Quercetin Phytosome by Absonutrix

POSSIBLY INEFFECTIVE

• Athletic performance. Oral quercetin does not seem to improve athletic performance. Details: A pooled analysis of data from seven clinical trials shows that intake of quercetin does not improve maximal oxygen consumption or capacity to perform prolonged exercise in trained or untrained athletes when compared with placebo (91577). Additionally, one small clinical study in male soldiers shows that taking quercetin 500 mg twice daily for 8.5 days before a loaded treadmill marching test and a cycling time trial test does not affect ratings of perceived exertion, cycling time, or peak oxygen consumption during treadmill testing when compared with placebo (91578). Quercetin has also been evaluated in combination with another ingredient. A small clinical study in trained athletes shows that taking a single dose of quercetin (Quercetin Powder from Sophora Japonica Flower, Aki Organics) 140 mg and mangiferin 84 mg, a mango constituent, one hour prior to an intermittent high-intensity exercise test improves performance as measured by circuit time and reduces perceived exertion, but does not improve heart rate, sprint time, or subjective muscle soreness when compared with placebo (113077). It is unclear whether these effects are due to quercetin, mangiferin, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral quercetin is beneficial in older adults with age-related cognitive decline. Details: Preliminary research in healthy adults aged 60 to 80 years with age-related forgetfulness shows that drinking 500 mL of a barley-based beverage containing 110 mg quercetin glycoside calculated as isoquercitrin, daily for 40 weeks seems to improve reaction times when compared with placebo. However, increase in score on the mini-mental state examination (MMSE), reduction in accumulation of amyloid beta in the brain, and prevention of reduction in cerebral blood flow occur to a similar extent with quercetin and placebo (110008).
• Allergic rhinitis (hay fever). It is unclear if oral quercetin is beneficial in patients with allergic rhinitis. Details: A small clinical study in Japanese adults with allergic rhinitis shows that taking a specific quercetin product (Quercetin Phytosome, Indena SpA) 100 mg twice daily for 4 weeks does not improve scores related to quality of life, activities of daily living, nasal symptoms, or ocular symptoms on the Japanese Rhino-conjunctivitis Quality of Life Questionnaire (JRQLQ). However, scores related to fatigue and sleep quality improved when compared with placebo. Additionally, sneezing, rhinorrhea, and activities of daily living scores improved when another scale was used to assess the severity of allergic rhinitis (109620). Quercetin has also been evaluated in combination with other ingredients. A small clinical study in children aged 6-12 years with allergic rhinitis who had gone through a treatment phase with antihistamines and a specific combination of quercetin, perilla, and vitamin D3 (Lertal) 1 tablet daily for 4 weeks shows that taking this specific combination for an additional 4-12 weeks reduces the chance of having symptom exacerbations by approximately 50% when compared with no further treatment past the first 4 weeks. The number of days requiring rescue medication was also reduced from 28.5 days to an average of 9.6 days (104676).
• Alzheimer disease. Although there has been interest in using oral quercetin for Alzheimer disease, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Asthma. It is unclear if oral quercetin is beneficial in patients with asthma. Details: Preliminary clinical research in patients with mild-to-moderate asthma shows that taking a specific quercetin product (QFit, Indena SpA) 250 mg or 500 mg daily for 30 days along with conventional therapy reduces daytime and nighttime asthma symptoms, improves spirometry measures, and decreases the use of rescue inhalers when compared to baseline. Significant improvements in these outcomes were lacking in patients receiving conventional therapy alone (102540).
• Atherosclerosis. Although there has been interest in using oral quercetin for atherosclerosis, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Autism spectrum disorder. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in children aged 4-10 years with autism shows that taking a combination of luteolin 10 mg/kg, quercetin 7 mg/kg, and rutin 3 mg/kg in olive oil for 26 weeks improves hyperactivity, irritability, and lethargy by a moderate to large amount, and improves some indices of functioning, such as daily living and social behavior, by a small amount when compared with baseline. The validity of these findings is limited by the lack of a comparator group (96765).
• Benign prostatic hyperplasia (BPH). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking one tablet of a specific combination product (Difaprost) containing quercetin, beta-sitosterol, and saw palmetto daily for 3 months does not improve general symptoms of BPH when compared to baseline (96784). The validity of these findings is limited by the lack of a comparator group.
• Beta-thalassemia. It is unclear if oral quercetin is beneficial in patients with beta-thalassemia. Details: Preliminary clinical research in transfusion-dependent patients with beta-thalassemia shows that taking quercetin 500 mg daily for 12 weeks reduces iron and ferritin levels, increases transferrin levels, and decreases transferrin saturation when compared with placebo. However, total iron binding capacity was not improved. These results suggest that quercetin might reduce iron overload, which is a complication of frequent blood transfusions in these patients (102541).
• Cancer. Although there has been interest in using intravenous or intraperitoneal quercetin for cancer, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Canker sores. Topical quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a cream containing quercetin, glycol, zinc, and Myristica (Rootage skin cream, Elsi-Si) three times daily results in complete healing of minor canker sores and reduces pain in 100% of patients within 7-10 days, compared with only 60% of patients using a benzydamine hydrochloride mouthwash three times daily (104677).
• Cardiovascular disease (CVD). It is unclear if oral quercetin is beneficial for CVD prevention. Details: Population research has found that increasing dietary intake of quercetin from food sources such as tea, onions, and apples is associated with a significantly reduced risk of heart disease-related mortality in elderly males (7726). However, preliminary clinical research shows that quercetin 1 gram daily for 28 days does not significantly improve platelet aggregation, thromboxane B2 production, blood pressure, heart rate, or serum lipid levels when compared with placebo in healthy people (1998).
