contradictory evidence about the effectiveness of aloe for improving skin graft donor site healing. One small clinical study shows that applying aloe gel 87.4% daily to split-thickness skin graft donor sites reduces time to complete healing by about 2 days when compared with placebo (97320). However, another small clinical study shows that applying aloe cream three times daily to split-thickness skin graft donor sites does not improve healing time when compared with placebo (97321).
Wrinkled skin. Although there has been interest in using topical aloe for wrinkled skin, there is insufficient reliable information about the clinical effects of aloe for this purpose. More evidence is needed to rate aloe for these uses.

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LARCH ARABINOGALACTAN (Arabinogalactan Heartwood)

INSUFFICIENT RELIABLE EVIDENCE to RATE

Common cold. Preliminary clinical research shows that taking a specific larch arabinogalactan extract (ResistAid, Lonza Ltd.) 4.5 grams daily for 12 weeks does not significantly decrease the number, intensity, or symptoms of common colds when compared with placebo in patients who frequently suffer from colds. However, larch arabinogalactan appears to increase the percentage of patients who experience no cold episodes. About 42% of patients receiving larch arabinogalactan extract had no cold episodes, compared to only 28% of patients receiving placebo (93104).
Hyperlipidemia. Preliminary clinical research shows that taking larch arabinogalactan 8.4 grams daily for 6 months, or 15-30 grams daily for 6 weeks, does not significantly lower total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, apolipoprotein B (apo B), apolipoprotein A-1, body weight, blood pressure, or glucose levels in healthy people (15617,15620). It is not known if larch arabinogalactan lowers lipid levels in patients with hyperlipidemia. More evidence is needed to rate larch arabinogalactan for these uses.

OLIVE (Olive leaf extract)

INSUFFICIENT RELIABLE EVIDENCE to RATE

Dyspepsia. Oral olive leaf extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in healthy adults shows that taking a specific combination product containing olive leaf extract 24% and prickly pear cactus 33% (Mucosave, Bionap S.R.L.) 400 mg daily for 8 weeks seems to improve dyspepsia and other gastrointestinal symptoms when compared with placebo (105904). It is unclear if this benefit would occur in patients with clinically diagnosed dyspepsia.
Exercise-induced respiratory infections. It is unclear if oral olive leaf extract is beneficial for reducing respiratory infections from exercise. Details: A small clinical study in high school athletes shows that taking one tablet of olive leaf extract providing eleuropein 100 mg daily for 2 months during training season does not reduce the incidence of the common cold when compared with placebo. While it may reduce the number of sick days by 28%, a sub-group analysis suggests that this reduction is only evident in female athletes (101860).
Gastroesophageal reflux disease (GERD). Although there is interest in using oral olive leaf for GERD, there is insufficient reliable information about the clinical effects of olive for this condition.
Herpes zoster (shingles). Although there is interest in using oral olive leaf for shingles, there is insufficient reliable information about the clinical effects of olive for this condition.
Influenza. Although there is interest in using oral olive leaf for influenza, there is insufficient reliable information about the clinical effects of olive for this condition.
Metabolic syndrome. It is unclear if oral olive leaf extract is beneficial for improving body composition and cardiovascular risk factors in patients with metabolic syndrome. Details: A small clinical trial in overweight, middle-aged males at risk for metabolic syndrome shows that taking four capsules of olive leaf extract providing oleuropein 51.1 mg and hydroxytyrosol 9.7 mg daily for 12 weeks improves insulin sensitivity by 15% when compared with placebo. However, body composition, blood pressure, cholesterol levels, and other cardiovascular risk factors were not improved (92245).
Osteoarthritis. It is unclear if oral olive fruit or leaf extract is beneficial for improving osteoarthritis. Details: Preliminary clinical research shows that taking a freeze-dried aqueous extract of olive fruit 400 mg daily for 8 weeks decreases pain and increases mobility in people with osteoarthritis (14844). Other preliminary clinical research in adults with knee osteoarthritis shows that taking olive leaf extract 50.1 mg daily for 4 weeks improves overall pain measurements by 14%, compared to only 4% in the placebo group. However, many individual measurements of pain are not improved (92252).
Osteoporosis. It is unclear if oral olive leaf extract is beneficial for osteoporosis. Details: Clinical research shows that taking olive leaf extract (Bonolive, BioActor BV) 250 mg daily for 12 months, along with elemental calcium 400 mg daily, increases osteocalcin levels by about 32% when compared to baseline; this increase was significant when compared to those taking calcium 400 mg plus placebo, who showed a 6% decrease in osteocalcin levels. However, taking olive leaf extract does not significantly increase bone mineral density of the lumbar spine or femur neck when compared with placebo (92247).
Rheumatoid arthritis (RA). It is unclear if oral olive fruit extract is beneficial for improving RA symptoms. Details: Preliminary clinical research in adults with RA shows that taking an aqueous freeze-dried extract of olive fruit 400 mg daily for 8 weeks does not improve symptoms when compared with control (14844). More evidence is needed to rate the effectiveness of olive for these uses.

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ZINC

EFFECTIVE

Zinc deficiency. Orally or intravenously, zinc is effective for treating and preventing zinc deficiency. Details: Taking zinc orally or intravenously prevents and treats zinc deficiency (2619). However, routine zinc supplementation is not recommended (403). Zinc deficiency requiring supplementation may occur in patients with severe diarrhea, malabsorption syndromes, liver cirrhosis, and alcoholism; after major surgery, renal failure, and dialysis; or during long-term administration of total parenteral nutrition (3900,24321). Zinc supplementation (136 mg of elemental zinc per day) in patients with cirrhosis and zinc deficiency seems to improve liver function and glucose tolerance, possibly by increasing insulin-like growth factor (8624,87520).

LIKELY EFFECTIVE

Diarrhea. Oral zinc reduces duration and severity of acute diarrhea in malnourished children. Doses of 5-20 mg seem to be effective, while 5-10 mg daily is less likely to cause vomiting. Details: Most research, including meta-analyses and over 30 clinical trials, show that taking zinc orally reduces the duration and severity of acute and persistent diarrhea in malnourished or zinc-deficient children, but not in well-nourished children (87236,96074). Most studies have been conducted in Bangladesh and India, so it is unclear if these findings are generalizable to other geographic locations. The most comprehensive meta-analysis of clinical studies in children older than 6 months shows that zinc supplementation reduces the duration of acute diarrhea by about 11 hours and the duration of persistent diarrhea by about 16 hours when compared with placebo. However, zinc does not seem to reduce the duration of acute diarrhea in children younger than 6 months. Zinc supplementation seems to have the greatest benefit in children with clear malnutrition and diarrhea. In these children, zinc reduces diarrhea duration by about 26 hours and reduces the risk of diarrhea persisting through days 3, 5, and 7 by 18% to 24% when compared with placebo. There was no clear benefit of using zinc in a specific dose or salt form. The most common dose of zinc was 20 mg daily and salt forms included zinc sulfate, gluconate, and acetate (96074). Also, a large clinical trial in children with acute diarrhea shows that taking zinc 5 or 10 mg daily for 14 days is non-inferior to taking 20 mg. Furthermore, zinc 5 or 10 mg results in a respective 29% and 19% lower risk of vomiting within the first 30 minutes when compared with zinc 20 mg (104045). It's unclear whether zinc supplementation reduces mortality in children with diarrhea. A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of mortality from diarrhea by 15% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). However, many studies were conducted in hospitals where rates of mortality are low and were not adequately powered to determine whether zinc has an effect on mortality in children with acute diarrhea (87210,96074,106239).
Wilson disease. Taking zinc orally improves symptoms of this condition. Details: Zinc acetate (Galzin) is an FDA-approved orphan drug for treating this condition. Zinc blocks copper absorption and increases copper elimination in the stool of people with Wilson disease (2692,2693,87327). Small clinical studies suggest that taking zinc after 8 weeks of treatment with tetrathiomolybdate alone can improve Kayser-Fleischer rings, urine copper levels, and neurological symptoms for up to 6 years post-treatment (63588,87491).

