Quercetin is one of the most active flavonoids, with many medicinal plants owing much of their activity to their high quercetin content. It has been shown in experimental studies to have numerous effects on the body including the inhibition of both the production and release of histamine. However, it is probably most well known for its antioxidant action, with more recent studies also demonstrating its potential for contributing to cardiovascular health. LAMBERTS quercetin is extracted from a plant source and our tablets provide a full 500mg of pure quercetin. Cheap quercetin products, particularly those imported from the USA, may contain much less quercetin than the label declaration, as the weight being given refers to the plant extract, not to the quercetin content. Quercetin is found in many fruits and vegetables, with apples and onions contributing most to the typical UK diet. Each 500mg tablet provides significantly more quercetin than 1 kilo of apples. About Lamberts LAMBERTS is the UK's leading supplier of food supplements to Practitioners, GP's, Nutritionists and Pharmacists who use nutrition in healthcare. Their healthcare philosophy consists of sound science - they only develop health products supported by a valid scientific rationale, and always at the right potency for maximum benefit. LAMBERTS quercetin is extracted from a plant source and our tablets provide a full 500mg of pure quercetin. Quercetin is found in many fruits and vegetables, with apples and onions contributing most to the typical UK diet.