• Cataracts. Although there has been interest in using oral quercetin for cataracts, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Chemotherapy-induced cystitis. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with bladder cancer undergoing intravesical chemotherapy shows that taking a specific combination product (Ialuril, IBSA Farmaceutici) containing quercetin 400 mg, hyaluronic acid 40 mg, chondroitin sulfate 400 mg, and curcumin 400 mg every morning, starting 7 days before the first instillation and ending 30 days after the last instillation, improves lower urinary tract symptoms as measured using a visual analog scale and the International Prostate Symptom Score (IPSS) at 13 months when compared with placebo (109622).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral quercetin for CFS, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Chronic venous insufficiency (CVI). Although there has been interest in using oral quercetin for CVI, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Colorectal cancer. Although there has been interest in using oral quercetin for colorectal cancer prevention, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Contrast induced nephropathy. It is unclear if oral quercetin is beneficial for the prevention of contrast induced nephropathy. Details: Preliminary clinical research in patients undergoing coronary catheterization shows that taking quercetin 500 mg every 8 hours, starting two days prior to contrast imaging and continuing for two days after, does not appear to prevent contrast induced nephropathy when compared with a control group not receiving quercetin (102539). Given its small size, this study may have been inadequately powered to detect significant differences for this outcome.
• Coronavirus disease 2019 (COVID-19). Analysis of several small, open-label clinical studies suggest that oral quercetin may modestly reduce hospitalizations and intensive care unit (ICU) admissions in patients with COVID-19. Whether quercetin is beneficial in patients with severe COVID-19 is unclear. Details: A meta-analysis of 6 open-label clinical studies in patients with COVID-19 shows that taking quercetin 260-1000 mg daily for 7-30 days along with standard therapy with analgesics, antipyretics, antibiotics, remdesivir, or favipiravir reduces the odds of intensive care unit (ICU) admission by 69% and the odds of hospitalization by 75% but does not decrease the rate of all-cause mortality or the rate of recovery upon follow-up when compared with standard care (111412). However, the interpretation of these findings is limited by differences in the severity of COVID-19, doses and durations of quercetin therapy, and standard of care regimens used across the included studies. In outpatients in the early stages of COVID-19, two small, open-label clinical studies included in the meta-analysis above show that taking quercetin 200 mg two or three times daily for 14-30 days along with standard care reduces time to symptom resolution when compared with standard care alone. However, these studies show mixed results with respect to prevention of hospitalization, ICU admission, and death (106498,106499). More recent research in patients with early-stage, mild to moderate COVID-19 symptoms shows that taking quercetin 500 mg three times daily for 1 week, followed by 500 mg twice daily for 1 week, increases the rate of symptom resolution and achieving a negative COVID-19 test at 1 week by 116% and 183%, respectively, when compared with placebo (110009). Quercetin has also been evaluated in patients with severe COVID-19. A small, open-label clinical study of patients with severe COVID-19 who have not been admitted to the ICU shows that taking quercetin 500 mg twice daily for 7 days along with remdesivir or favipiravir shortens the time to discharge by around 1.5 days and improves symptoms of weakness and lethargy, but does not improve other symptoms of COVID-19 or reduce the risk of ICU admission or death, when compared with remdesivir or favipiravir alone (107450).
• Depression. It is unclear if oral quercetin is beneficial for depression in patients with a recent myocardial infarction (MI). Details: A moderate-sized clinical study in adults 6-8 weeks post-MI conducted in Iran shows that taking quercetin 500 mg daily for 8 weeks does not improve self-reported depression scores when compared with placebo (112228). However, the severity of patients' depression was minimal at baseline, which limits the power to detect a difference between groups.
• Diabetes. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with type 2 diabetes who are not using hypoglycemic agents shows that taking a specific combination of quercetin, myricetin, and chlorogenic acid (Emulin, Anderson Global Group LLC) 250 mg daily for 7 days reduces levels of fasting and postprandial glucose by about 5% when compared to baseline. These changes were significantly different than the slight increases seen in the placebo group. In patients taking metformin along with the combination supplement, fasting blood glucose levels decreased by about 20%, compared with a decrease of less than 1% with metformin alone (96779).
• Exercise-induced muscle damage. It is unclear if oral quercetin is beneficial for preventing muscle damage associated with exercise. Details: Some clinical research shows that taking quercetin 500 mg twice daily for 3 weeks prior to and during an endurance run or cycling event does not attenuate exercise-induced muscle damage, soreness, or inflammation (16429,16431). However, a series of two small clinical trials show that taking quercetin 1000 mg daily for 14 days prior to eccentric exercise modestly attenuates the decline in the maximal intensity of a contraction when compared with placebo (99236,104226). Additionally, this dosing regimen appears to modestly accelerate the recovery of muscle strength and neuromuscular function after exercise when compared with placebo (104226).
• Exercise-induced respiratory infections. It is unclear if oral quercetin is beneficial for prevention of respiratory infections induced by exercise. Details: Preliminary clinical research shows that taking quercetin 500 mg twice daily for 3 weeks before, and continuing during 3 days of prolonged, intense cycling, reduces the incidence of upper respiratory infections in the 14 days following the heavy exercise (16430).
• Gout. Although there has been interest in using oral quercetin for gout, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Herpes labialis (cold sores). Although there has been interest in using oral quercetin for herpes labialis, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Hypercholesterolemia. It is unclear if oral quercetin is beneficial for improving cholesterol levels. Details: Multiple meta-analyses show that taking quercetin does not affect total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or triglycerides (TG) when compared with placebo (96783,104229). However, a subgroup analysis shows that taking quercetin for at least 8 weeks seems to reduce TG levels by 13 mg/dL and increase HDL levels by 3 mg/dL, compared with no change in patients who took quercetin for less than 8 weeks (104229). It is unclear these patients had elevated cholesterol levels at baseline.
• Hypertension. It is unclear if oral quercetin is beneficial for reducing blood pressure. Details: Three meta-analyses show that taking quercetin 100-1000 mg daily for 4-12 weeks decreases systolic and diastolic blood pressure by 2-4 mmHg and 2-3 mmHg, respectively, when compared with placebo. However, only two of the studies included in these analyses evaluated patients with hypertension (16424,96775,104229,109617). Additional clinical research in patients with mild hypertension shows that taking a single dose of quercetin 1095 mg can lower systolic and diastolic blood pressure by 7 mmHg and 3 mmHg, respectively, when measured 10 hours later (96780). Overall, the benefit of quercetin on blood pressure seems modest; it is unclear whether the improvement is clinically significant for patients with hypertension.