POSSIBLY EFFECTIVE

Acne. Orally, zinc might help to reduce symptoms of acne. However, it's unclear how oral zinc compares to conventional acne treatments. Topical zinc doesn't seem to be beneficial if used alone. Details: Observational research has found that people with acne seem to have lower zinc levels in the serum and skin (104056). A meta-analysis of small, low quality clinical trials suggests that taking zinc sulfate or zinc gluconate 137-300 mg 2-3 times daily by mouth can modestly improve acne when compared with placebo (104056). However, not all individual trials show benefit (87002,104056). So far, it is not clear how oral zinc compares to other treatments. Trials comparing zinc sulfate with various tetracyclines have yielded conflicting results (6505,6506,86946,106233). One large open-label clinical trial shows that taking zinc sulfate 200 mg twice daily for 12 weeks is at least as effective as lymecycline 300 mg daily for reducing acne severity. Quality of life related to acne was modestly improved in the patients using zinc sulfate (106233). However, in another clinical trial, a 3-month treatment of oral zinc gluconate 30 mg daily reduced the number of acne lesions from baseline, but was not as effective as minocycline (86946). When applied topically, clinical research shows that zinc does not help treat acne when compared with placebo (87297,104056). However, when used in combination with erythromycin, topical zinc seems to result in improvement (819,820,2687,2688).
Acrodermatitis enteropathica. Oral zinc seems to improve symptoms of this rare genetic disorder. Details: Multiple case reports have found that taking oral zinc seems to help improve symptoms of acrodermatitis enteropathica, a rare disorder (821,2689,2690,2691). One case report in a female with necrolytic acral erythema and hepatitis C suggests that adding oral zinc sulfate 225 mg twice daily to interferon alfa-2b for 6 months contributed to resolving all lesions. Necrolytic acral erythema is categorized in the family of necrolytic erythemas that includes acrodermatitis enteropathica (6192).
Age-related macular degeneration (AMD). Oral zinc, especially in combination with antioxidant vitamins, seems to slow the progression of AMD. Details: Clinical research shows that taking elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily reduces the odds of progression to advanced AMD by 28%. In patients with more severe AMD, this combination reduced the odds of progression to advanced AMD by 34%. This combination also reduced the odds of visual acuity loss by 27% in patients with severe AMD (7303,11326). However, there is contradictory evidence about the effects of zinc plus antioxidants on visual acuity loss or the progression to advanced AMD in low-risk patients with AMD (6583,6584,7303). Some clinical evidence shows that, when taken without antioxidant vitamins, zinc supplementation does not slow the progression of existing AMD (6580,90069). However, a subgroup analysis of results from a large clinical trial that included patients with intermediate or advanced AMD suggests that the effect of zinc on AMD progression might vary depending on a patient's genetic predisposition. Complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) are two genes for which specific variations (i.e., risk alleles) have been associated with an increased risk of AMD. Results from the retrospective subgroup analysis suggest that zinc supplementation may DECREASE the progression of AMD in patients with ARMS2 risk alleles and INCREASE the progression of AMD in patients with CFH risk alleles (90193). However, some experts question the results from this analysis due to the retrospective nature of the study (93045). Another retrospective analysis of similar data found that only zinc plus antioxidants, but not zinc alone, was beneficial for slowing the progression of AMD, regardless of the patient's genotype (93046). Consequently, the American Academy of Ophthalmology does not currently recommend routine genetic screening to determine which patients would benefit from zinc, antioxidants, or the combination. Instead, patients with intermediate or advanced AMD are recommended to take an antioxidant and zinc supplement similar to those used in the Age-Related Eye Disease Study (AREDS) and the Age-Related Eye Disease Study 2 (AREDS2) (93047). Large scale population studies suggest that increasing dietary intake of zinc might reduce the risk of developing AMD (6579,14257).
Child growth. Oral zinc seems to increase growth when taken by children and improve infant growth in the first year of life when taken by pregnant adults. Details: A meta-analysis of 8 clinical studies in healthy children over 2 years old shows that taking supplemental zinc 5-15 mg daily for 6-56 weeks modestly increases height and weight when compared with placebo. This analysis also shows that taking zinc may improve height for age, but not weight for age when compared with placebo (112474). Most of these studies were conducted in developing countries; results may not apply elsewhere. Another clinical study in pregnant adults in Peru shows that taking zinc 15 mg daily in addition to iron and folic acid, starting during the first or second trimester and continuing up to one month after delivery, modestly improves growth measures of infants at one year when compared with taking iron and folic acid alone. Improved growth measures include body weight, calf and chest circumference, and calf muscle area (87130).
Common cold. Oral zinc seems to help treat cold symptoms in adults. However, it is unclear if zinc is beneficial for common cold prevention. Details: Using zinc oral lozenges seems to be beneficial in helping TREAT the common cold in adults. The majority of clinical trials and analyses of clinical research show a significant decrease in the duration of symptoms of the common cold when adults take zinc gluconate or zinc acetate lozenges providing 9-24 mg of elemental zinc per dose. It is recommended that lozenges be taken every 2 hours while awake, starting within 48 hours of symptom onset for a total daily dose of at least 75 mg in order to attain a mean cold duration reduction of 3 days (333,334,335,337,6703,6705,87501,92212,106902). However, not all studies have been positive (333,338,339,6522,6700,87512). The reasons for these different findings are not clear, but might be due to differences in zinc formulations and doses and study methodologies. In some cases, flavoring agents such as citric acid, mannitol, and sorbitol might chelate zinc and decrease zinc ionization. Since ionization is thought to be necessary for zinc activity, a decrease in zinc ionization could decrease effectiveness (300,340,6522). Some of the positive studies have also been criticized for inadequately blinding the unpleasant, distinctive taste of zinc (6522,6706). Allergy and smoking status do not appear to impact the efficacy of zinc acetate lozenges (92212). Overall, zinc products may be beneficial for modestly reducing the duration of symptoms of the common cold in adults, but adverse effects such as bad taste and nausea may limit their usefulness (18216). There is conflicting evidence for the use of oral zinc products to PREVENT colds. Some clinical research suggests that taking zinc prophylactically does not prevent the common cold in adults (10780,10784) or children (341). However, other clinical research suggests that administering zinc gluconate lozenges can reduce the incidence of colds in children and adolescents (10803,86972). In a meta-analysis of 28 randomized controlled trials with a total of 5446 participants, oral zinc prevented 5 viral upper respiratory tract infections per 100 person months of zinc use when compared with placebo, with a number needed to treat (NNT) of 20 (106902). Intranasal zinc is not recommended for the prevention or treatment of the common cold due to the risk for anosmia. See the Adverse Effects section for more information. Some research shows that zinc nasal spray (as a sulfate, gluconate emulsion, or gluconium gel) reduces the severity and duration of cold symptoms; however, other research has found no effect (6471,8628,8629,10247,87035). Zinc nasal spray does not seem to prevent experimentally-induced colds (8628).
Coronavirus disease 2019 (COVID-19). While oral zinc does not seem to speed recovery from COVID-19 in non-hospitalized patients, an analysis of a small number of studies suggests that oral or intravenous zinc might reduce the risk of death in hospitalized patients with COVID-19. Details: A small observational study in patients with COVID-19 has found that lower serum zinc levels are associated with worse clinical outcomes, such as admission to the intensive care unit (ICU) and death, when compared with higher zinc levels (105681). Another small observational study has found that 96% of patients with confirmed COVID-19 were zinc-deficient based on plasma levels of zinc, and that these patients had lower plasma zinc levels than a group of individuals without COVID-19. However, plasma zinc concentrations were only weakly correlated with length of hospital stay and there was no correlation with morbidity or mortality (106236). One clinical study in adult outpatients with COVID-19 shows that taking zinc gluconate 50 mg daily at bedtime, alone or with vitamin C (ascorbic acid) 8000 mg daily, for 10 days does not reduce symptom severity when compared with standard care (104450). This study was terminated prior to complete enrollment due to a lack of effect with zinc and/or vitamin C supplementation. Limitations of this study include a lack of placebo control and blinding. Zinc supplementation also does not appear to enhance the clinical efficacy of hydroxychloroquine in patients with confirmed COVID-19 infection. Taking zinc sulfate 220 mg twice daily during a 6-day course of hydroxychloroquine does not improve the clinical recovery rate, reduce the mortality rate, or reduce the need for mechanical ventilation when compared with hydroxychloroquine alone (104818). Other research has evaluated zinc in hospitalized patients. Multiple meta-analyses of small and low-quality clinical studies, including randomized controlled trials and retrospective studies, involving hospitalized patients with COVID-19 shows that supplementation with oral or intravenous zinc is associated with a 29% to 43% reduction in the odds of in-hospital mortality when compared with control (109451,110631). However, in one meta-analysis, the odds of 30-day mortality were not different between groups (110631). These meta-analyses did not elevate the most effective form, dose, frequency, or duration of zinc supplementation (109451,110631). Additionally, a retrospective study in adults admitted to the ICU with COVID-19 has found that those who received oral zinc sulfate, 220 mg daily for a median of 11 days, had a lower 30-day mortality rate when compared with those who did not receive zinc. However, there was no difference in hospital length of stay or in-hospital mortality (106903).
Depression. Oral zinc seems to be beneficial when used in combination with antidepressant treatments. Details: Population research has found that higher zinc levels and higher dietary intake of zinc are associated with a 28% lower incidence of depression (90227,97139,104057). Oral zinc seems to be beneficial as an adjunct therapy in depression. A meta-analysis of small, low-quality studies in patients with major depression shows that taking zinc in addition to antidepressant therapy is associated with modestly improved depression symptoms when compared with antidepressant therapy alone (104044). Clinical studies used zinc doses of 7-25 mg daily for up to 12 weeks (86985,90221,104044). One small clinical study also shows that adding zinc to imipramine therapy might improve depression that was previously resistant to antidepressant treatment (87158). One clinical guideline also provisionally recommends use of zinc 25 mg elemental orally daily to treat patients with depression based on low-quality evidence. This guideline recommends use of chelated or picolinate zinc products over other forms of zinc (110318).
Diabetes. Oral zinc might modestly improve glycemic control in some patients. Details: A meta-analysis of 12 clinical studies in patients with diabetes shows that taking zinc supplements reduces fasting blood glucose by up to 20 mg/dL and glycated hemoglobin (HbA1c) by 0.35% when compared with control. However, when only high quality studies were included, the reduction in fasting blood glucose dropped to 12 mg/dL. Zinc seems to only have glycemic benefit in patients living in the Eastern hemisphere, and not the Western hemisphere. Also, glucose reduction seems to be higher with inorganic zinc formulations at doses of at least 30 mg daily taken for at least one month (104080). Zinc has also been evaluated for improving lipid parameters in patients with diabetes. A meta-analysis of nine studies in patients with diabetes shows that taking zinc reduces triglycerides by 17 mg/dL, but does not seem to affect low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol levels, when compared with placebo (104041). The findings from these meta-analyses are limited by the high heterogeneity and small size of the included studies. Zinc has also been studied for gestational diabetes. Some clinical research in patients with gestational diabetes shows that taking zinc gluconate for 6 weeks, starting at 24-28 weeks' gestation, reduces fasting plasma glucose levels by about 10% and improves insulin resistance by 14% when compared to baseline (96072). However, taking zinc gluconate does not reduce the need for caesarean section or insulin therapy, or improve infant outcomes, such as size or health at birth, in these patients (96073).
Diaper rash. Topical and oral zinc seem to reduce the incidence and severity of diaper rash in infants. Details: Clinical research shows that administering oral zinc gluconate 10 mg daily for 4 months can reduce the incidence of diaper rash in infants when compared with placebo (87281). Other clinical research shows that applying 47% zinc oxide paste to affected areas for 5 days can improve the healing of diaper rash. However, the effect of zinc oxide paste is inferior to eosin 2% solution (86918).
Gingivitis. Topical zinc seems to reduce the development of gingivitis. Details: While some clinical research shows that zinc, in combination with triclosan, does not prevent plaque and gingivitis (24093,87020), most clinical research shows that using zinc toothpaste or mouthwash, alone or in combination with triclosan, can prevent plaque accumulation, gingivitis, or the formation of calculus (6523,6524,6525,6526,6527,6528,6529,87418,87507). However, most studies used zinc citrate in combination with triclosan, which is not available in the US (6523). For treating existing plaque, calculus, and gingivitis, some clinical research suggests that using zinc citrate 0.5% toothpaste three times daily for 3 months reduces calculus scores by 14% when compared with placebo (87205). However, other evidence suggests that stannous fluoride 0.454% toothpaste is more effective than zinc citrate 0.75% toothpaste for reducing plaque levels (87136).
Halitosis. Oral zinc seems to reduce halitosis when taken as a gum, mouth rinse, or candy. Details: Clinical research shows that chewing zinc-containing gum reduces volatile sulfur compounds and related odor levels when compared with placebo gum in patients with moderate to severe halitosis (87538). Clinical research also shows that using one of two mouth rinses (Halita, which contains 0.05% chlorhexidine and 0.14% zinc lactate, or Meridol, which contains 0.025% fluoride plus 0.2% zinc lactate) improves breath odor and volatile sulfur compounds by approximately two-fold when compared with mouth rinse containing only 0.05% fluoride or chlorhexidine 0.12% (90206). Additional clinical research shows that sucking a candy containing abrasive substances and zinc gluconate 0.5% or candy containing abrasive substances plus zinc 0.25% and propolis 1% improves breath malodor two- to three-fold when compared with sucking placebo candy (90196).
Herpes labialis (cold sores). Topical zinc seems to reduce the severity and duration of cold sores. Details: Applying zinc topically seems to help treat herpes simplex infection (6538,6539,8623,11051). Zinc sulfate seems to reduce the severity and duration of symptoms in both orolabial and genital herpes (6538,6539). Zinc oxide (0.3%) in combination with glycine cream applied topically every 2 hours to facial and circumoral herpes seems to reduce symptoms such as blistering, soreness, itching, and tingling. It can also reduce the duration of lesions from 6.5 days to 5 days when treatment is begun within 24 hours of onset of symptoms (8623). A specific combination product containing zinc oxide and L-lysine plus 14 other ingredients (Super Lysine Plus +) also seems to help decrease symptoms and duration of herpes lesions when applied topically every 2 hours (11051). However, zinc may not be effective for recurrent herpes simplex infections. In one clinical study, applying zinc sulfate 0.0025% or 0.05% solution to affected areas did not reduce the frequency, severity, or duration of herpes episodes when compared with a placebo solution in patients experiencing more than five episodes per year (87330).
Hypogeusia. Oral zinc might improve taste disturbance and taste acuity in people with hypogeusia of various etiologies. Details: A meta-analysis of low-quality studies in patients with taste disorders that are idiopathic or due to zinc deficiency shows that taking oral zinc modestly improves taste acuity when compared with placebo (104055). Studies tested zinc gluconate, zinc sulfate, zinc acetate, and zinc-carnosine as Polaprezinc (Promac, Zeria Pharmaceutical Co., Ltd.), containing 17-68 mg elemental zinc, daily for up to 12 weeks (104055). Zinc also might improve hypogeusia conditions unrelated to zinc deficiency, such as gustin/carbonic anhydrase VI deficiency, captopril-induced taste disturbances, hypogeusia due to chronic renal failure, and post-traumatic olfactory disorder (6543,6544,104055). It also seems be beneficial in radiation-induced dysgeusia. A meta-analysis of three small clinical trials shows that oral zinc reduces the risk of radiation-induced dysgeusia by 28%, but does not improve taste acuity when compared with placebo (104043). However, patients with hypogeusia from other causes may not benefit. Zinc supplementation does not seem to improve taste perception when compared with placebo in patients with acetazolamide-induced taste dysfunction or chemotherapy-induced taste dysfunction (87388,90214).
Leishmania lesions. Oral zinc and intralesional injections of zinc might improve healing of these lesions. Details: Clinical research shows that taking zinc sulfate 2.5-10 mg/kg orally in three divided doses daily, improves the cure rate of cutaneous leishmania lesions after 45 days when compared with no treatment (86935). Other clinical research shows that intralesional injections of zinc sulfate 2% solution for 6 weeks improves cure rates of cutaneous leishmania lesions when compared with no treatment (6587). However, intralesional injections with zinc sulfate solution does not appear to be more effective than intralesional injections of meglumine antimoniate (Glucantime), hypertonic saline, or sodium stibogluconate (6587,86996,87008).
Leprosy. Oral zinc seems to be beneficial when used in combination with anti-leprosy drugs. Details: Zinc levels appear to be reduced in people with leprosy. Early clinical research suggests that the addition of zinc improves tolerance of the anti-leprosy drug regimen and might allow for lowering or eliminating steroid doses in erythema nodosum leprosum, a severe form of leprosy (6534,6535,6536,6537).
Low birth weight. Oral zinc supplementation seems to improve growth in low birth weight infants. Whether oral zinc can improve other outcomes, including mortality, is unclear. Taking oral zinc during pregnancy does not seem to reduce the risk of having a low birth weight infant. Details: While there is some mixed evidence regarding the effects of zinc supplementation on weight gain and length in infants born with low birth weight (87172,87452,90229), a meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, increases weight by around 380 grams, length by around 3 cm, and head circumference by around 0.6 cm when compared with control (109455). There is also mixed evidence regarding the effect of zinc supplementation on other outcomes in low birth weight infants. A large clinical trial in full-term, underweight infants aged 1-6 months in developing countries shows that adding zinc to nutritional supplementation reduces the risk of mortality by about 68% when compared with nutritional supplementation not containing zinc (8920). A small clinical trial in very low birth weight preterm infants born in an industrialized country shows that adding zinc to multivitamin supplementation appears to reduce the occurrence of necrotizing enterocolitis and mortality. However, adding zinc does not appear to prevent late-onset sepsis, bronchopulmonary dysplasia, or retinopathy of prematurity (90229). A meta-analysis of these trials and two other studies in low birth weight infants shows that supplementation with zinc reduces the risk of all-cause mortality by 52% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). Another small clinical study in low birth weight and preterm infants born in a developing country shows that zinc supplementation seems to improve alertness and attention when compared with placebo (97140). However, a meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, does not improve mental or psychomotor development or reduce the risk of mortality, hospitalization, acute respiratory infection, or sepsis when compared with control (109455). Some of these discrepant findings may be due to differences in patient populations (hospitalized, non-hospitalized), milk sources (breastfed, formula-fed, or both), and duration of follow-up. The effect of zinc intake or supplementation during pregnancy has also been evaluated. Population research has found that low dietary intake of zinc during pregnancy is associated with low birth weight in infants; similarly, zinc supplementation is associated with increased infant weight at birth (87471,105678). However, a meta-analysis and a large clinical study show that zinc supplementation during pregnancy does not reduce the risk of having a low birth weight infant (97142,105679). Reasons for the discrepancies may be due to differing zinc status prior to supplementation. Also, numerous factors contribute to the risk of low birth weight, which may confound research on the use of zinc supplementation alone.
Peptic ulcers. Oral zinc seems to treat and prevent peptic ulcers. Details: Taking zinc orally seems to help treat and prevent peptic ulcers (6588,6589,6591). Some clinical research shows that zinc acexamate improves peptic ulcers when compared with placebo (6589,87285), and seems to be as effective as H2-receptor antagonist drugs (6589,87533). It is not known if other zinc salts are effective.
Pneumonia. Oral zinc might reduce the risk for pneumonia in children, but it doesn't seem to improve symptoms in children that already have pneumonia. Details: A meta-analysis of four clinical studies shows that giving zinc supplements to children, ages 3 months to 5 years living in developing countries, some of whom were undernourished, reduces the risk of pneumonia incidence by 21% when compared with placebo (104047). Another meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of pneumonia mortality by 21% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). The research on TREATING existing pneumonia in children is inconsistent. Most meta-analyses and clinical studies in children ages 2 months to 5 years with severe pneumonia show that taking elemental zinc in addition to antibiotic therapy does not improve symptom resolution or the time to recovery when compared with antibiotic therapy alone. Zinc also does not seem to reduce mortality in these patients (87248,90197,96080,98131,104042). However, two clinical studies in children in the same age group with pneumonia suggest that adding zinc to standard antibiotic therapy improves symptom resolution and decreases hospital stay when compared with placebo (11052,87242). Reasons for these discrepancies are not clear, but may be related to zinc status prior to treatment.
Prematurity. Analyses of clinical studies suggest that oral zinc improves growth in premature infants. Whether zinc improves development or reduces the risk of mortality in these patients is unclear. Details: A meta-analysis of small clinical trials in hospitalized infants born prematurely suggests that receiving enteral zinc supplementation at a dose of up to 10 mg daily reduces mortality and might improve short-term weight gain when compared with placebo (105687). Another meta-analysis of small clinical studies in preterm infants shows that adding zinc to formula or to a multivitamin seems to modestly increase infant weight and height and improve motor development when compared with control (105676). A larger meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, increases weight by around 380 grams, length by around 3 cm, and head circumference by around 0.6 cm when compared with control. However, zinc supplementation did not improve mental or psychomotor development or reduce the risk of mortality, hospitalization, acute respiratory infection, or sepsis when compared with control (109455). These analyses are limited by imprecision as well as a high risk of bias in some of the included studies. Some of the discrepant findings may be due to differences in patient populations (hospitalized, non-hospitalized), milk sources (breastfed, formula-fed, or both), and duration of follow-up.
Pressure ulcers. Topical zinc paste seems to work as a skin barrier and improve pressure ulcer healing. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that applying zinc oxide paste to pressure ulcers daily for 8 weeks reduces necrotic tissue and decreases the surface area of skin pressure ulcers similarly to using a topical streptokinase-streptodornase product (Varidase) (87331). Other small clinical studies show that applying zinc oxide paste to pressure ulcers daily for 8-12 weeks improves healing similarly to a hydrocolloid dressing (Duoderm) (87181) or a specific barrier film product (Cavilon No Sting Barrier Film) (87017). Oral zinc has been evaluated in combination with other ingredients for the treatment of grade II-IV pressure ulcers. Two small clinical studies in hospitalized patients shows that administering an oral nutritional supplement enriched with zinc, L-arginine, and vitamin C 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, zinc, L-arginine, and vitamin C 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.
Sickle cell disease. Oral zinc seems to improve symptoms of sickle cell disease in patients with zinc deficiency. Details: Taking zinc orally seems to help reduce symptoms of sickle cell disease in people with zinc deficiency (6594,6595,6596,8626,87343). Taking zinc supplements also seems to decrease the occurrence rate of sickle-cell crises and infections (6594,6596,90228). Additionally, zinc might reduce the number of hospitalizations for sickle cell crises, although the severity of the crises that do develop is not necessarily decreased by taking zinc supplements (6594,6596). In prepubertal children and adolescents with homozygous sickle cell disease, taking zinc seems to improve growth, height, and weight gain (8626,87403).
Warts. Oral and topical zinc seem to improve the cure rate of cutaneous warts. Details: A small clinical study suggests that applying zinc sulfate 10% solution three times daily for 4 weeks improves plane warts, but not common warts, when compared with distilled water (87094). Another small clinical study suggests that applying topical zinc oxide 20% ointment twice daily for up to 3 months seems to have a similar cure rate as ointment containing salicylic acid 15% with lactic acid 15% (87082). Taking zinc orally may also be effective in treating warts (87227). A meta-analysis of low quality clinical studies shows that taking zinc sulfate orally improves the odds of curing cutaneous warts nearly 17-fold when compared with respective controls (87227). Preliminary clinical research in adults treated with cryotherapy for anogenital warts shows that taking zinc gluconate 30 mg orally three times daily for 2 months does not reduce the number of warts when compared with placebo (111445).

