* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
As a dietary supplement, take one caplet daily. For maximum support, take as directed every day.
|Serving Size 1 Caplet|
|Servings Per Container 60|
|Amount Per Serving||% DV|
|Quercetin (as Quercetin Dihydrate)||500.00 mg||**|
|** Daily Value (DV) not established|
Other Ingredients: Cellulose, Food Glaze
No Sugar, No Artificial Colors, No Artificials Flavors, No Preservatives, Sodium Free, No Wheat, No Gluten, No Soy, No Diary, Yeast Free
Distributed by: General Nutrition Corporation Pittsburgh, PA 15222
Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
Quercetin, a flavonoid with anti-inflammatory and antioxidant effects, has recently been reported to improve symptoms of NBP and PD. An uncontrolled study reported that 500 mg of quercetin twice daily for at least two weeks significantly improved symptoms in 59% of men with chronic prostatitis.1 These results were confirmed in a double-blind study, in which similar treatment with quercetin for one month improved symptoms in 67% of men with NBP or PD.2 Another uncontrolled study combined 1,000 mg per day of quercetin with the enzymes bromelain and papain, resulting in significant improvement of symptoms.3 Bromelain and papain promote absorption of quercetin and have anti-inflammatory effects as well.4
1. Shoskes DA. Use of the bioflavonoid quercetin in patients with longstanding chronic prostatitis. JANA 1999;2:36-9.
2. Shoskes DA, Zeitlin SI, Shahed A, Rajfer J. Quercetin in men with category III chronic prostatitis: a preliminary prospective, double-blind, placebo-controlled trial. Urology 1999; 54:960-3.
3. Shoskes DA, Zeitlin SI, Shahed A, Rajfer J. Quercetin in men with category III chronic prostatitis: a preliminary prospective, double-blind, placebo-controlled trial. Urology 1999; 54:960-3.
4. Izaka K, Yamada M, Kawano T, Suyama T. Gastrointestinal absorption and anti-inflammatory effect of bromelain. Jpn J Pharmacol 1972;22:519-34.
Many of the effects of allergic reactions are caused by the release of histamine, which is the reason antihistamine medication is often used by allergy sufferers. Some natural substances, such as vitamin C1, 2 and flavonoids,3 including quercetin,4, 5 have demonstrated antihistamine effects in test tube, animal, and other preliminary studies. However, no research has investigated whether these substances can specifically reduce allergic reactions in humans.
1. Johnston CS, Retrum KR, Srilakshmi JC. Antihistamine effects and complications of supplemental vitamin C. J Am Diet Assoc 1992;92:988-9.
2. Johnston S, Martin LJ, Cai X. Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis. J Am Coll Nutr 1992;11:172-6.
3. Gabor M. Anti-inflammatory and anti-allergic properties of flavonoids. Prog Clin Biol Res 1986;213:471-80 [review].
4. Middleton E, Drzewieki G. Naturally occurring flavonoids and human basophil histamine release. Int Arch Allergy Appl Immunol 1985;77:155-7.
5. Amella M, Bronner C, Briancon F, et al. Inhibition of mast cell histamine release by flavonoids and bioflavonoids. Planta Medica 1985;51:16-20.
Quercetin, a flavonoid found in most plants, has an inhibiting action on lipoxygenase, an enzyme that contributes to problems with asthma.1 No clinical trials in humans have confirmed whether quercetin decreases asthma symptoms. Some doctors are currently experimenting with 400 to 1,000 mg of quercetin three times per day.
Quercetin is an increasingly popular treatment for hay fever even though only limited preliminary clinical research has suggested that it is beneficial to hay fever sufferers.1
Quercetin, a flavonoid, protects LDL cholesterol from damage.1 While several preliminary studies have found that eating foods high in quercetin lowers the risk of heart disease,2, 3, 4 the research on this subject is not always consistent,5 and some research finds no protective link.6 Quercetin is found in apples, onions, black tea, and as a supplement. In some studies, dietary amounts linked to protection from heart disease are as low as 35 mg per day.
