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Quest Vitamins LTD,
8 Venture Way,
Aston Science Park,
B7 4AP.

Tel: 0121 359 0056
Fax: 0121 359 0313
Registered in England No. 2530437



Quercetin belongs to the class of Bioflavonoids, which consists of water-soluble plant colouring agents. It is a natural antioxidant found in red wine. Quercetin protects the cells of the body from free radical damage. It may help prevent heart disease and Strokes by preventing free radical damage to blood vessels. Quercetin is also recommended as a treatment for allergies and related conditions.


200 to 400 mg three times daily.

Quercetin is better absorbed if taken on an empty stomach.


Allergic conditions:
Quercetin is most popularly used as a treatment for allergic conditions, including Asthma, Hay Fever, Eczema, and Hives. Animal research has shown that quercetin blocks histamine release by immune cells (1). However, there is no evidence available to demonstrate the effectiveness of quercetin supplements in treating Allergy symptoms.

Heart health:
Preliminary evidence indicates that quercetin may help prevent heart disease and Strokes (2,3).


Nursing and pregnant women, young children, and patients with serious liver or kidney disease should take caution with quercetin, since maximum safe levels have not yet been established for these groups.


There are no known drug interactions or contra-indications for quercetin.


Quercetin is found in red wine, grapefruit, onions, apples, and black tea. It is also found in lesser amounts in leafy green vegetables and beans. However, to obtain therapeutic dosages, one needs to take supplements.


1. Ogasawara H and Middleton E Jr. Effect of selected flavonoids on histamine release (HR) and hydrogen peroxide generation by human leukocytes. J Allergy Clin Immunol 75: 184, 1985.
2. Constant J. Alcohol, ischemic heart disease, and the French paradox. Coron Artery Dis 8: 645-649, 1997.
3. Keli SO, et al. Dietary flavonoids, antioxidant vitamins, and incidence of Stroke: the Zupthen study. Arch Intern Med 147: 637-642, 1996.

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