POSSIBLY INEFFECTIVE

Alopecia areata. Oral zinc does not seem to improve symptoms of this condition. Details: Although there is preliminary evidence that suggests zinc in combination with biotin might be helpful for alopecia areata (6932), most studies indicate that zinc is not effective for alopecia areata, alopecia totalis, or alopecia universalis (6931,6932).
Cystic fibrosis. Oral zinc does not improve cystic fibrosis symptoms or progression. Details: Clinical research shows that taking supplements providing 30-90 mg of elemental zinc for 6 weeks to one year does not improve lung function when compared with placebo in children and adolescents with cystic fibrosis (87066,87113,96079). One clinical study also shows that taking elemental zinc for one year does not reduce the number of days requiring oral or intravenous antibiotics for pulmonary infections (96079). However, one study shows that taking zinc can reduce the number of days of oral antibiotic use when compared with placebo (87113).
HIV/AIDS. Oral zinc does not seem to improve outcomes in patients with HIV. Details: Clinical research in adult HIV patients with normal or low zinc levels shows that taking elemental zinc 12-15 mg daily orally for 18 months along with antiretroviral therapy does not improve viral load, CD4/8 counts, or mortality when compared with placebo (87036,87216,105686). In children with HIV-1, clinical research shows that administering zinc sulfate, providing 10 mg elemental zinc, daily for 6 months does not improve mortality, viral load, or CD4 counts when compared with placebo (82377).
HIV/AIDS-related pregnancy complications. Oral zinc does not prevent pregnancy complications related to HIV infection. Details: Adding zinc 25 mg orally during pregnancy does not seem to reduce parent-to-child vertical transmission of HIV, infant mortality, birth weight, or gestational period in HIV-infected females with low zinc levels (11054,87034). Also, one clinical study in HIV-1-infected pregnant patients suggests that supplemental zinc can increase the risk of wasting, as assessed by weight and mid-upper arm circumference, by 170% when compared with placebo (87034).
HIV/AIDS-related wasting. Oral zinc does not seem to improve HIV-related wasting syndrome. Details: A clinical study in patients with HIV-related wasting syndrome shows that taking zinc orally in combination with vitamins and albendazole does not seem to improve diarrhea or mortality when compared with taking albendazole alone (6564).
Infant development. Oral zinc does not seem to improve infant mental and psychomotor development. Details: Clinical research, including a meta-analysis of eight studies, shows that giving zinc to infants or children at high risk for zinc deficiency does not improve mental and psychomotor development when compared with placebo (87013,90209). In another meta-analysis of studies in children whose baseline zinc status was not specified, there was no beneficial effect of zinc supplementation on mental or psychomotor development at 6 or 12 months of age (104817).
Inflammatory bowel disease (IBD). Oral zinc does not improve symptoms of IBD. Details: Some clinical research shows that taking zinc orally does not seem to help treat IBD (6913,6915,6916).
Influenza. Oral zinc does not seem to reduce the risk for influenza. Details: Supplemental zinc seems to improve cell-mediated immune response in elderly people (824), but it does not seem to have a significant effect on antibody response and incidence of influenza infection after the vaccine (6553,6563). Additionally, zinc supplementation in patients on hemodialysis, who have a high risk of zinc deficiency, does not seem to improve response to influenza vaccine (10809). Taking zinc supplements orally is unlikely to improve immune function in people without risk factors for zinc deficiency (10789). However, there is preliminary evidence that suggests zinc along with selenium might reduce the incidence of infections in institutionalized older patients (8921).
Otitis media. Oral zinc does not prevent otitis media in children. Details: A meta-analysis of clinical research shows that taking elemental zinc 3-70 mg daily for up to 24 months does not prevent the occurrence of ear infections in children from low- or middle-income countries (87258).
Pre-eclampsia. Oral zinc taken prenatally does not seem to be beneficial for pre-eclampsia prevention. Details: A meta-analysis and a large clinical study show that zinc supplementation during pregnancy does not reduce the risk of pre-eclampsia when compared with placebo (97142,105679).
Prostate cancer. Oral zinc does not reduce the risk for prostate cancer or prostate cancer-related mortality. Details: Some epidemiological research has found an inverse relationship between dietary zinc intake and prostate cancer (96075). Also some clinical research shows that taking zinc 20 mg in combination with vitamin C 120 mg, vitamin E (alpha-tocopherol) 30 mg, beta-carotene 6 mg, and selenium 100 mcg daily for an average of 8 years might reduce the risk of prostate cancer in men with normal PSA levels; however, it does not seem to be beneficial for reducing the risk of prostate cancer in patients with PSA levels above 3 mcg/L (14135). However, some evidence raises concern that zinc might actually INCREASE the risk of prostate cancer. A large-scale population study found that taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer (10306). Another large-scale population study shows that men who take a multivitamin more than seven times per week and who also take a separate zinc supplement have a significantly increased risk of prostate cancer-related mortality (15607). Despite these studies suggesting the potential for adverse effects of zinc, a meta-analysis of mainly population research has found that there is no association between zinc intake and the risk of prostate cancer (96075).
Psoriasis. Oral zinc does not reduce the severity of psoriasis symptoms. Details: Zinc epidermal levels are reportedly lower in people with psoriasis (6509). However, taking zinc orally does not seem to help treat psoriasis (6513,6514,6912,87363). Zinc supplementation has no effect on the psoriasis area and severity index (6513,6514).
Rheumatoid arthritis (RA). Oral zinc does not treat symptoms of RA. Details: Multiple clinical studies in patients with RA show that taking zinc orally does not improve function or symptoms when compared with baseline or control (6517,6518,6519,87406).
Sexual dysfunction. Oral zinc does not improve sexual function in males with chronic kidney disease (CKD). Details: Clinical research shows that zinc supplementation does not improve sexual activity or libido when compared with placebo in males with sexual dysfunction secondary to CKD (6708,6568,87220,87386,87416). In fact, one clinical study shows that taking zinc can decrease the frequency of intercourse by 76% when compared with placebo in patients with CKD-related sexual dysfunction (87220).
Tinnitus. Oral zinc does not improve severity of tinnitus or reduce tinnitus-related disability. Details: A meta-analysis of three small clinical trials in adults with tinnitus shows that taking elemental zinc 50 mg daily for up to 16 weeks does not improve tinnitus severity, or disability from tinnitus when compared with placebo (104051).