• Kidney transplant. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that a specific product containing a combination of quercetin 20 mg and curcumin 480 mg (Oxy-Q, Farr Labs) taken once or twice daily in combination with anti-rejection medications, starting within 24 hours of a kidney transplant and continuing for one month, improves early function of the graft and reduces serum creatinine when compared with taking placebo in combination with anti-rejection medications (16420).
• Lung cancer. It is unclear if oral quercetin is beneficial in lung cancer prevention. Details: Epidemiologic research has found that increasing dietary intake of quercetin is associated with a reduced risk of lung cancer in smokers (96778).
• Metabolic syndrome. It is unclear if oral quercetin is beneficial in patients with metabolic syndrome. Details: A meta-analysis of small clinical studies shows that taking quercetin 100-1000 mg daily for 4-12 weeks does not improve fasting blood glucose, glycated hemoglobin, or insulin levels when compared with placebo in patients with risk factors for metabolic syndrome, such as type 2 diabetes, prehypertension, polycystic ovary syndrome, and/or obesity (100967). Additional research is needed to determine if quercetin is beneficial in patients with existing metabolic syndrome.
• Niacin-induced flushing. Although there has been interest in using oral quercetin for niacin-induced flushing, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Obesity. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking quercetin 500 or 1000 mg daily for 12 weeks, in addition to niacin 5 mg or 10 mg and vitamin C 125 mg or 250 mg, does not reduce body weight or fat mass when compared with placebo in adults considered overweight or obese based on body mass index (BMI) (104678).
• Oral mucositis. It is unclear if oral quercetin is beneficial in patients with oral mucositis. Details: One small clinical study shows that taking quercetin 250 mg twice daily for 4 weeks does not prevent oral mucositis associated with chemotherapy when compared with placebo (96776).
• Ovarian cancer. It is unclear if oral quercetin is beneficial for ovarian cancer prevention. Details: One epidemiologic study found no association between dietary intake of quercetin and related flavonols and the risk of ovarian cancer (16428).
• Pancreatic cancer. It is unclear if oral quercetin is beneficial for pancreatic cancer prevention. Details: Epidemiologic studies have found that a high dietary intake of quercetin and related flavonols might reduce the risk of pancreatic cancer, especially in male smokers (16426,16427).
• Peptic ulcers. Although there has been interest in using oral quercetin for peptic ulcers, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Physical performance. It is unclear if oral quercetin is effective for improving physical performance in older adults. Details: A small clinical study in Japanese individuals 50-74 years of age shows that taking quercetin glycosides 200 mg or 500 mg daily along with low-intensity resistance training 3 days weekly for 24 weeks does not improve muscle size or lean body mass, but may reduce muscle stiffness, when compared with placebo (109621).
• Polycystic ovary syndrome (PCOS). It is unclear if oral quercetin is beneficial for improving hormone levels or pregnancy rates in patients with PCOS. Details: Clinical research in patients with PCOS shows that taking quercetin 1000 mg daily for 12 weeks reduces testosterone and luteinizing hormone (LH) levels by 9% and 3%, respectively, when compared to baseline; both of these improvements were significant when compared with placebo. Insulin resistance also improved by 18% when compared to baseline, which was significant when compared with placebo (96782). In a similar group of patients with higher levels of insulin resistance at baseline, taking the same dose of quercetin modestly reduced testosterone and LH levels when compared with placebo; however, there was no improvement in insulin resistance (99237). These disparate outcomes might be due to different baseline levels of insulin resistance. Also, it is unclear if these changes are associated with an improvement in the clinical symptoms of PCOS. Quercetin has also been evaluated for improving pregnancy rates in adults with PCOS and infertility. A small clinical study shows that taking quercetin 500 mg daily for 40 days increases pregnancy rates when compared with placebo. Quercetin supplementation also improves the grading of oocytes, but not the quality of embryos, in those undergoing in vitro fertilization (IVF). Nearly 84% of patients taking quercetin became pregnant spontaneously or via IVF in the 6 months following initiation of quercetin supplementation. Only 11% of patients taking placebo became pregnant during the study, all through IVF (109618). Due to a short duration of follow-up, it is unclear whether quercetin improves live birth rates.
• Prostatitis. It is unclear if oral quercetin is beneficial in patients with prostatitis. Details: Preliminary clinical research shows that taking quercetin 500 mg twice daily for one month reduces pain and improves quality of life, but does not seem to affect voiding dysfunction, in patients with chronic, nonbacterial prostatitis when compared with placebo (481).
• Rheumatoid arthritis (RA). It is unclear if oral quercetin is beneficial in patients with RA. Details: In patients with RA, clinical research shows that taking quercetin 500 mg daily for 8 weeks improves morning stiffness, morning pain, and after-activity pain when compared with placebo. However, taking quercetin does not seem to improve the number of swollen or tender joints or the disease activity score when compared with placebo (96774).
• Schizophrenia. Although there has been interest in using oral quercetin for schizophrenia, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Upper respiratory tract infection (URTI). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking quercetin 500 mg or 1000 mg daily for 12 weeks, in combination with vitamin C 500 mg or 1000 mg daily or niacin 20 mg or 40 mg daily, does not reduce the frequency or severity of URTIs. However, in a subgroup analysis of physically fit individuals 40 years and older, the severity of URTIs and the number of sick days related to URTIs were reduced by 36% and 31%, respectively, when quercetin 1000 mg was compared with placebo (104679).
• Urethral syndrome. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking one tablet daily of a specific formulation containing quercetin, bromelain, chondroitin sulfate, gotu kola, rhodiola, and barbed skullcap (Cistiquer, Deakos) for 7 weeks reduces urinary urgency by 91% when compared with baseline. Also, 55% of patients reported no discomfort associated with urination. This combination product was reported to be at least as effective as intravesical administration of betamethasone 8 mg plus gentamicin 80 mg twice weekly (96777).
• Urinary tract infections (UTIs). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking 1-2 capsules of a combination of hyaluronic acid, chondroitin sulfate, curcumin, and quercetin daily for 15 days each month, in combination with the use of local topical estrogen therapy (0.005% estriol vaginal gel) for up to 12 months, increases the number of women cured of recurrent UTIs to 66%, compared with only 34% of those taking the oral combination product or the vaginal estrogen product alone (96781). More evidence is needed to rate quercetin for these uses.

