A flavonol widely distributed in plants. It is an antioxidant, like many other phenolic heterocyclic compounds. Glycosylated forms include RUTIN and quercetrin. Isol. from many plants, esp. fruits, such as Helichrysum, Euphorbia and Karwinskia spp. Present in the Solanaceae, Rhamnaceae, Passifloraceae and many other families. For example detected in almost all studied Umbelliferae. Nutriceutical with antiinflammatory props. and a positive influence on the blood lipid profile. Found in a wide variety of foodstuffs esp. apples, bee pollen, blackcurrants, capers, cocoa, cranberries, dock leaves, elderberries, fennel, lovage, red onions, ancho peppers, dill weed and tarragon


Quercetin is a flavonoid widely distributed in many plants and fruits including red grapes, citrus fruit, tomato, broccoli and other leafy green vegetables, and a number of berries, including raspberries and cranberries. Quercetin itself (aglycone quercetin), as opposed to quercetin glycosides, is not a normal dietary component. Quercitin glycosides are converted to phenolic acids as they pass through the gastrointestinal tract. Quercetin has neither been confirmed scientifically as a specific therapeutic for any condition nor been approved by any regulatory agency. The U.S. Food and Drug Administration has not approved any health claims for quercetin. Nevertheless, the interest in dietary flavonoids has grown after the publication of several epidemiological studies showing an inverse correlation between dietary consumption of flavonols and flavones and reduced incidence and mortality from cardiovascular disease and cancer. In recent years, a large amount of experimental and some clinical data have accumulated regarding the effects of flavonoids on the endothelium under physiological and pathological conditions. The meta-analysis of seven prospective cohort studies concluded that the individuals in the top third of dietary flavonol intake are associated with a reduced risk of mortality from coronary heart disease as compared with those in the bottom third, after adjustment for known risk factors and other dietary components. A limited number of intervention studies with flavonoids and flavonoid containing foods and extracts has been performed in several pathological conditions. (A7896)

Quercetin is Found in These Foods

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Quercetin Health Effects

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Mechanism of Action

Quercetin Interacts with Diseases