LIKELY INEFFECTIVE

Malaria. Oral zinc does not prevent or treat malaria in undernourished children or pregnant adults in developing countries. Details: A meta-analysis of clinical research in children or pregnant adults shows that taking zinc orally, alone or in combination with other supplements, for does not reduce the risk of malaria parasitemia (111444). A large multi-country study in zinc-deficient preschool children with acute malaria shows that taking zinc supplements does not affect fever, parasitemia, or hemoglobin when compared with placebo (10246). An even larger clinical study of over 40,000 children with malaria aged 1-36 months shows that taking zinc 5-10 mg daily orally for approximately 17 months does not reduce mortality when compared with placebo (87078). Zinc supplements also do not appear to protect against infection by Plasmodium falciparum (8638,87235,86937). However, one small study in children with low and high levels of parasitemia shows that taking zinc 10 mg daily for 46 weeks may lower the incidence of fever episodes by 38% and 69%, respectively, when compared with placebo (86937).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Age-related cognitive decline. It is unclear if oral zinc is beneficial in patients with age-related cognitive decline. Details: An epidemiological study based on elderly adults enrolled in the National Health and Nutrition Examination Survey (NHANES) has found that taking zinc may improve cognition in a non-linear manner. Daily doses below 9 mg and 8 mg in males and females, respectively, showed a positive association with cognitive function, but doses above that level showed no association. Additionally, high intake of both zinc and selenium was associated with improved cognition in females, but not in males (108446). Dietary intake was collected from two patient-reported 24-hour recalls and cognition was only measured once, limiting the validity of these findings.
Alcohol-related liver disease. It is unclear if oral zinc is beneficial in patients with alcoholic-related liver cirrhosis. Details: A small clinical study in patients with alcoholic liver cirrhosis shows that taking zinc sulfate 600 mg daily for 6 weeks improves liver function, based on increased alkaline phosphatase activity and reduced serum bilirubin, when compared to baseline (87325).
Anorexia nervosa. Oral zinc seems to improve weight gain in people with anorexia nervosa. Details: Anorexia nervosa might be linked with zinc deficiency. Small clinical trials in adolescents and adults with anorexia nervosa show that oral zinc supplements might help increase weight gain and improve depressive symptoms when compared with placebo (6905,6906).
Arsenic poisoning. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that taking zinc 4 mg in combination with spirulina extract 500 mg daily for 16 weeks can decrease skin manifestations and reduce arsenic levels in the urine and in hair of patients with chronic arsenic poisoning (18301).
Asthenopia (eye strain). Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in adults without dry eye disease shows that taking a specific combination product containing zinc 10 mg, L-carnitine 50 mg, elderberry fruit extract 300 mg, currant 100 mg, and Eleutherococcus root 50 mg (Meramirt CM) orally once daily for 1 month improves measures of eye strain and contrast sensitivity when compared to baseline. Improvements in these measures were lacking in the control group (111295). Statistical comparison between the two groups was not reported. It is unclear if these effects are due to zinc, other ingredients, or the combination.
Athletic performance. Although there is interest in using oral zinc for athletic performance, there is insufficient reliable information about the effects of zinc for this purpose.
Atopic dermatitis (eczema). It is unclear if oral zinc is beneficial for alleviating eczema in children. Details: A small clinical study in children with eczema shows that taking zinc sulfate 185.4 mg orally daily for 8 weeks does not appear to improve the surface area affected and degree of erythema, symptom scores of itch and sleep disturbance, or topical steroid use when compared with placebo. Also, plasma zinc levels appear to be normal in children with eczema (6911).
Attention deficit-hyperactivity disorder (ADHD). Oral zinc might improve certain symptoms in children with ADHD. Details: Observational research has found that lower serum zinc levels are both more prevalent in children with ADHD and are linked to worsened response to stimulant therapy (9965,9966,9967). Based on this evidence, there is some interest in using zinc to improve symptoms in children with ADHD. A meta-analysis of six small clinical trials shows that although taking zinc modestly improves overall symptoms of ADHD when compared with placebo, there is no effect on hyperactivity or inattention when these outcomes are examined separately. The sub-analyses conducted for these two separate outcomes included only 3 studies. Most, but not all, of the included studies were conducted in children also receiving methylphenidate treatment (106240). Elemental zinc, usually as sulfate, was typically used in doses of 10-40 mg daily for 6-12 weeks (11350,12060,106240). There is some evidence that zinc could be most helpful in children with a high body mass index (BMI), low zinc levels, and low free fatty acid levels (11350). It is unclear if zinc is beneficial in children who are not already taking stimulant medications. One clinical guideline also provisionally recommends against use of oral zinc to treat patient with ADHD based on low-quality evidence (110318).
Autism spectrum disorder. It is unclear if oral zinc is beneficial in children with autism spectrum disorder. Details: One small clinical study conducted in children with autism spectrum disorder shows that taking zinc 15-30 mg orally, alone or as add-on therapy to amphetamine, does not improve attention deficit hyperactivity disorder (ADHD) symptoms when compared with placebo (98711). However, the optimal mg/kg dose of amphetamine was shown to be 37% lower for those children also taking zinc 15 mg twice daily when compared with those taking placebo (98711).
Behcet disease. It is unclear if oral zinc is beneficial in patients with Behcet disease. Details: A small clinical trial in patients with Behcet disease shows that taking zinc gluconate 30 mg daily for 12 weeks does not improve disease activity scores, quality of life, or measures of inflammation when compared with placebo (109453).
Benign prostatic hyperplasia (BPH). Although there is interest in using oral zinc for BPH, there is insufficient reliable information about the clinical effects of zinc for this condition.
Beta-thalassemia. It is unclear if oral zinc is beneficial in patients with beta-thalassemia major. Details: A small clinical study in children recently diagnosed with beta-thalassemia major shows that initiating zinc sulfate in addition to standard blood transfusions increases linear growth rate when compared with transfusions alone (87329). Another small clinical study in adult and pediatric patients with thalassemia major and low bone mass shows that taking zinc 25 mg daily (as zinc sulfate) for 18 months improves whole-body bone mineral content, as well as hip and spine bone mineral density, by small amounts when compared with placebo (90208).
Brain tumor. It is unclear if dietary zinc is beneficial for reducing the risk for brain cancer. Details: Population research has found that zinc intake is not associated with a reduced risk of developing brain cancer (87098).
Breast cancer. It is unclear if increased dietary zinc intake is beneficial for reducing the risk for breast cancer. Details: Population research has found that neither zinc intake nor blood levels of zinc are associated with a reduced risk of breast cancer (106229).
Bronchiolitis. It is unclear if oral zinc is beneficial for viral bronchiolitis in infants and children. Details: A small clinical study in children 2 years or younger with acute viral bronchiolitis shows that taking elemental zinc 10-20 mg as zinc sulfate for 5 days improves clinical recovery and reduces the duration of hospital stay by almost one day when compared with placebo. After 72 hours, 98% of infants and children taking zinc were considered fully recovered, compared to only 52% of infants taking placebo (96076).
Burning mouth syndrome. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with burning mouth syndrome shows that taking zinc 15 mg and vitamin C 35 mg once daily, along with a vitamin B complex twice daily, for 30 days modestly decreases pain and burning when compared to baseline (105195). The validity of this finding is limited by the lack of a comparator group. Furthermore, it is unclear if the benefit is due to zinc, other vitamins, or the combination.
Burns. Intravenous zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. The effects of oral zinc for burn healing are unclear. Details: Administering zinc intravenously in combination with other minerals seems to improve the outcomes of burn patients. Supplementation with zinc, copper, and selenium appears to improve wound healing, reduce pulmonary infections, and shorten intensive care unit stay in patients with serious burns (6520,87085). The effect of supplementation with zinc alone is unclear.
Canker sores. It is unclear if oral zinc is beneficial in patients with canker sores. Details: Evidence for the use of zinc in canker sores is conflicting. A small clinical crossover study in patients with recurrent canker sores shows that taking zinc sulfate 660 mg daily for 3 months does not improve the size or frequency of canker sore ulcers when compared with control (6592). However, another clinical study in patients with recurrent sores and low or normal zinc levels shows that taking zinc sulfate 220 mg daily for 1 month reduces recurrence of sores when compared with placebo (86964). Reasons for conflicting results are unclear. Zinc might be beneficial when used in a muco-adhesive formulation. A small clinical study in patients with canker sores shows that taking a muco-adhesive zinc sulfate 5 mg tablet three times daily for 7 days reduces pain and speeds up healing when compared with placebo (104048).
Cataracts. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking zinc orally in combination with antioxidant vitamins does not seem to help treat or prevent cataracts. Taking elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily does not seem to have any effect on the development or progression of age-related lens opacities (cataracts) or the need for cataract surgery in well-nourished people 55-80 years of age. However, it is unknown whether earlier intervention and/or a longer period of treatment with supplements would have any effect on cataracts (7304).
Chemotherapy-induced acral erythema. It is unclear if oral zinc reduces the severity of acral erythema induced in patients treated with the vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) treatment regorafenib. Details: A small study in patients with metastatic colorectal cancer undergoing treatment with regorafenib shows that taking zinc gluconate 78 mg twice daily reduces the proportion of patients with more severe acral erythema when compared with control. Though there is no association in the zinc treatment group, lower serum zinc levels seem to correlate with more severe acral erythema in the control group, suggesting a possible role of zinc deficiency in the pathogenesis of acral erythema (112472). The validity of this study is limited by the lack of blinding.
Chemotherapy-related fatigue. It is unclear if oral zinc improves symptoms in patients with fatigue due to chemotherapy. Details: A small clinical study in patients undergoing 4 or more cycles of chemotherapy for colorectal cancer shows that taking zinc 70 mg daily for 16 weeks does not improve fatigue or quality of life when compared with placebo (97141).
Chronic fatigue syndrome (CFS). Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in females with CFS shows that taking zinc 10 mg as zinc sulfate plus melatonin 1 mg daily for 16 weeks modestly reduces self-reported symptoms of physical fatigue when compared with placebo. However, there was no effect on cognitive or psychological symptoms, sleep, or symptoms of anxiety or depression (106241). This study may not have been adequately powered to detect differences between groups.
Cirrhosis. It is unclear if zinc is beneficial for reducing cirrhosis-related mortality. Details: A meta-analysis of four small clinical trials shows that zinc supplementation does not seem to reduce mortality in patients with cirrhosis when compared with control (104054). This finding is limited due to the heterogeneity and small size of the available studies.
Cognitive function. It is unclear if zinc is beneficial for cognitive function. Details: A very small clinical study in adults with overweight and obesity shows that taking supplemental zinc 30 mg daily for 12 weeks improves some measures of cognitive function and executive processing but does not improve verbal fluency when compared with placebo (112471). Zinc has also been evaluated in combination with other ingredients. A small clinical trial in healthy adults shows that taking a specific product containing a combination of zinc 9 mg, Lactobacillus helveticus, Lactiplantibacillus plantarum, Bifidobacterium longum, and other ingredients (Puraflor, GSK Consumer Healthcare, Milano, Italy) orally daily for 4 weeks does not affect cognitive performance during acute stress when compared with placebo (110923).
Colorectal adenoma. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study shows that taking a combination supplement containing zinc 30 mg, selenium 200 mcg (as l-selenomethionine), vitamin A 2 mg (as retinol), vitamin C 180 mg, and vitamin E 30 mg (as D-a-tocopherol acetate) by mouth daily for 5 years or until the recurrence of an adenoma reduces the risk of recurrent large-bowel adenomas by approximately 40% when compared with placebo (92903). It is not clear if the benefit is due to zinc, other supplements, or the combination.
Colorectal cancer. It is unclear if oral zinc is beneficial for reducing colorectal cancer risk. Details: Population research has found that increased intake of zinc is associated with a 17% to 20% reduced risk of colorectal cancer (90213,90220).
Congenital heart disease. It is unclear if oral zinc is beneficial for reducing the risk of congenital heart defects. Details: An observational study in pregnant adults has found that consuming the recommended nutritional intake of zinc may be associated with a lower risk of total congenital heart defects in infants, including atrial and ventricular septal defects, when compared with low zinc intake. This association appears to persist despite copper or selenium intake (108445).
Critical illness (trauma). It is unclear if oral zinc is beneficial for critically ill patients. Details: A meta-analysis of two small randomized clinical trials in adults with head trauma shows that supplementing zinc, given as 120 mg elemental zinc orally daily or 12 mg elemental zinc intravenously daily for 15 days to 3 months, regardless of serum zinc levels, does not improve the risk of 30-day mortality when compared with control (111290). However, the study may have been inadequately powered to detect a difference between groups.
Dementia. Although there is interest in using oral zinc for dementia, there is insufficient reliable information about the clinical effects of zinc for this condition.
Diabetic foot ulcers. Although there is interest in using oral zinc for diabetic foot ulcers, there is insufficient reliable information about the clinical effects of zinc for this condition.
Diabetic neuropathy. It is unclear if oral zinc is beneficial in patients with diabetic neuropathy. Details: A small clinical study in patients with poorly-controlled diabetic neuropathy shows that taking zinc sulfate 660 mg daily for 6 weeks improves motor nerve conduction velocity and reduces fasting and postprandial blood sugar when compared to baseline (86933). The validity of this finding is limited by the lack of statistical comparison to the control group.
Down syndrome. It is unclear if oral zinc is beneficial for improving immune function in people with this condition. Details: A very small clinical study in Down syndrome patients with zinc deficiency shows that taking zinc sulfate 1 mg/kg daily for 2 months seems to improve immune function and reduce recurrent infections when compared with baseline (87289). The validity of this finding is limited by the lack of a control group. Another small clinical study in children with Down syndrome shows that zinc 25-50 mg daily for 6 months does not improve immune function when compared with placebo (87278). Reasons for the discrepancies may be related to the dose of zinc or zinc status at baseline.
Dysmenorrhea. It is unclear if oral zinc is beneficial in patients with dysmenorrhea. Details: Preliminary clinical research in females aged 13 to 21 years with primary dysmenorrhea shows that taking zinc sulfate 40 mg orally daily for the first 3 days of menstruation for three cycles reduces mean pain scores by 51% when compared with placebo (111446).