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POSSIBLY EFFECTIVE

• Coronary heart disease (CHD). The U.S. Food and Drug Administration (FDA) allows a qualified health claim stating that using high-oleic acid sunflower oil as a replacement for other dietary fats and oils higher in saturated fat may reduce the risk of CHD. Details: A meta-analysis of clinical studies shows that replacing 7.5% of energy from partially hydrogenated vegetable oils with high-oleic acid sunflower oil can reduce CHD risk by about 9% to 19%. Furthermore, analysis of results from observational studies found that replacing partially hydrogenated oil with high-oleic acid sunflower oil is associated with a 16% to 35% reduction in the risk of CHD events (95745). The FDA allows for a qualified health claim that replacing dietary fats and oils higher in saturated fat with high-oleic acid sunflower oil may reduce the risk of CHD. To achieve this benefit, the use of high-oleic acid sunflower oil should not increase total daily energy intake. The suggested daily dietary intake is about 20 grams (1.5 tbsp) of high-oleic sunflower oil in place of other fats and oils (98563). Sunflower oil that contains high amounts of linoleic acid rather than oleic acid does not appear to improve cholesterol levels or reduce the risk of cardiovascular events in patients with CHD (96205).
• Hypercholesterolemia. Consuming sunflower oil in the diet may reduce low-density lipoprotein (LDL) cholesterol levels in some patients. Details: There is evidence that using sunflower oil in the diet as 45-50 grams daily for up to 12 weeks is more effective than olive oil for decreasing LDL cholesterol and apolipoprotein B levels in healthy individuals (9780). Also, clinical research in patients with mild hyperlipidemia or moderate hypercholesterolemia shows that consuming specific brands of mid-oleic acid (NuSun) or high-oleic acid (Sunola, Meadow Lea Foods) sunflower oils as 15% to 20% of dietary calories for up to 5 weeks is more effective than olive oil or saturated fat for decreasing total cholesterol, LDL cholesterol, and apolipoprotein B levels (76697,76698). Also, consuming a high-oleic sunflower oil-rich diet for 3 weeks decreases total cholesterol levels to a greater extent than diets enriched with palm oil or medium-chain triglycerides in patients with mild hypercholesterolemia (67569). Other preliminary clinical research in patients with moderate hypercholesterolemia shows that consuming a diet rich in sunflower oil for 3 weeks decreases total cholesterol and LDL cholesterol levels when compared with baseline. However, levels of high-density lipoprotein (HDL) cholesterol appear to be lowered as well (76714). Despite these beneficial effects, sunflower oil might be less effective than some other dietary oils. Taking sunflower oil for 3 months appears to be less effective than rice bran oil for lowering cholesterol in patients with hypercholesterolemia (76699). Also, while consuming sunflower oil 45 grams daily, as part of the diet and as a supplement, for 12 weeks reduces levels of total cholesterol and LDL cholesterol when compared to baseline, it appears to be less effective at reducing total cholesterol levels than flaxseed oil in certain patients at risk for atherosclerosis (76696). In addition, taking sunflower oil 15.1 grams daily for 4 months does not appear to reduce levels of total or LDL cholesterol in patients with peripheral vascular disease (76691).

POSSIBLY INEFFECTIVE

• Hypertension. Oral sunflower oil does not seem to lower blood pressure. Details: Preliminary clinical research in adults with hypertension shows that taking sunflower oil 30-40 grams daily for one year is less effective than extra-virgin olive oil for reducing blood pressure (5091). Also, clinical research in elderly adults with hypertension shows that taking 60 grams of sunflower oil daily for 4 weeks is less effective than virgin olive oil for reducing systolic blood pressure (76692).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Atherosclerosis. It is unclear if oral sunflower oil is beneficial for atherosclerosis; some clinical research suggests that it may provide less benefit than other dietary oils. Details: Some preliminary clinical research in individuals with overweight and obesity shows that taking sunflower oil 30 mL (about 27 grams) daily for 90 days decreases carotid intima-media thickness (CIMT) by 3.5% when compared to baseline, but not when compared with olive oil or flaxseed oil. Sunflower oil also improves flow-mediated vasodilation by 73% when compared to baseline, compared with no improvement in those taking flaxseed oil or olive oil (99303). Other preliminary clinical research in individuals waiting for carotid endarterectomy shows that taking sunflower oil 6 grams daily for up to 189 days is less effective than the same dose of fish oil, and equivalent to control oil, for improving the status of atherosclerotic plaques (76688).
• Atopic dermatitis (eczema). Although there is interest in using topical sunflower oil for atopic dermatitis, there is insufficient reliable information about the clinical effects of sunflower oil for this condition.
• Child growth. It is unclear if topical sunflower oil is beneficial for early child growth. Details: A large preliminary clinical trial in newborn infants in India shows that exclusive topical application of 10 mL of high-linoleic acid sunflower oil, an average of 2.7 times daily for about one month, increases weight gain by 1.3 gram/kg daily when compared with a control group exclusively given traditional vigorous massage with mustard oil an average of 2.4 times daily. The increase in weight gain was highest for infants weighing less than 1500-2000 grams at birth (108141). However, it is unclear if any beneficial effects are due to the sunflower oil, the massage, their combination, or the lack of mustard oil.
• Dry mouth. It is unclear if rinsing the mouth with sunflower oil is beneficial for dry mouth. Details: Preliminary clinical research in adults with moderate dry mouth associated with medication use shows that using a sunflower oil mouth rinse and gargling for 5-8 minutes before spitting it out twice daily for 7 days improves dry mouth scores by 23% when compared to baseline. Sunflower oil also improves the ability to swallow and sleep with dry mouth, but not other dry mouth symptoms or saliva flow rate, when compared with control (105523). This study may have been inadequately powered to detect a difference between groups.
• Dry skin. It is unclear if topical sunflower oil is beneficial for dry skin in infants. Details: Preliminary clinical research in full-term, newborn infants shows that topical application of 4 drops of sunflower oil to each of three parts of the body twice daily for 4 weeks improves skin hydration, but not skin barrier function or the presence of redness or rash, when compared with not using topical oil. Furthermore, use of sunflower oil may impede the normal development of skin barrier function that occurs during the first four weeks of life (96144).
• Fetal and premature infant mortality. It is unclear if topical sunflower oil is beneficial for preventing early mortality in premature infants. Details: A large clinical trial in newborn infants in India shows that exclusive topical application of 10 mL of high-linoleic acid sunflower oil, an average of 2.7 times daily for about one month, reduces infant mortality by 58% when compared to a control group exclusively given traditional vigorous massage with mustard oil an average of 2.4 times daily. A subgroup analysis of premature infants also shows a 52% reduction in mortality with the use of high-linoleic acid sunflower oil when compared with control (108143). However, it is unclear if any beneficial effects are due to the sunflower oil, the massage, their combination, or the lack of mustard oil.
• Prematurity. Small to moderate-sized clinical studies suggest that topical sunflower oil might increase body weight, reduce length of hospital stay, and improve skin hydration and skin integrity in preterm neonates. Details: Preliminary clinical research in preterm infants with low birth weight shows that massaging for 5-10 minutes using sunflower oil 10 mL/kg three times daily for 2 weeks increases weight gain by approximately 35% over 2 months when compared with massage using no oil. Sunflower oil massage does not appear to increase length or head circumference (96145). A small clinical study in premature infants in the intensive care unit (ICU) shows that a similar massage with sunflower oil three times daily for 5 days shortens ICU stay by about 5 days when compared with no massage. Furthermore, over the ICU stay, infants in the sunflower oil massage group gained an average of 15 grams, whereas infants in the control group experienced weight loss (98479). The effect of sunflower oil on skin hydration and integrity in preterm infants has also been assessed. A clinical trial of 90 preterm infants in a Turkish neonatal ICU shows that whole body skin treatment (not massage) with either sunflower oil or almond oil 4 mL/kg four times daily for 5 days improves measures of skin hydration and skin integrity when compared with control infants that did not receive oil treatment. The sunflower and almond oil treatments are equally effective (105524). Another clinical study in 90 infants (42% preterm) in a Turkish neonatal ICU shows that whole body skin treatment (not massage) with sunflower oil or liquid Vaseline 3-4 mL for preterm and 5-6 mL for full-term infants daily for 16 days improves measures of skin integrity when compared with control infants that did not receive any oil treatment. Skin integrity scores were better in the sunflower oil group than liquid Vaseline at some time points (111726).
• Psoriasis. Although there is interest in using topical sunflower oil for psoriasis, there is insufficient reliable information about the clinical effects of sunflower oil for this condition.
• Rheumatoid arthritis (RA). Although there is interest in using oral sunflower oil for RA, there is insufficient reliable information about the clinical effects of sunflower oil for this condition.
• Tinea pedis. It is unclear if topical sunflower oil is beneficial for tinea pedis. Details: Preliminary clinical research shows that topical application of a specific brand of ozonized sunflower oil (Oleozon) twice daily for 6 weeks is as effective as ketoconazole for curing athlete's foot (76687). More evidence is needed to rate sunflower oil for these uses.