1. Ronzio RA. Antioxidants, nutraceuticals and functional foods. Townsend Letter for Doctors and Patients 1996;Oct:34-5 [review].
2. Hertog MGL, Feskens EJM, Hollman PCH, et al. Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study. Lancet 1993;342:1007-11.
3. Hertog MGL, Kromhout D, Aravanis C, et al. Flavonoid intake and long-term risk of coronary heart disease and cancer in the Seven Countries Study. Arch Intern Med 1995;155:381-6.
4. Knekt P, Jarvinen R, Reunanen A, Maatela J. Flavonoid intake and coronary mortality in Finland: a cohort study. BMJ 1996;312:478-81.
5. Rimm EB, Katan MB, Ascherio A, et al. Relation between intake of flavonoids and risk for coronary heart disease in male health professionals. Ann Intern Med 1996; 125:384-9.
6. Hertog MGL, Sweetnam PM, Fehily AM, et al. Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study. Am J Clin Nutr 1997;65:1489-94.
Flavonoids are a group of compounds found in some plant foods and medicinal herbs. An antiviral action of some flavonoids has been observed in a number of test tube experiments.1, 2, 3, 4, 5Quercetin, one of the flavonoids, has shown particularly strong antiviral properties in the test tube;6, 7, 8 however, one study did not find quercetin to be of benefit to mice with a viral infection.9 It is not known whether flavonoids can be absorbed in amounts sufficient to exert an antiviral effect in humans, and therefore their possible role in the treatment of childhood exanthems remains unknown.
1. Vrijsen R, Everaert L, Boeye A. Antiviral activity of flavones and potentiation by ascorbate. J Gen Virol 1988;69:1749-51.
2. Debiaggi M, Tateo F, Pagani L, et al. Effects of propolis flavonoids on virus infectivity and replication. Microbiologica 1990;13:207-13.
3. Fesen MR, Kohn KW, Leteurtre F, Pommier Y. Inhibitors of human immunodeficiency virus integrase. Proc Natl Acad Sci 1993;90:2399-403.
4. Amoros M, Simoes CM, Girre L, et al. Synergistic effect of flavones and flavonols against herpes simplex virus type 1 in cell culture. Comparison with the antiviral activity of propolis. J Nat Prod 1992;55:1732-40.
5. Spedding G, Ratty A, Middleton E Jr. Inhibition of reverse transcriptases by flavonoids. Antiviral Res 1989;12:99-110.
6. Kaul TN, Middleton E Jr, Ogra PL. Antiviral effect of flavonoids on human viruses. J Med Virol 1985;15:71-9.
7. Mucsi I, Pragai BM. Inhibition of virus multiplication and alteration of cyclic AMP level in cell cultures by flavonoids. Experientia 1985;41:930-1.
8. Ohnishi E, Bannai H. Quercetin potentiates TNF-induced antiviral activity. Antiviral Res 1993;22:327-31.
9. Esanu V, Prahoveanu E, Crisan I, Cioca A. The effect of an aqueous propolis extract, of rutin and of a rutin-quercetin mixture on experimental influenza virus infection in mice. Virologie 1981;32:213-5.
In test tube studies, quercetin, a flavonoid, has inhibited an enzyme involved in the development of gout.1, 2 However, it is not known whether taking quercetin by mouth can produce high enough quercetin concentrations in the body to achieve these effects. Although human research is lacking, some doctors recommend 150-250 mg of quercetin three times per day (taken between meals).
The flavonoidquercetin may also help by blocking sorbitol accumulation in the eye.1 This may be especially helpful for people with diabetes, though no clinical trials have yet explored whether quercetin actually prevents diabetic cataracts.
Quercetin belongs to a class of water-soluble plant pigments called flavonoids.
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2016.