Epilepsy. There is limited evidence on the oral use of zinc in children with intractable seizures. Details: A small clinical study in children with intractable epilepsy shows that taking elemental zinc 1 mg/kg daily as zinc sulfate heptahydrate for 6 months reduces seizures when compared with placebo. About 31% of children taking zinc experienced a 50% decrease in seizure frequency, compared to only 5% of children taking placebo (96078).
Esophageal cancer. It is unclear if oral zinc is beneficial for esophageal cancer prevention. Details: Population research in Chinese and Iranian patients has found that low intake of zinc is associated with an increased risk of esophageal squamous cell cancer (17205,87059). However, other population research in patients from America, Europe, or Asia has found that dietary zinc intake is not associated with esophageal cancer risk (90213).
Fatigue. It is unclear if oral zinc is beneficial for reducing fatigue in older individuals. Details: A clinical study in adults 50 years and older, some with below-normal levels of zinc at baseline, shows that taking zinc 30 mg daily for 70 days improves subjective fatigue when compared with no intervention (105675). The validity of this finding is limited due to a lack of placebo control and potential performance bias. Additionally, it is unclear whether baseline zinc status alters the benefits of zinc supplementation.
Fecal incontinence. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in females with fecal incontinence shows that topically applying an ointment containing zinc sulfate 1% and aluminum sulfate 5% to the anal canal mucosa three times daily for 4 weeks improves symptoms approximately twice as much as a placebo ointment. Quality of life related to the incontinence also improved (90219).
Gastric cancer. It is unclear if dietary zinc is beneficial for gastric cancer prevention. Details: Population research has found that increased dietary zinc intake is not associated with a decreased risk of gastric cancer (90213).
Head and neck cancer. It is unclear if oral zinc improves survival in patients with head and neck cancers. Details: Preliminary clinical research in patients with head and neck cancers shows that zinc supplementation does not improve disease-free or metastasis-free survival rates after 3 years when compared with placebo (87103).
Hepatic encephalopathy. It is unclear if oral zinc is beneficial for reducing the severity of hepatic encephalopathy or preventing recurrence. Details: A meta-analysis of small clinical studies, as well as some individual clinical studies, show that short-term zinc supplementation improves cognitive function and possibly quality of life in patients with hepatic encephalopathy. These findings are based on results from the number connection test and other tests (87377,90202,106227). One study in patients with minimal hepatic encephalopathy used zinc bisglycinate 75 mg three times daily, providing elemental zinc 45 mg daily for 12 weeks (106227). However, other preliminary clinical research shows that short-term zinc supplementation does not improve hepatic encephalopathy severity when compared with placebo when assessed using Conn's index, which includes evaluation of mental state, asterixis (flapping tremor), number connection test, electroencephalogram (EEG) record, and plasma ammonia (87144). Also, a meta-analysis of clinical research shows that zinc sulfate supplementation does not reduce encephalopathy recurrence (90202). Based on these results, zinc supplementation may marginally improve cognitive function in hepatic encephalopathy patients, but it does not appear to improve disease severity or reduce the risk of recurrence.
HIV/AIDS-related diarrhea. It is unclear if oral zinc is beneficial for preventing diarrhea in adult HIV patients. Details: Short-term zinc supplementation does not appear to TREAT diarrhea in adult HIV patients with persistent diarrhea. Clinical research shows that taking zinc 50 mg twice daily for 7 days does not reduce the duration of HIV-related diarrhea when compared with placebo (87055). However, zinc supplementation may help PREVENT HIV-related diarrhea when administered long-term. Clinical research shows that taking elemental zinc 12-15 mg daily for 18 months reduces the rate of diarrhea by about half when compared with placebo in adult HIV patients with zinc deficiency (87216). In HIV-infected children, clinical research shows that taking elemental zinc 10 mg daily for 6 months can reduce the occurrence of diarrhea by 49% when compared with placebo (82377). However, administering zinc in combination with vitamin A until 2 years of age does not reduce the occurrence of diarrhea when compared with vitamin A alone in HIV-infected children (82417).
HIV/AIDS-related opportunistic infections. It is unclear if oral zinc is beneficial in opportunistic infections in patients with HIV/AIDs. Details: A small clinical study in patients with AIDS shows that taking zinc supplements orally in combination with zidovudine (AZT, Retrovir) might reduce opportunistic infections of Pneumocystis carinii and Candida when compared with taking zidovudine without zinc (6566).
Human papillomavirus (HPV). It is unclear if oral zinc is beneficial for preventing relapse in patients with vulvar warts or for treating HPV infections and cervical lesions in patients with abnormal cervical cytology. Details: One small clinical study in patients with vulvar warts shows that taking zinc sulfate 400 mg daily for 8 weeks in addition to topical treatments including podophyllin 20%, imiquimod 5%, or cryotherapy, does not affect the duration of response, but does reduce the relapse rate by approximately 66% after 6 months, when compared with topical treatments alone (90190). Additionally, a small, open-label study in zinc-sufficient females with HPV shows that taking zinc sulfate 220 mg twice daily for 3 months reduces the odds of persistent HPV infection by 87% and improves the resolution of pre-existing cervical lesions when compared with no treatment (109456).
Hypertension. It is unclear if oral zinc reduces blood pressure in normotensive or hypertensive patients. Details: A meta-analysis of small clinical trials shows that taking zinc reduces systolic blood pressure by about 1.5 mmHg, but does not reduce diastolic blood pressure, when compared with placebo. Response did not differ with the dosage of zinc or duration of supplementation. Only one study evaluated patients with hypertension; other patient populations included those with type 2 diabetes, diabetic retinopathy, pre-diabetes, obesity, polycystic ovary syndrome (PCOS), and patients on dialysis (104052). More research in patients with hypertension is needed to determine if zinc is beneficial in this population.
Impaired glucose tolerance (prediabetes). While some conflicting evidence exists, several small clinical studies suggest that oral zinc may improve glycemic control in patients with prediabetes. Details: A meta-analysis of three low-quality studies in patients with prediabetes suggests that taking zinc sulfate 20-30 mg, alone or in combination with lysine and vitamin C, for 6-12 months reduces fasting blood glucose and postprandial glucose when compared with control (105682). Furthermore, a small clinical study in patients with prediabetes shows that taking zinc gluconate 30 mg daily for 90 days improves glycemic parameters when compared with placebo. All study participants were also instructed to increase physical activity and start a calorie-restricted diet (105391). However, another small clinical study in patients with prediabetes shows that taking zinc gluconate 30 mg daily for 12 months does not improve glycemic parameters when compared with placebo (109454). The available research has been conducted in Sri Lanka, Bangladesh, Iran, and Australia; it is unclear if these findings are generalizable to other geographic locations.
Intestinal parasite infection. It is unclear if oral zinc is beneficial in patients with intestinal parasitic infections. Details: Zinc supplementation may help TREAT infection from Schistosoma mansoniin, but not other parasites, in children in developing countries. Results from one clinical study show that taking oral zinc sulfate 30-50 mg for 12 months reduces the intensity of Schistosoma mansoniin infection in children, as measured by number of eggs per gram in feces, when compared with placebo (87495). However, supplementation with zinc does not appear to reduce the intensity of Ascaris lumbricoides, Trichiuris trichura, nor Giardia lamblia infection in children (6586). Furthermore, preliminary clinical research suggests that supplementation with zinc may increase the duration of Entamoeba histolytica infection in children (87099). There are also inconsistent results regarding the effects of zinc in PREVENTING intestinal parasite infections. Some clinical research shows that taking zinc in combination with vitamin A reduces the incidence of Giardia lamblia infections when compared with placebo (87099). However, zinc supplementation does not appear to prevent intestinal infections by Ascaris lumbricoides, Schistosoma haematobium, nor Schistosoma mansoniin (87099,87495).
Kidney failure. It is unclear if oral zinc is beneficial for patients on hemodialysis who have resistance to erythropoiesis-stimulating agents (ESAs). Details: Zinc deficiency is thought to play a role in ESA-resistant anemia in patients with kidney failure. A small clinical trial in patients on hemodialysis with low zinc levels shows that taking zinc acetate hydrate, usually 25mg or 50 mg daily, for 12 months increases plasma levels of zinc and modestly reduces the required weekly dose of ESAs when compared with placebo. However, there was no effect on hemoglobin levels (109781).
Leukemia. It is unclear if oral zinc is beneficial for improving weight maintenance in children and adolescents with leukemia. Details: A small clinical study in children and adolescents with acute leukemia shows that taking zinc 2 mg/kg (as an amino acid salt) in two divided doses daily for 60 days doubles weight gain and reduces infection rate by approximately 60% when compared with placebo. However, zinc supplementation does not appear to improve nutritional status (90204).
Liver cancer. It is unclear if oral zinc is beneficial for preventing hepatocellular carcinoma (HCC). Details: In patients treated for hepatitis C, the presence of hepatic fibrosis increases the risk for development of HCC, and is also associated with low plasma zinc levels. In a retrospective analysis of patients with a sustained virological response to hepatitis C therapy, those taking oral zinc supplements for at least 6 months had approximately half the risk of developing HCC when compared with those not taking zinc. Maintaining a serum zinc level above 90 mcg/dL seems to reduce the risk for HCC (106904).
Lung cancer. It is unclear if increased dietary zinc intake is beneficial for reducing the risk of lung cancer. Details: Population research has found that the highest dietary intake of zinc is associated with a 32% reduced risk of lung cancer when compared with the lowest intake (106235).
Male infertility. It is unclear if oral zinc is beneficial for infertility in males. Details: Some preliminary clinical research shows that taking zinc sulfate 66 mg daily increases sperm count, testosterone levels, and the incidence of pregnancy in idiopathic infertile men with low testosterone levels (9334,87430). Another clinical study shows that taking zinc sulfate 66 mg daily can improve sperm morphology by approximately 33% when compared to baseline in men with a grade III varicocele (90194). However, not all research agrees. One clinical study shows that taking elemental zinc 30 mg with folic acid 5 mg daily for 6 months does not improve sperm morphology or pregnancy rates when compared with placebo in infertile men (102085). It is possible the lower dose used in this study was insufficient to produce the beneficial effects observed in earlier research. Zinc supplementation has also been studied as part of combination therapy. A retrospective study in males with or without varicocele-related infertility has found that taking a specific combination product containing zinc 10 mg, L-carnitine fumarate 1725 mg, acetyl-L-carnitine 500 mg, vitamin C 90 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. Improvements 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). There is also interest in using zinc to improve results of in vitro fertilization (IVF). A small clinical study in couples undergoing IVF suggests that infertile male partners who take a specific combination product (Menevit) containing zinc and other antioxidants seem to have an increased rate of viable pregnancies when compared with placebo (87087). However, it's unclear if the benefit can be attributed to zinc, other antioxidants, or the combination.
Melasma. It is unclear if topical zinc reduces melasma severity. Details: A small clinical study shows that applying a topical solution containing zinc sulfate 10% once daily for 2 months is less effective at reducing melasma severity when compared with hydroquinone 4% (90232).
Menopausal symptoms. It is unclear if oral zinc improves sexual function after menopause. Details: A single clinical trial shows that taking zinc sulfate 110 mg daily for 6 weeks modestly improves testosterone levels and sexual function, including desire, arousal, satisfaction, and pain, after menopause when compared with placebo (106228).
Migraine headache. It is unclear if oral zinc is beneficial in patients with migraine. Details: Two small clinical studies in patients with migraine show that taking zinc sulfate 200 mg or zinc gluconate 15 mg daily for 8-12 weeks modestly reduces migraine severity and frequency when compared with placebo (104040,105684). Both studies were conducted in Iran; it is unclear if these findings are generalizable to other geographic locations.
Nasopharyngeal cancer. It is unclear if oral zinc is beneficial in patients with this type of cancer. Details: A small clinical study in patients with locally advanced nasopharyngeal cancer shows that zinc supplementation 75 mg daily for 2 months may improve disease-free survival rates after 5 years when compared with placebo (87163).
Neonatal jaundice. It is unclear if oral zinc is beneficial for neonatal jaundice. Details: Two small clinical studies in infants with idiopathic neonatal hyperbilirubinemia show that receiving oral zinc sulfate 5 mg twice daily for 5-7 days does not affect levels of total bilirubin, the required duration of phototherapy, or the duration of hospitalization, when compared with placebo (90212,104814). A larger clinical trial suggests that this lack of effect may be due to the need for a longer treatment duration. In preterm infants receiving phototherapy and zinc 1.2 mg/kg daily as zinc sulfate heptahydrate, via either orogastric or nasogastric tube for 10 days, serum bilirubin levels were modestly decreased only on days 8-10 when compared with phototherapy alone (106242).
Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral zinc is beneficial in patients with NAFLD. Details: A small clinical study in patients with NAFLD shows that following a calorie-restricted diet and taking zinc 30 mg daily for 12 weeks reduces certain liver enzymes, but does not improve steatosis or reduce weight, when compared with taking placebo and following a calorie-restricted diet (104046).
Non-Hodgkin lymphoma. It is unclear if oral zinc is beneficial for non-Hodgkin lymphoma prevention. Details: Population research has found that higher dietary intake of zinc is associated with a 42% decreased odds of developing non-Hodgkin lymphoma (87048).
Obesity. Small studies suggest that oral zinc does not reduce weight or calorie intake in people with overweight or obesity. Details: A very small clinical study in adults with overweight or obesity shows that taking supplemental zinc 30 mg daily for 12 weeks does not reduce body weight, body mass index (BMI), calorie intake, or macronutrient intake when compared with placebo (112471). Additionally, clinical research in adults with overweight or obesity shows that taking zinc gluconate 25 mg and L-selenomethionine 200 mcg once daily for 8 weeks does not improve BMI, total body fat, or fat free mass when compared with placebo (111448).
Obsessive-compulsive disorder (OCD). It is unclear if oral zinc reduces symptoms in patients with OCD. Details: A small clinical study in patients with OCD shows that taking zinc sulfate 200 mg twice daily with fluoxetine 20 mg daily for 8 weeks modestly reduces the severity of OCD symptoms when compared with taking placebo with fluoxetine (90223).