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POSSIBLY EFFECTIVE

• Athletic performance. Most available research suggests that oral tart cherry modestly improves muscular strength and endurance when compared with control. However, most studies are limited by a high risk of selection bias. Details: A meta-analysis of 14 small studies involving a total of 303 trained athletes and untrained healthy adults shows that tart cherry might modestly improve recovery of muscular strength and power when compared with control. Also, some subgroup analyses show that tart cherry may improve recovery of jump height and sprint time when compared with control (105629). In another meta-analysis of 10 studies involving 147 marathon runners, cyclists, or triathletes at various levels of training, taking tart cherry juice concentrate or powder 1.5 hours before exercise, or for up to 7 days prior to exercise, seems to improve exercise endurance, as measured by the time to complete an exercise trial, when compared with control (102340). However, both analyses have a high risk of selection bias and some analyses have high heterogeneity. Specific products assessed in the meta-analyses include tart cherry juice (CherryActive, Active Edge Nutrition) 60 mL, 90 minutes prior exercise (98699); a specific tart cherry concentrate (CherryActive, Active Edge Nutrition) 30 mL twice daily for 8 days (93149); and a specific freeze-dried tart cherry supplement (CherryPURE, Shoreline Fruit LLC) 480 mg daily 7 days before, on the day of, and 2 days after exercise (93158).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aromatase inhibitor-induced arthralgia. It is unclear if oral tart cherry is beneficial in patients with aromatase inhibitor-induced arthralgia (AIIA). Details: Preliminary clinical research in a small group of females with non-metastatic, hormone-receptor positive breast cancer and AIIA after taking aromatase inhibitors for at least 4 weeks shows that taking tart cherry juice concentrate 30 mL daily for 6 weeks reduces pain scores on a visual analog scale by about 35%, compared with 1% in those taking placebo (109657).
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral tart cherry juice is beneficial in children with ADHD. Details: A small clinical study in children and adolescents aged 6 to 18 years with ADHD shows that consuming tart cherry juice concentrate 75 mL twice daily for 2 weeks with standard treatment does not improve ADHD symptoms including cognitive impairment, hyperactivity, impulsivity, or oppositional behavior when compared with placebo (112815).
• Cognitive function. It is unclear if oral tart cherry improves cognitive function. Details: Preliminary clinical research in healthy, middle-aged adults shows that taking tart cherry juice concentrate 30 mL orally twice daily for 3 months reduces mental fatigue and improves performance on tests evaluating sustained attention, psychomotor speed, and alertness when compared with placebo. However, it does not affect sleep quality or cerebral blood flow (109655).
• Exercise-induced muscle soreness. Research on the use of oral tart cherry juice or supplements for the reduction of exercise-induced muscle soreness is conflicting. Details: A meta-analysis of 12 small studies in trained athletes and untrained healthy adults shows that tart cherry might modestly attenuate delayed muscle soreness after exercise involving maximal muscle contractions or maximal effort sprints when compared with control. However, tart cherry juice seems to be no better than placebo for improving delayed muscle soreness after prolonged aerobic exercise (105629). These findings are limited by a high risk of selection bias, high heterogeneity, and imprecision. Some products assessed in the meta-analysis include a specific Montmorency tart cherry concentrate (Holland & Barrett Ltd.) 30 mL twice daily for 5 days before, on the day of, and for 2 days after intermittent sprint exercises (102341); a specific freeze-dried tart cherry supplement (CherryPURE, Shoreline Fruit LLC) 480 mg daily for 7 days before, on the day of, and 2 days after running a half-marathon or doing back squats (93157,93158); a specific Montmorency tart cherry juice concentrate (CherryActive, Active Edge Nutrition) 30 mL diluted in water and taken twice daily for 8 days (93149,93151,101880,102344); and a specific juice (Sour cherry juice, Cherrypharm Inc.) containing 90% tart cherry juice and 10% apple juice as a sweetener, twice daily (93152,93154). Some individual clinical studies have yielded mixed findings. One clinical study in professional rugby players shows that taking a Montmorency tart cherry juice concentrate gel, 30 mL (equivalent to 100 cherries) twice daily for 2 days before, on the day of, and for 2 days after a match does not improve muscle soreness when compared with placebo (102339). Similarly, in male professional soccer players, taking tart cherry juice, 60 mL before and after a 90-minute match and then 12 and 36 hours later, does not improve subjective muscle soreness when compared with placebo (102342). Also, a small study in healthy males shows that taking a specific tart cherry supplement (Tart Cherry Extract Powder NordicCherry, Specnova, LLC.) 500 mg daily for 7 days prior to performing resistance exercise does not reduce muscle soreness when compared with placebo (105631). In contrast, a small clinical study in recreational long-distance runners shows that drinking a specific tart cherry juice (Cherrish, Cherrish Corp.) 10.5 ounces twice daily for 7 days prior to a long-distance race decreases post-race muscle pain by around 65% when compared with placebo (93156). Reasons for the discrepancies may include differences in tart cherry products, the small number of subjects, and heterogeneity in study populations and evaluated endpoints. In some studies, the subjects' normal diets were continued during the study, whereas in others, a reduced polyphenol diet was consumed for the duration of the study (102342,105629).