Oral mucositis. It is unclear if oral or topical zinc prevents oral mucositis due to chemotherapy. Some small clinical studies suggest that oral zinc might prevent mucositis due to radiotherapy. Details: Two small clinical studies in adults with leukemia and other cancers shows that taking zinc sulfate 220 mg three times daily for 14 days or until the end of chemotherapy treatment reduces oral mucositis and pain intensity when compared with placebo (90191,98132). However, smaller doses have not shown benefit. A small clinical study in children and adolescents with leukemia shows that taking zinc 2 mg/kg daily (up to 60 mg daily) in two divided doses does not affect chemotherapy-induced mucositis when compared with placebo (90204). An unblinded clinical study in children and adolescents aged 8-16 years with recently diagnosed leukemia shows that taking zinc gluconate 50 mg (7 mg elemental zinc) daily does not significantly reduce the incidence or duration of oral mucositis when compared with a control group not receiving zinc (104816). Zinc also doesn't seem to be beneficial with high-dose chemotherapy. A small clinical study in adolescents and adults receiving high-dose chemotherapy prior to undergoing hematopoietic stem cell transplantation (HSCT) suggests that taking zinc sulfate 220 mg (50 mg elemental zinc) twice daily, beginning one day prior to the chemotherapy regimen and continuing for 3 weeks, does not affect the severity, duration, or onset of mucositis when compared with placebo (90215). Other preliminary clinical research in children aged 3-18 years receiving chemotherapy for leukemia or other cancer also shows that taking zinc 1 mg/kg orally daily for 14 days, beginning on the first day of chemotherapy, does not reduce the incidence or severity of mucositis when compared with placebo (111447). Topical zinc has also been investigated for radiation-induced or chemotherapy-induced oral mucositis. In two clinical studies, using 7.5 mL of a mouthwash containing zinc chloride 0.2% twice for 2 minutes every 8 hours for 3 weeks modestly reduces the incidence and severity of oral mucositis, and improves quality of life, when compared with a placebo mouthwash (106232,109690). In one study, the average patient weight was higher in the group using the mouthwash containing zinc (106232). Other preliminary clinical research in adults with head and neck cancer undergoing radiotherapy treatment, consisting of at least 30 Gy radiation exposure shows that using zinc sulfate 1% mouthwash, 5 mL three times daily for 6 weeks, beginning on the first day of radiation therapy, moderately improves oral mucositis severity and pain scores when compared with chlorhexidine 0.2% or placebo mouthwash (111291). Taking zinc orally might be beneficial in radiation-induced oral mucositis. A small clinical study in patients with head and neck tumors shows that taking zinc sulfate, providing 150 mg elemental zinc, daily starting at the first day of radiation therapy and ending at 6 weeks, reduces the severity of mucositis and prolongs the onset of mucositis when compared with placebo (86981). Another clinical study in patients with head and neck cancer shows that taking zinc sulfate 150 mg daily during and after chemoradiotherapy treatment, consisting of a total 69.5 Gy radiation exposure and cisplatin 40 mg/m2 weekly, is associated with less severe mucositis when compared with placebo (105677).
Osteoporosis. It is unclear if oral zinc improves bone density in patients with osteoporosis. Details: Population research has found that reduced zinc intake and lower zinc serum levels seem to be associated with lower bone mineral density (BMD) (6920,14410). In elderly patients with at least marginal zinc deficiency who are taking standard therapy for osteoporosis, preliminary clinical research shows that taking zinc acetate dihydrate (Nobelzin, Nobelpharma) providing elemental zinc 25 mg twice daily for 12 months increases BMD when compared with baseline. Increases in serum zinc were associated with improvements in BMD. However, it is unclear if increases in BMD were significant when compared with placebo (106230). It is also unclear if zinc improves BMD in patients without zinc deficiency. A small clinical study in healthy postmenopausal adults suggests that taking zinc in combination with copper, manganese, and calcium might slow bone loss when compared with placebo (1994). It is not clear if this effect is due to zinc, other ingredients, or the combination.
Overall mortality. It is unclear if oral zinc reduces overall mortality in young children. Details: A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc in daily doses of at least 10 mg reduces the risk of all-cause mortality by 16% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation. The risk of mortality was reduced by 54% when children took zinc for up to one year, but overall mortality was not reduced in studies lasting at least one year (106239).
Periodontitis. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with moderate or advanced periodontitis shows that taking a combination supplement containing zinc 3.75 mg, alpha-lipoic acid, coenzyme Q10, cranberry extract, grapeseed extract, selenium, vitamin C, and vitamin E twice daily for 8 weeks in addition to standard nonsurgical therapy does not reduce periodontal indices including bleeding on probing, gingival recession, plaque index, or inflammation when compared with placebo (111708).
Pharyngitis. There is limited evidence on the oral use of zinc for reducing the risk of postoperative sore throat. Details: Clinical research shows that dissolving a lozenge containing zinc 40 mg as zinc sulfate in the mouth in the 30 minutes before surgery involving endotracheal intubation reduces the incidence of postoperative sore throat by 58% when compared with placebo lozenges. It also seems to reduce the severity of postoperative sore throat that does occur (97138).
Polycystic ovary syndrome (PCOS). It is unclear if oral zinc is beneficial in patients with PCOS. Details: A small clinical study in adults taking metformin for PCOS shows that also taking zinc sulfate 220 mg (50 mg elemental zinc) daily for 8 weeks improves hair loss and facial growth, but not acne, when compared with placebo (96071).
Postpartum depression. It is unclear if oral zinc prevents postpartum depression after a Cesarean section (C-section). Details: A small observational study in pregnant patients with anemia who underwent C-section has found that taking zinc sulfate 100 mg daily for 4 days after surgery is associated with a 75% reduction in the odds of developing postpartum depression when compared with no supplementation (109452).
Premenstrual syndrome (PMS). It is unclear if oral zinc improves symptoms in patients with PMS. Details: A small clinical study in female college students shows that taking elemental zinc 30 mg daily for 3 months improves quality of life, but not quality of sleep, when compared with placebo (104049).
Preterm labor. It is unclear if oral zinc reduces the risk of preterm labor. Details: Observational research has found that low dietary intake of zinc during pregnancy is associated with an increased likelihood of preterm deliveries (87471). Also, most meta-analyses of clinical research show that taking zinc supplements during pregnancy modestly reduces the risk of preterm birth (106231). However, one large meta-analysis of 22 clinical studies shows that zinc supplementation during pregnancy seems to have little or no benefit for reducing the risk of preterm birth when compared with control (105679). Zinc supplementation also does not seem to reduce the risk of stillbirth, neonatal death, spontaneous abortion, or premature rupture of membranes (97142,105679,106231).
Prostatitis. It is unclear if oral zinc improves symptoms in men with chronic prostatitis. Details: A clinical study in men with chronic prostatitis shows that taking zinc sulfate 220 mg daily along with prazosin 2 mg daily for 12 weeks does not improve difficulty urinating or quality of life, but does seem to improve pain, when compared with prazosin alone (90210). The validity of this study was limited by a significant dropout rate.
Pruritus. There is limited evidence on the oral use of zinc for reducing pruritis in hemodialysis patients. Details: A small clinical study in end-stage renal disease patients with hemodialysis-associated pruritus shows that taking zinc sulfate 220 mg twice daily for 2 months reduces pruritus severity when compared with placebo (90218).
Psoriatic arthritis. It is unclear if oral zinc improves psoriatic arthritis symptoms. Details: Two small clinical trials in patients with psoriatic arthritis show that taking zinc orally, alone or in combination with nonsteroidal anti-inflammatory drugs (NSAIDs), does not seem to reduce pain or improve function when compared with control (6514,6515).
Respiratory tract infections. It is unclear if oral zinc reduces respiratory tract infections in children. Details: An open-label study in children aged 6 months to 5 years with zinc deficiency shows that taking zinc sulfate 20 mg orally once daily for 2 weeks reduces the number of episodes and the mean duration of upper and lower respiratory tract infections over 6 months of follow-up when compared with the 6 months prior to zinc supplementation (104815). The validity of this finding is limited by the lack of a comparator group.
Rosacea. It is unclear of oral zinc improves symptoms of rosacea or quality of life. Details: A small clinical trial shows that taking zinc sulfate 440 mg in two divided doses daily for 90 days does not improve quality of life or symptoms associated with rosacea when compared with placebo (90195).
Seizures. It is unclear if oral zinc reduces recurrent febrile seizures in children. Details: Although some individual preliminary clinical research disagrees (96069), a meta-analysis of generally low-quality research in children under 5 years of age with a previous febrile seizure shows that taking zinc sulfate 1-2 mg/kg or 20 mg daily for 6-12 months does not reduce febrile seizure recurrence when compared with placebo (106237). Also, a small clinical study shows that taking zinc does not increase the time to first febrile seizure recurrence (96069).
Sepsis. It is unclear if oral zinc is beneficial in sepsis of the newborn. Details: A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of sepsis mortality by 57% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). Also, a small clinical study in newborns with sepsis shows that giving zinc sulfate monohydrate 3 mg/kg twice daily for 10 days along with antibiotics reduces the likelihood of neurological abnormalities, such as those related to posture, behavior, and reflexes, by 70% when compared with antibiotics alone. Mortality and length of hospital stay were not improved, but the study may have been inadequately powered to detect a difference in these parameters (96077). Another study in preterm infants with late-onset sepsis (developing at least 72 hours after birth), shows that giving 1.4 mg/kg elemental zinc daily orally for 10 days in addition to antibiotics reduces the number of infants with unresolved sepsis at 10 days, and reduces C-reactive protein and procalcitonin levels, when compared with giving antibiotics alone (104819). A meta-analysis of small clinical studies in infants less than 4 months old shows that administering zinc 1-3 mg/kg daily for 1-18 weeks may reduce the rate of infant mortality and treatment failure when compared with placebo or control, but does not seem to prevent sepsis or improve sepsis-related mortality (108444).
Shigellosis. It is unclear if oral zinc is beneficial in patients with acute shigellosis from food poisoning. Details: A small clinical study in malnourished children with acute shigellosis (food poisoning) shows that administering a multivitamin syrup containing elemental zinc 20 mg daily for 2 weeks, in addition to standard treatment, can improve recovery time and reduce the number of diarrhea episodes when compared with multivitamin syrup without elemental zinc (87088).
Substance use disorder. It is unclear if oral zinc is beneficial for substance use disorder. Details: Preliminary clinical research in adults with opioid use disorder that were being treated with methadone shows that taking zinc sulfate, containing 12 mg zinc, orally daily for 3 months moderately improves relapse prevention scores, including drug use and drug craving scores, when compared with control. Taking zinc also modestly improved stress and anxiety scores (111293).
Traumatic brain injury (TBI). There is limited evidence on the parenteral use of zinc for closed head injury. Details: A small clinical study shows that administering zinc parenterally immediately following severe closed head injury seems to improve the rate of neurological recovery when compared with standard therapy (2696).
Tuberculosis. It is unclear if oral zinc can improve outcomes in patients receiving tuberculosis treatment. Details: Low levels of zinc are common in patients with tuberculosis. In patients newly diagnosed with tuberculosis and using anti-tuberculosis treatment, some clinical research shows that taking zinc 50 mg daily as zinc sulfate for 6 months increases the number of patients with negative sputum smears by 50% to 80% within the first 6 weeks of treatment when compared with placebo. However, there were no differences in the number of patients with negative smears after this time point. There were also improvements in some liver function enzyme levels after 2 months, but not 6 months, when compared with placebo (106238). However, other clinical research shows that taking zinc 15-90 mg daily for 2-6 months does not improve cure rates or sputum smear conversions when compared with placebo. However, when combined with vitamin A, serum levels of vitamin A, zinc, and hemoglobin were modestly improved and there was a modest increase in sputum smear conversions (109754).
Urinary tract infections (UTIs). It is unclear if oral zinc is beneficial in children with UTI. Details: A low-quality, clinical study in children aged 3-12 years hospitalized for a UTI and receiving intravenous antibiotic treatment shows that taking zinc 1 mg/kg daily for 14 days reduces the duration of dysuria, urinary frequency, and urgency when compared with intravenous antibiotics alone. Zinc does not improve fever or the time to negative urine culture (96081). However, this study did not demonstrate that treatment groups were equal at baseline.
Venous leg ulcers. It is unclear if oral or topical zinc is beneficial for leg ulcer healing. Details: Two small studies in elderly patients with leg ulcers suggest that using a zinc saline solution on a wound dressing or applying zinc oxide to a dressing might improve healing of leg ulcers (2694,6901). However, oral zinc supplementation does not seem to be beneficial. A meta-analysis of four small clinical trials in patients with venous leg ulcers shows that taking zinc orally does not improve healing when compared with placebo (104079).
Vertigo. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with benign paroxysmal positional vertigo with serum 25-hydroxyvitamin D levels less than 20 ng/mL shows that taking a specific combination product containing zinc 7.5 mg, alpha-lipoic acid 600 mg, L-carnosine 165 mg, curcumin 100 mg, piperine 1 mg, cholecalciferol 800 units, vitamin B2 0.8 mg, and vitamin B6 1 mg (Vertistop D, Difass) orally daily for 6 months moderately reduces the number of vertigo relapse episodes when compared with control. However, in patients with serum 25-hydroxyvitamin D levels greater than 20 ng/mL that took a specific combination product containing zinc 7.5 mg, alanine 600 mg, L-carnosine 165 mg, curcumin 100 mg and piperine 1 mg (Vertistop L, Difass) orally daily for 6 months there was no difference in relapse episodes when compared with control (111294). It is unclear if this effect is due to zinc, other ingredients, or the combination.
Water warts. It is unclear if oral zinc is beneficial for the treatment of water warts in children. Details: In children with water warts, preliminary clinical research shows that taking zinc sulfate heptahydrate (as Zinco syrup) for 2 months results in lesion resolution in 70% of patients when compared with baseline. Lesion resolution occurred in an additional 13% of patients in the month after treatment completion, with no recurrence in any of these children over the next 9 months. Zinc 3 mg daily was used in children up to 3 years of age, and 5 mg daily was used in older children (106234). Due to the lack of a comparator group, it is unclear if these outcomes are due to zinc or the natural resolution of the condition.
Wound healing. Topical zinc might be beneficial for the healing of uncomplicated wounds. Details: A small clinical study shows that applying zinc chloride solution, standardized to contain zinc 20 mcg/mL, twice daily improves wound healing when compared with saline solution in patients with uncomplicated, skin wounds. However, when zinc is administered as a component of an insulin product (Humulin, Eli Lilly and Company), it seems to be more effective than zinc chloride alone (90192).
Wrinkled skin. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A topical preparation containing 10% vitamin C as L-ascorbic acid and acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied to photo-aged facial skin for 3 months seems to improve fine and coarse wrinkling, yellowing and sallowness, roughness, and skin tone when compared with placebo (6155). More evidence is needed to rate zinc for these uses.