• Exercise-induced respiratory infections. It is unclear if oral tart cherry juice reduces the risk of exercise-induced respiratory infections. Details: A small clinical study in recreational athletes shows that drinking a specific juice blend (Sour cherry juice, Cherrypharm Inc.), containing 90% tart cherry juice and 10% apple juice as a sweetener, 8 ounces twice daily for 5 days before, on the day of, and 2 days after running a marathon, decreases the risk for upper respiratory tract symptoms such as cough, sore throat, congestion, and sneezing when compared with placebo (93168).
• Fibromyalgia. It is unclear if oral tart cherry improves symptoms in patients with fibromyalgia. Details: A very small clinical study in females with fibromyalgia participating in an eccentric exercise program shows that taking a specific tart cherry concentrate (Cherrish, Cherrish Corp.) 10.5 ounces twice daily for 14 days does not improve pain or muscle strength when compared with placebo (93192).
• Gout. It is unclear if oral tart cherry juice reduces symptoms of gout; research is conflicting. Details: Preliminary clinical research shows that tart cherry juice lowers serum urate and increases urinary urate excretion in healthy people, as well as people with hyperuricemia that has not progressed to gout (93166,102338). However, in patients with gout, taking Montmorency tart cherry juice concentrate (Cherryvite) in doses of 7.5-30 mL twice daily for 28 days does not affect urate excretion or the frequency of gout flares (102343). A small, unblinded clinical study in adults with chronic gout shows that taking a combination product (GoutFighter, MaxBiocare Pty Ltd.) containing tart cherry fruit extract 100 mg, celery seed extract 300 mg, devil's claw tuber extract 150 mg, folic acid 90 mcg, potassium citrate 50 mg, and ascorbic acid 50 mg orally, as 2 tablets twice daily for 45 days, modestly reduces mean serum uric acid levels and reduces perceived pain and frequency of joint swelling when compared to baseline (106488). The validity of these findings is limited by the lack of a comparator group. Additionally, it is unclear if any effects are due to tart cherry, other ingredients, or the combination.
• Hypertension. It is unclear if oral tart cherry juice reduces blood pressure; research is conflicting. Details: A very small clinical study in males with mild hypertension shows that taking 60 mL of a specific tart cherry concentrate (CherryActive, Active Edge Nutrition) modestly decreases systolic, but not diastolic, blood pressure 1-3 hours after consumption when compared with placebo (93155). This finding is limited by the small study size and the use of a single dose. Another small study in healthy adults without hypertension shows that drinking 30 mL of Montmorency tart cherry concentrate (Cherry Marketing Institute) diluted in 240 mL of water daily for 3 months does not reduce blood pressure when compared with baseline or placebo (105633).
• Insomnia. Some small clinical studies suggest that oral tart cherry juice may modestly improve sleep and reduce insomnia. This effect might be due to the melatonin content in tart cherry juice. However, the evidence is conflicting. Details: A small clinical study in healthy adults less than 40 years of age shows that consuming a specific tart cherry juice concentrate (CherryActive, Active Edge Nutrition) 30 mL standardized to contain 1.42 mcg/mL of melatonin twice daily for 7 days modestly increases total sleep time and efficiency when compared with placebo (17199). Another small clinical study in adults aged 65 years and older with chronic insomnia shows that drinking a specific juice blend (Sour cherry juice, Cherrypharm Inc.), containing 90% tart cherry juice and 10% apple juice as a sweetener, 8 ounces twice daily for 14 days, modestly improves insomnia severity, but not sleep latency, when compared with placebo (17403). However, another very small clinical study in healthy adults shows that taking Montmorency tart cherry juice 240 mL twice daily or powdered Montmorency tart cherry capsules 1000 mg daily for 30 days does not improve sleep quality, sleep time, or serum melatonin concentration when compared with placebo (112813). The effects of tart cherry on sleep measures have also been evaluated in combination with other ingredients. A very small crossover study in healthy adults without a sleep disorder shows that taking a combination product containing tart cherry powder 220 mg, tryptophan, glycine, magnesium, and L-theanine 2 hours before bedtime for 3 nights decreases the time to fall asleep by about 24 minutes, increases total sleep duration by about 22 minutes, improves sleep efficiency, and reduces morning sleepiness, but does not improve the total time in bed or wakefulness after falling asleep when compared with placebo (111184). It is unclear if these effects are due to tart cherry, other ingredients, or the combination.
• Metabolic syndrome. Oral tart cherry juice does not seem to improve cardiovascular or metabolic biomarkers in patients at risk for or with metabolic syndrome. Details: Two meta-analyses of small, moderate-quality clinical studies in healthy adults, patients with metabolic syndrome, or those with risk factors for metabolic syndrome, that include many of the same studies, show that drinking tart cherry juice 30-480 mL daily for 1-12 weeks does not improve fasting blood glucose, insulin levels, lipid profiles, blood pressure, body weight, body mass index, fat mass, percentage body fat, or waist circumference when compared with placebo (112812,112814).
• Osteoarthritis. It is unclear if oral tart cherry juice is beneficial in patients with osteoarthritis. Details: A small clinical study in patients with osteoarthritis shows that drinking a specific juice blend (Sour cherry juice, Cherrypharm Inc.) containing 90% tart cherry juice and 10% apple juice as a sweetener, 8 ounces twice daily for 6 weeks, does not improve pain, stiffness, function, walking speed, or acetaminophen use when compared with placebo (93160). The validity of this finding is limited because the trial was not adequately powered to detect small differences between groups. More evidence is needed to rate tart cherry for these uses.