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Safety view details

Below is general information about the safety of the known ingredients contained in the product NK-Stim. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe vera leaf gel extract)

LIKELY SAFE ...when aloe gel is used topically and appropriately. Aloe gel-containing formulations have been safely applied in clinical trials (101,11982,12096,12098,12159,12160,12163,12164,17418)(90123,90124,90127,90128,90129,90131,97320,98816,103305). When included in topical cosmetics, the Cosmetic Ingredient Review Expert Panel concluded that aloe-derived anthraquinone levels should not exceed 50 ppm (90122).

POSSIBLY SAFE ...when aloe gel is used orally and appropriately, short-term. Aloe gel has been safely used in a dose of 15 mL daily for up to 42 days or 100 mL of a 50% solution twice daily for up to 4 weeks (11984,12164). Also, a specific aloe gel complex (Aloe QDM complex, Univera Inc.) has been safely used at a dose of approximately 600 mg daily for up to 8 weeks (90121). ...when aloe extract is used orally and appropriately, short-term. Aloe extract has been used with apparent safety in a dose of 500 mg daily for one month (101579). Also, an aloe extract enriched in aloe sterols has been used with apparent safety in a dose of 500 mg daily for 12 weeks (101577).

POSSIBLY UNSAFE ...when aloe latex is used orally. There is some evidence that anthraquinones in aloe latex are carcinogenic or promote tumor growth, although data are conflicting (6138,16387,16388,91596,91597). In 2002, the US FDA banned the use of aloe latex in laxative products due to the lack of safety data (8229). ...when aloe whole-leaf extract is used orally. Aloe whole-leaf extract that has not been filtered over charcoal still contains anthraquinones. This type of aloe whole-leaf extract is referred to as being "nondecolorized". The International Agency for Research on Cancer has classified this type of aloe whole-leaf extract as a possible human carcinogen (91598,91908). Although filtering aloe whole-leaf extract over charcoal removes the anthraquinones, some animal research suggests that this filtered extract, which is referred to as being "decolorized", may still cause gene mutations (91598). This suggests that constituents besides anthraquinones may be responsible for the carcinogenicity of aloe whole-leaf extract. It should be noted that commercial products that contain aloe whole-leaf extract may be labeled as containing "whole leaf Aloe vera juice" or "aloe juice" (91908).

LIKELY UNSAFE ...when aloe latex is used orally in high doses. Ingesting aloe latex 1 gram daily for several days can cause nephritis, acute kidney failure, and death (8,8961).

CHILDREN: POSSIBLY SAFE
when aloe gel is used topically and appropriately. Aloe gel-containing formulations have been safely applied in clinical trials (90124,90131).

CHILDREN: POSSIBLY UNSAFE
when aloe latex and aloe whole leaf extracts are used orally in children. Children younger than 12 years may experience abdominal pain, cramps, and diarrhea (4).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Anthraquinones present in aloe latex and aloe whole leaf extracts have irritant, cathartic, and possible mutagenic effects (4,16387,16388,90122). There are also anecdotal reports and evidence from animal research that anthraquinones or aloe whole leaf extracts might induce abortion and stimulate menstruation; avoid using (4,8,19,90122).

LACTATION: POSSIBLY UNSAFE
when aloe preparations are used orally. Cathartic and mutagenic anthraquinones present in aloe latex and aloe whole leaf extracts might pass into milk; avoid using (4,19).

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LARCH ARABINOGALACTAN (Arabinogalactan Heartwood)

LIKELY SAFE ...when used orally in amounts found in foods. Larch arabinogalactan has Generally Recognized As Safe (GRAS) status in the US (3529).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts, short-term. Larch arabinogalactan has been safely used at doses of 1.5-8.4 grams daily for up to 6 months (15617,15618,17370,93102,93104,104281). Higher doses of 15-30 grams daily have been used with apparent safety for up to 6 weeks (15620). There is insufficient reliable information available about the safety of larch arabinogalactan when used long-term.

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

OLIVE (Olive leaf extract)

LIKELY SAFE ...when olive fruit is used orally and appropriately in amounts commonly found in foods.

POSSIBLY SAFE ...when olive leaf extract is used orally and appropriately. Olive leaf extract providing 51-100 mg oleuropein daily has been used with apparent safety for 6-8 weeks (92245,92247,101860). There is insufficient reliable information available about the safety of olive fruit extract when used in amounts greater than those found in foods.

PREGNANCY AND LACTATION:
Insufficient reliable information available; stick with amounts commonly found in foods.

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ZINC

LIKELY SAFE ...when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 40 mg daily (7135). ...when used topically and appropriately (2688,6538,6539,7135,8623,11051,111291).

POSSIBLY SAFE ...when used orally and appropriately in doses higher than the tolerable upper intake level (UL). Because the UL of zinc is based on regular daily intake, short-term excursions above 40 mg daily are not likely to be harmful. In fact, there is some evidence that doses of elemental zinc as high as 80 mg daily in combination with copper 2 mg can be used safely for approximately 6 years without significant adverse effects (7303,8622,92212). However, there is some concern that doses higher than the UL of 40 mg daily might decrease copper absorption and result in anemia (7135).

POSSIBLY UNSAFE ...when used intranasally. Case reports and animal research suggest that intranasal zinc might cause permanent anosmia or loss of sense of smell (11155,11156,11703,11704,11705,11706,11707,16800,16801,17083). Several hundred reports of anosmia have been submitted to the US Food and Drug Administration (FDA) and the manufacturer of some intranasal zinc products (Zicam) (16800,16801). Advise patients not to use intranasal zinc products.

LIKELY UNSAFE ...when taken orally in excessive amounts. Ingestion of 10-30 grams of zinc sulfate can be lethal in adults (7135). Chronic intake of 450-1600 mg daily can cause multiple forms of anemia, copper deficiency, and myeloneuropathies (7135,17092,17093,112473). This has been reported with use of zinc-containing denture adhesives in amounts exceeding the labeled directions, such as several times a day for several years (17092,17093). Advise patients to follow the label directions on denture adhesives that contain zinc.

CHILDREN: LIKELY SAFE
when used orally and appropriately (7135). Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL). The UL for children is based on age: 4 mg daily for 0-6 months, 5 mg daily for 7-12 months, 7 mg daily for 1-3 years, 12 mg daily for 4-8 years, 23 mg daily for 9-13 years, and 34 mg daily for 14-18 years (7135,97140).

CHILDREN: POSSIBLY UNSAFE
when used orally in high doses. Taking amounts greater than the UL can cause sideroblastic anemia and copper deficiency (7135). ...when used topically on damaged skin. An infant treated with 10% zinc oxide ointment for severe diaper rash with perianal erosions developed hyperzincemia. Absorption seemed to occur mainly via the erosions; plasma levels dropped after the erosions healed despite continued use of the ointment (106905).

PREGNANCY: LIKELY SAFE
when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 34 mg daily during pregnancy in those 14-18 years of age and 40 mg daily in those 19-50 years of age (7135).

PREGNANCY: LIKELY UNSAFE
when used orally in doses exceeding the UL (7135).

LACTATION: LIKELY SAFE
when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 34 mg daily during lactation in those 14-18 years of age, and 40 mg daily for those 19-50 years of age (7135).

LACTATION: POSSIBLY UNSAFE
when used orally in doses exceeding the UL. Higher doses can cause zinc-induced copper deficiency in nursing infants (7135).

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Interactions with Drugs view details

Below is general information about the interactions of the known ingredients contained in the product NK-Stim. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe vera leaf gel extract)

ANTICOAGULANT/ANTIPLATELET DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe gel might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.

Details

In vitro research shows that aloe gel can inhibit platelet aggregation. This inhibition was greater than that seen with celecoxib, but less than that seen with aspirin (105501).

ANTIDIABETES DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Aloe might increase the risk of hypoglycemia when taken with antidiabetes drugs.

Details

Preliminary clinical research suggests aloe gel might lower blood glucose levels (11983,12164,19756) and have additive effects when used with antidiabetes drugs. Monitor blood glucose levels closely.

DIGOXIN (Lanoxin)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Theoretically, aloe latex might increase the risk of adverse effects when taken with cardiac glycosides.

Details

Overuse of aloe latex can increase the risk of adverse effects from cardiac glycoside drugs, such as digoxin, due to potassium depletion. Overuse of aloe, along with cardiac glycoside drugs, can increase the risk of toxicity (19).

DIURETIC DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk of hypokalemia when taken with diuretic drugs.

Details

Overuse of aloe latex might compound diuretic-induced potassium loss, increasing the risk of hypokalemia (19).

STIMULANT LAXATIVES

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk for fluid and electrolyte loss when taken with stimulant laxatives.

Details

Due to cathartic laxative effects of aloe latex, concomitant use with other stimulant laxatives might compound fluid and electrolyte loss (19,19742,19743,19744).

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk of bleeding when taken with warfarin.

Details

Aloe latex has stimulant laxative effects. In some people aloe latex can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Advise patients who take warfarin not to take excessive amounts of aloe vera.

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LARCH ARABINOGALACTAN (Arabinogalactan Heartwood)

IMMUNOSUPPRESSANTS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, larch arabinogalactan might interfere with immunosuppression therapy due to immunostimulant effects (3529,3530,93103). Immunosuppressant drugs include azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), corticosteroids (glucocorticoids), and other drugs.

OLIVE (Olive leaf extract)

None known.

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ZINC

AMILORIDE (Midamor)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Probable • Level of Evidence = B

Amiloride can modestly reduce zinc excretion and increase zinc levels.

Details

Clinical research shows that amiloride can reduce urinary zinc excretion, especially at doses of 10 mg per day or more. This zinc-sparing effect can help to counteract zinc losses caused by thiazide diuretics, but it is unlikely to cause zinc toxicity at usual amiloride doses (830,11626,11627,11634). The other potassium-sparing diuretics, spironolactone (Aldactone) and triamterene (Dyrenium), do not seem to have a zinc-sparing effect.

ATAZANAVIR (Reyataz)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Probable • Level of Evidence = B

Zinc modestly reduces levels of atazanavir, although this effect does not seem to be clinically significant.

Details

Clinical research shows that zinc might decrease serum atazanavir levels by chelating with atazanavir in the gut and preventing its absorption (93578). Although a single dose of zinc sulfate (Solvazinc tablets) 125 mg orally does not affect atazanavir concentrations in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate 125 mg daily for 2 weeks reduces plasma levels of atazanavir by about 22% in these patients. However, despite this decrease, atazanavir levels still remain at high enough concentrations for the prevention of HIV virus replication (90216).

CEPHALEXIN (Keflex)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Zinc might decrease cephalexin levels by chelating with cephalexin in the gut and preventing its absorption.

Details

A pharmacokinetic study shows that zinc sulfate 250 mg taken concomitantly with cephalexin 500 mg decreases peak levels of cephalexin by 31% and reduces the exposure to cephalexin by 27%. Also, taking zinc sulfate 3 hours before cephalexin decreases peak levels of cephalexin by 11% and reduces the exposure to cephalexin by 18%. By decreasing cephalexin levels, zinc might increase the risk of treatment failure. This effect does not occur when zinc is taken 3 hours after the cephalexin dose (94163). To avoid an interaction, advise patients take zinc sulfate 3 hours after taking cephalexin.

CISPLATIN (Platinol-AQ)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, zinc might interfere with the therapeutic effects of cisplatin.

Details

Animal research suggests that zinc stimulates tumor cell production of the protein metallothionein, which binds and inactivates cisplatin (11624,11625). It is not known whether zinc supplements or high dietary zinc intake can cause clinically significant interference with cisplatin therapy. Cisplatin might also increase zinc excretion.

INTEGRASE INHIBITORS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, taking zinc along with integrase inhibitors might decrease the levels and clinical effects of these drugs.

Details

Zinc is a divalent cation. Pharmacokinetic studies have shown that other divalent cations such as calcium and iron can decrease blood levels of the integrase inhibitor dolutegravir through chelation (93578,93579).

PENICILLAMINE (Cuprimine, Depen)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Zinc might reduce the levels and clinical effects of penicillamine.

Details

By forming an insoluble complex with penicillamine, zinc interferes with penicillamine absorption and activity. Zinc supplements reduce the efficacy of low-dose penicillamine (0.5-1 gram/day), but do not seem to affect higher doses (1-2.75 gram/day), provided dosing times are separated (2678,4534,11605). Advise patients to take zinc and penicillamine at least 2 hours apart.

QUINOLONE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Zinc can decrease the levels and clinical effects of quinolones antibiotics.

Details

Quinolones form complexes with zinc in the gastrointestinal tract, reducing absorption of both the quinolone and zinc if taken at the same time (828,2682,3046,11600). Advise patients to take these drugs at least 2 hours before, or 4-6 hours after, zinc supplements.

RITONAVIR (Norvir)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Probable • Level of Evidence = B

Zinc modestly reduces levels of ritonavir.

Details

Clinical research shows that zinc might reduce serum ritonavir levels by chelating with ritonavir in the gut and preventing its absorption (93578). In patients with HIV, ritonavir is taken with atazanavir to prevent the metabolism and increase the effects of atazanavir. A pharmacokinetic study shows that, in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate (Solvazinc tablets) 125 mg as a single dose or as multiple daily doses for 2 weeks reduces plasma levels of ritonavir by about 16% (90216). However, atazanavir levels still remains high enough to prevent HIV virus replication. Therefore, the decrease in ritonavir levels is not likely to be clinically significant.

TETRACYCLINE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Zinc might reduce levels of tetracycline antibiotics.

Details

Tetracyclines form complexes with zinc in the gastrointestinal tract, which can reduce absorption of both the tetracycline and zinc when taken at the same time (3046,4945). Taking zinc sulfate 200 mg with tetracycline reduces absorption of the antibiotic by 30% to 40% (11615). Demeclocycline and minocycline cause a similar interaction (4945). However, doxycycline does not seem to interact significantly with zinc (11615). Advise patients to take tetracyclines at least 2 hours before, or 4-6 hours after, zinc supplements to avoid any interactions.

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Adverse Effects view details

Report an Adverse Reaction to NK-Stim

Below is general information about the adverse effects of the known ingredients contained in the product NK-Stim. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe vera leaf gel extract)

General ...Orally and topically, aloe products are generally well tolerated when used in typical doses. However, oral aloe latex is associated with a greater risk of adverse effects, especially when used in high doses or long-term.
Most Common Adverse Effects:
Orally: Aloe latex may cause abdominal pain, cramps, and diarrhea.
Topically: Burning, erythema, and itching. Contact dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Aloe latex is associated with serious adverse effects when taken in high doses or long-term. Cases of acute hepatitis due to a hypersensitivity reaction to aloe leaf extract has been reported.

Dermatologic ...Topically, aloe gel has occasionally been associated with burning (12164,19741,30697,30706), itching (12164,19741,30697), eczema (90122), erythema (19748,30706,90123), contact dermatitis (12163,12164,30695,30736,30737,30738,30740), popular eruption (30732), and urticaria (30712). Also, a case of generalized nummular and popular dermatitis attributed to hypersensitivity has been reported for a 47-year-old male who used aloe leaf gel, both topically and orally, for 4 years (30740).

Endocrine ...A case of severe hypokalemia has been reported for a male breast cancer patient who was undergoing chemotherapy and using aloe vera 1 liter daily orally for 2 weeks. The hypokalemia was attributed to the cathartic effects of aloe and resolved once aloe use was discontinued (30704).

Gastrointestinal ...Orally, aloe latex can cause abdominal pain and cramps. Long-term use or abuse of aloe latex can cause diarrhea, sometimes with hypokalemia, albuminuria, hematuria, muscle weakness, weight loss, arrhythmia, and pseudomelanosis coli (pigment spots in intestinal mucosa). Pseudomelanosis coli is believed to be harmless, and usually reverses with discontinuation of aloe. It is not directly associated with an increased risk of developing colorectal adenoma or carcinoma (6138). Orally, aloe gel may cause nausea, stomach cramps, and other gastrointestinal complaints in some patients (104174,111921,111663).
Topically, applying aloe gel in the mouth may cause nausea within 5 minutes of application in some patients (90124).

Hematologic ...A case of Henoch-Schonlein purpura, characterized by abdominal pain, purpura, and severe arthralgia, has been reported in a 52-year-old male who drank aloe juice prepared from four to five leaflets for 10 days prior to symptom development (91598).

Hepatic ...Cases of acute hepatitis have been reported after ingestion of aloe leaf extracts for between 3 weeks and 5 years. This is thought to be a hypersensitivity reaction (15567,15569,16386,17419,90126,91598). A case of acute hepatitis has also been reported for a 45-year-old female who drank two ounces of Euforia juice (Nuverus International), a product containing green tea, noni, goji, and aloe, daily for one month (90125). However, one small clinical trial in healthy individuals shows that taking aloe gel 2 ounces twice daily for 60 days does not impair liver function (104174).

Renal ...Orally, aloe latex can cause hemorrhagic gastritis, nephritis, and acute kidney failure following prolonged use of high doses (1 gram daily or more) (8961).

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LARCH ARABINOGALACTAN (Arabinogalactan Heartwood)

General ...Orally, larch arabinogalactan is generally well tolerated (3530,17370,93102). Some people can experience bloating and flatulence (3530).

Gastrointestinal ...Orally, larch arabinogalactan can cause bloating and flatulence (3530).

OLIVE (Olive leaf extract)

General ...Orally, olive fruit is well tolerated when used in typical food amounts. Olive leaf extract seems to be well tolerated.
Most Common Adverse Effects:
Orally: Headache and stomach discomfort.

Dermatologic ...Orally, one patient in one clinical trial reported bad skin and acne after using olive leaf extract (101860).

Gastrointestinal ...Orally, three patients in one clinical trial reported stomach ache after using olive leaf extract (101860).

Neurologic/CNS ...Orally, three patients in one clinical trial reported headache after using olive leaf extract (101860).

Psychiatric ...In one case report, a 67-year-old female experienced irritability, anger, a lack of control, and feelings of sadness and negativity after consuming a multi-ingredient product containing olive leaf extract 5 grams, horseradish root, and eyebright daily for 38 days. All psychiatric symptoms disappeared within days of stopping the combined product. It is hypothesized that the hydroxytyrosol component of olive leaf extract contributed to these symptoms due to its chemical similarity to dopamine; however, it is not clear if these symptoms were due to the olive leaf extract or to the other ingredients (96245).

Pulmonary/Respiratory ...Olive tree pollen can cause seasonal respiratory allergy (1543).

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ZINC

General ...Orally, zinc is well tolerated in doses below the tolerable upper intake level (UL), which is 40 mg daily for adults. Topically, zinc is well tolerated.
Most Common Adverse Effects:
Orally: Abdominal cramps, diarrhea, metallic taste, nausea and vomiting (dose-related).
Topically: Burning, discoloration, itching, stinging, and tingling when applied to irritated tissue.
Intranasally: Bad taste, dry mouth, headache, irritation, reduced sense of smell.
Serious Adverse Effects (Rare):
Orally: There have been cases of acute renal tubular necrosis, interstitial nephritis, neurological complications, severe vomiting, and sideroblastic anemia after zinc overdose.
Intranasally: There have been cases where intranasal zinc caused permanent loss of smell (anosmia).

Dermatologic ...Topically, zinc can cause burning, stinging, itching, and tingling when applied to inflamed tissue (6911,8623,87297). Zinc oxide can be deposited in the submucosal tissue and cause dark discoloration of the skin. This can occur with prolonged topical application to intact skin, application to eroded or ulcerated skin, or penetrating traumatic exposure, and also parenteral administration (8618).
In rare cases, oral zinc has resulted in worsened acne (104056), skin sensitivity (6592), a leishmanial reaction with a macular rash that occurred on exposed parts of the body (86935), eczema (104055), systemic contact dermatitis (109457), and the development of severe seborrheic dermatitis (86946).

Gastrointestinal ...Orally, zinc can cause nausea (338,2663,2681,6592,6700,18216,106230,106233,106227), vomiting (2663,2681,6519,6592,96069,96074), a metallic or objectionable taste in the mouth (336,338,6700,11350,18216,106902), abdominal cramping (6592,96069), indigestion (87227), heartburn (96069), dry mouth (87533), and mouth irritation (336,2619). When used orally in amounts above the tolerable upper intake level, zinc may cause irritation and corrosion of the gastrointestinal tract (331,86982,87315,106902), watery diarrhea (1352), epigastric pain (2663,2681), and severe vomiting (2663,2681).
Intranasally, zinc can cause bad taste, dry mouth, and burning and irritation of the throat (8628,8629).
When used topically as a mouth rinse, zinc may cause tooth staining (90206).

Hematologic ...There is concern that high daily doses of zinc, above the tolerable upper intake level (UL) of 40 mg per day, might increase the risk of copper deficiency, potentially leading to anemia and leukopenia (7135,112473). To prevent copper deficiency, some clinicians give a small dose of copper when zinc is used in high doses, long-term (7303).

Hepatic ...There are two cases of liver deterioration in patients with Wilson disease following initiation of treatment with zinc 50-200 mg three times daily. The mechanism of action is not understood, and the event is extremely uncommon (86927,87470).

Immunologic ...Daily doses of 300 mg of supplemental zinc for 6 weeks appear to impair immune response (7135). A case of erythematosus-like syndrome, including symptoms such as fever, leg ulcers, and rash, has been reported following intake of effervescent tablets (Solvezink) containing zinc 45 mg (87506). In another case, severe neutropenia was reported after taking supplemental zinc 900 mg daily for an unknown duration (112473).

Neurologic/CNS ...Zinc-containing denture adhesives can cause toxicity if used more frequently than recommended for several years. Case reports describe hyperzincemia, low copper levels, blood dyscrasias, and neurological problems, including sensory disturbances, numbness, tingling, limb weakness, and difficulty walking in patients applying denture adhesive multiple times daily for several years (17092,17093,90205,90233). Due to reports of zinc toxicity associated with use of excessive amounts of zinc-containing denture adhesives for several years, GlaxoSmithKline has reformulated Polygrip products to remove their zinc content (17092,17093).
Intranasally (8628) and orally (87534), zinc can cause headache. When used orally in amounts above the tolerable upper intake level (UL), zinc may cause central nervous system (CNS) symptoms including lethargy, fatigue, neuropathy, dizziness, and paresthesia (2663,2681,87369,87470,87533,87534,112473).

Oncologic ...There is concern that zinc might worsen prostate disease. For example, some preliminary evidence suggests that higher dietary zinc intake increases the risk for benign prostatic hyperplasia (6908). Epidemiological evidence suggests that taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer (10306). Another large-scale population study also suggests that men who take a multivitamin more than 7 times per week and who also take a separate zinc supplement have a significantly increased risk of prostate cancer-related mortality (15607). However, a large analysis of population research suggests that there is no association between zinc intake and the risk of prostate cancer (96075).

Pulmonary/Respiratory ...There are several hundred reports of complete loss of sense of smell (anosmia) that may be permanent with use of zinc gluconate nasal gel, such as Zicam (11306,11155,11707,16800,16801,17083,86999,87535). Loss of sense of smell is thought to be dose related but has also been reported following a single application (11306,11155,11707,16800). Patients often report having sniffed deeply when applying the gel, then experiencing an immediate burning sensation, and noticing anosmia within 48 hours (17083). On June 16, 2009, the US Food and Drug Administration (FDA) advised patients not to use a specific line of commercial zinc nasal products (Zicam) after receiving 130 reports of loss of smell (16800). The manufacturer of these products had also received several hundred reports of loss of smell related to its intranasal zinc products (16801). Zinc sulfate nasal spray was used unsuccessfully for polio prophylaxis before the polio vaccine was developed. It caused loss of smell and/or taste, which was sometimes permanent (11713). Animal studies suggest that zinc sulfate negatively affects smell, possibly by damaging the olfactory epithelium and neurons (11156,11703,11704,11705,11706). Zinc gluconate nasal spray has not been tested for safety in animals or humans. The clinical studies of intranasal zinc have not described anosmia as an adverse effect, but testing was not done to see if zinc use adversely affected sense of smell (6471,8628,8629,10247). Also, these clinical studies reported tingling or burning sensation in the nostril, dry nose, nose pain, and nosebleeds.
When used in amounts above the tolerable upper intake level (UL), zinc may cause flu-like symptoms including coughing (2663).

Renal ...In overdose, zinc can cause acute renal tubular necrosis and interstitial nephritis (331,1352,87338).

Other ...Occupational inhalation of zinc oxide fumes can cause metal fume fever with symptoms including fatigue, chills, fever, myalgias, cough, dyspnea, leukocytosis, thirst, metallic taste, and salivation (331).

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