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POSSIBLY SAFE ...when used orally and appropriately, short-term. Quercetin has been used with apparent safety in doses up to 1 gram daily for up to 12 weeks (481,1998,1999,16418,16429,16430,16431,96774,96775,96782)(99237,102539,102540,102541,104229,104679,106498,106499,107450,109620)(109621). ...when used intravenously and appropriately. Quercetin has been used with apparent safety in doses less than 945 mg/m2. Higher doses have been reported to cause nephrotoxicity (9564,16418). There is insufficient reliable information available about the safety of quercetin when used topically.

POSSIBLY UNSAFE ...when used intravenously in large amounts. Doses greater than 945 mg/m2 have been reported to cause nephrotoxicity (9564,16418).

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

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LIKELY SAFE ...when used orally and appropriately in amounts commonly found in foods. When used as a substitute for other dietary oils, the recommended intake of high-oleic acid sunflower oil is 20 grams (1.5 tablespoons) daily (9780,98563). ...when used topically and appropriately, short-term. Sunflower oil has been applied to the skin twice daily for up to 6 weeks (76687). There is insufficient reliable information available about the safety of sunflower oil when used as an oral rinse.

CHILDREN: LIKELY SAFE
when used orally and appropriately in amounts commonly found in foods.

CHILDREN: POSSIBLY SAFE
when applied topically and appropriately, short-term. Sunflower oil has been applied to the skin of infants daily for up to 2 months (96144,96145,105524,108143). There is insufficient reliable information available about the safety of sunflower oil when used orally in larger amounts as medicine.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately in amounts commonly found in foods. There is insufficient reliable information available about the safety of sunflower oil when used in amounts greater than those found in food.

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LIKELY SAFE ...when the fruit is used in amounts commonly found in foods. ...when tart cherry fruit, fruit juice, or fruit juice concentrate is used orally in supplemental amounts for up to 3 months (17403,93149,93151,93152,93153,93154,93156,93157,93158,93160)(93161,93168,93179,105633).

POSSIBLY SAFE ...when tart cherry fruit extract or powder is used orally, short term. Cherry fruit extract or freeze-dried cherry powder up to 500 mg daily for up 7 days has been used with apparent safety (93157,93158,105631). There is insufficient reliable information available about the safety of tart cherry stem when used orally.

PREGNANCY AND LACTATION: LIKELY SAFE
when the fruit is consumed in typical food amounts. There is insufficient reliable information available about the safety of tart cherry fruit or stem when used in medicinal amounts; avoid using.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of quercetin and antidiabetes drugs might increase the risk of hypoglycemia.  Details Clinical research suggests that a combination of quercetin, myricetin, and chlorogenic acid reduce levels of fasting glucose in patients with type 2 diabetes, including those already taking antidiabetes agents (96779). The effect of quercetin alone is unknown.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking quercetin with antihypertensive drugs might increase the risk of hypotension.  Details Quercetin can modestly decrease blood pressure in people with mild hypertension (16424,96780). Theoretically, it might have additive blood pressure lowering effects when used with antihypertensive drugs.

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of cyclosporine.  Details A small study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine, possibly due to inhibition of p-glycoprotein or cytochrome P450 3A4 (CYP3A4), which metabolizes cyclosporin (16434).

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of CYP2C8 substrates.  Details In vitro research shows that quercetin inhibits CYP2C8 (16432,16435). Inhibition of paclitaxel (Taxol) metabolism via CYP2C8 has been reported in vitro (16436). However, a small study in humans found no effect of quercetin on rosiglitazone (Avandia), which is also a CYP2C8 substrate (16432).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of CYP2C9 substrates.  Details A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac, a CYP2C9 substrate, increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5% (97931). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar), a substrate of CYP2C9 (100968). Furthermore, laboratory research shows that quercetin inhibits CYP2C9 (15549,16433).

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.  Details In vitro research show that quercetin inhibits CYP2D6 (15549,16433). This effect has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might alter the effects and adverse effects of CYP3A4 substrates.  Details A small clinical study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine (Neoral, Sandimmune), a substrate of CYP3A4 (16434). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) and quetiapine (Seroquel), substrates of CYP3A4 (100968,104228). Other laboratory research also shows that quercetin inhibits CYP3A4 (15549,16433,16435). However, one clinical study shows that quercetin can increase the metabolism of midazolam, a substrate of CYP3A4, and decrease serum concentrations of midazolam by about 24% in some healthy individuals, suggesting possible induction of CYP3A4 (91573).

DICLOFENAC (Voltaren, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of diclofenac.  Details A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5%. This is thought to be due to inhibition of CYP2C9 by quercetin (97931).

LOSARTAN (Cozaar) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of losartan and decrease the effects of its active metabolite.  Details Animal research shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) while decreasing plasma levels of losartan's active metabolite. This metabolite, which is around 10-fold more potent than losartan, is the result of cytochrome P450 (CYP) 2C9- and CYP3A4-mediated transformation of losartan. Additionally, in vitro research shows that quercetin may inhibit P-glycoprotein-mediated efflux of losartan from the intestines, resulting in increased absorption of losartan (100968). These results suggest that concomitant use of quercetin and losartan might increase systemic exposure to losartan while also decreasing plasma concentrations of losartan's active and more potent metabolite.

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might decrease the levels and effects of midazolam.  Details A small clinical study in healthy volunteers shows that quercetin can increase the metabolism of midazolam, with a decrease in AUC of about 24% (91573).

MITOXANTRONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of mitoxantrone.  Details In vitro research shows that quercetin increases the intracellular accumulation and cytotoxicity of mitoxantrone, possibly through inhibition of breast cancer resistance protein (BCRP), of which mitoxantrone is a substrate (107897). So far, this interaction has not been reported in humans.

ORGANIC ANION TRANSPORTER 1 (OAT1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of OAT1 substrates.  Details In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT1, with half-maximal inhibitory concentration (IC50) values less than 10 mcM (104454). So far, this interaction has not been reported in humans.

ORGANIC ANION TRANSPORTER 3 (OAT3) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.  Details In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT3, with half-maximal inhibitory concentration (IC50) values as low as 0.75 mcM (104453,104454). So far, this interaction has not been reported in humans.

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of OATP substrates.  Details In vitro evidence shows that quercetin can inhibit organic anion-transporting peptide (OATP) 1B1-mediated uptake of estrone-3-sulfate and pravastatin (91581). Furthermore, clinical research in healthy males shows that intake of quercetin along with pravastatin increases the AUC of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581).

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might alter the effects and adverse effects of P-glycoprotein substrates.  Details There is preliminary evidence that quercetin inhibits the gastrointestinal P-glycoprotein efflux pump, which might increase the bioavailability and serum levels of drugs transported by the pump (16433,16434,16435,100968,104228). A small study in healthy volunteers reported that pretreatment with quercetin increased bioavailability and plasma levels after a single dose of cyclosporine (Neoral, Sandimmune) (16434). Also, two small studies have shown that quercetin might decrease the absorption of talinolol, a substrate transported by the gastrointestinal P-glycoprotein efflux pump (91579,91580). However, in another small study, several days of quercetin treatment did not significantly affect the pharmacokinetics of saquinavir (Invirase) (16433). The reason for these discrepancies is not entirely clear (91580). Until more is known, use quercetin cautiously in combination with P-glycoprotein substrates.

PRAVASTATIN (Pravachol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of pravastatin.  Details In vitro evidence shows that quercetin can inhibit OATP 1B1-mediated uptake of pravastatin (91581). Also, preliminary clinical research in healthy males shows that intake of quercetin along with pravastatin increases the maximum concentration of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581).

PRAZOSIN (Minipress) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of prazosin.  Details In vitro research shows that quercetin inhibits the transcellular efflux of prazosin, possibly through inhibition of breast cancer resistance protein (BCRP), of which prazosin is a substrate. BCRP is an ATP-binding cassette efflux transporter in the intestines, kidneys, and liver (107897). So far, this interaction has not been reported in humans.

QUETIAPINE (Seroquel) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of quetiapine.  Details Animal research shows that pretreatment with quercetin can increase plasma levels of quetiapine and prolong its clearance, possibly due to inhibition of cytochrome P450 3A4 (CYP3A4) by quercetin. Additionally, the brain-to-plasma ratio of quetiapine concentrations increased, possibly due to inhibition of P-glycoprotein at the blood-brain barrier (104228). This interaction has not been reported in humans.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might inhibit the effects of quinolone antibiotics.  Details In vitro, quercetin binds to the DNA gyrase site on bacteria (481), which may interfere with the activity of quinolone antibiotics.

SULFASALAZINE (Azulfidine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of sulfasalazine.  Details Animal research shows that quercetin increases the maximum serum concentration (Cmax) and area under the curve (AUC) of sulfasalazine, possibly through inhibition of breast cancer resistance protein (BCRP), of which sulfasalazine is a substrate (107897). So far, this interaction has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin may increase the risk of bleeding if used with warfarin.  Details Animal and in vitro studies show that quercetin might increase serum levels of warfarin (17213,109619). Quercetin and warfarin have the same human serum albumin (HSA) binding site, and in vitro research shows that quercetin has stronger affinity for the HSA binding site and can theoretically displace warfarin, causing higher serum levels of warfarin (17213). Animal research shows that taking quercetin for 2 weeks before initiating warfarin increases the maximum serum level of warfarin by 30%, the half-life by 10%, and the overall exposure by 63% when compared with control. Concomitant administration of quercetin and warfarin, without quercetin pre-treatment, also increased these measures, but to a lesser degree. Researchers theorize that inhibition of CYP3A4 by quercetin may explain these effects (109619). So far, this interaction has not been reported in humans.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, sunflower oil might decrease the effectiveness of antidiabetes medications.  Details A diet using sunflower oil as a fat source can cause increased fasting blood glucose levels in patients with type 2 diabetes (8132). Dose adjustments to diabetes medications might be necessary.

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General ...Orally and intravenously, quercetin seems to be well tolerated in appropriate doses. Topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

Gastrointestinal ...Intravenous administration of quercetin is associated with nausea and vomiting (9564).

Neurologic/CNS ...Orally, quercetin may cause headache and tingling of the extremities (481,111500). Intravenously, quercetin may cause pain at the injection site. Injection pain can be minimized by premedicating patients with 10 mg of morphine and administering amounts greater than 945 mg/m² over 5 minutes (9564). In addition, intravenous administration of quercetin is associated with flushing and sweating (9564).

Pulmonary/Respiratory ...Intravenous administration of quercetin at doses as high as 2000 mg/m² is associated with dyspnea that may persist for up to 5 minutes (9564).

Renal ...Intravenously, nephrotoxicity has been reported with quercetin in amounts greater than 945 mg/m² (9563,9564,70304).

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General ...Orally and topically, sunflower oil is well tolerated.
Serious Adverse Effects (Rare):
Orally: Allergic reactions in sensitive individuals have been reported.

Immunologic ...Orally, sunflower oil can cause an allergic reaction in individuals sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many other herbs. However, the protein content of sunflower oil is very low. In one case report, an allergic response to sunflower oil did not occur despite presenting with severe allergy and anaphylaxis to sunflower seed (108140).

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General ...Tart cherry is generally well tolerated when consumed as whole fruit, juice concentrate, or seed extracts.
Most Common Adverse Effects:
Orally: Abdominal pain, asthenia, gastrointestinal upset, loose stools.

Endocrine ...One case of hyperglycemia after drinking a specific blend of tart cherry and apple juices ) has been reported (93160).

Gastrointestinal ...In a clinical study, 29% of children who consumed 75 mL of tart cherry juice concentrate twice daily for 2 weeks reported abdominal pain (112815). Two cases of loose stools after consumption of 90 whole tart cherries, and one case of gastrointestinal disturbance after drinking 10.5 ounces of tart cherry concentrate (Cherrish, Cherrish Corp.) twice daily for 14 days have been reported (93186,93192). One case of gastrointestinal symptoms after drinking a specific blend of tart cherry and apple juice (Sour cherry juice, Cherrypharm Inc.) has been reported (93160).

Immunologic ...One case of a skin reaction possibly due to cherry allergy after drinking a specific blend of tart cherry and apple juice ) has been reported (93160).

Musculoskeletal ...In a clinical study, 31% of children who consumed tart cherry juice concentrate 75 mLl twice daily for 2 weeks reported asthenia (112815).

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