Quercetin is a flavonoid that forms the "backbone" for many other flavonoids, including the citrus flavonoids rutin, hesperidin, naringin and tangeritin. Quercetin is found to be the most active of the flavonoids in studies, and many medicinal plants owe much of their activity to their high quercetin content. Quercetin has demonstrated significant anti-inflammatory activity because of direct inhibition of several initial processes of inflammation. For example, it inhibits both the manufacture and release of histamine and other allergic/inflammatory mediators. In addition, it exerts potent antioxidant activity and vitamin C-sparing action.
Together with rhamnose, it forms a glycoside quercitrin.
Quercetin may be a major reason why the old adage about eating "an apple a day" has been associated with good health. And why a daily cup of tea is more than a comforting ritual. Quercetin, which is primarily found in apples, onions, and black tea, is a type of flavonoid (plant pigment) that serves as a building block for other members of the flavonoid family.
Quercetin and other dietary flavonoids have been receiving good health-related press in recent years, and for good reason.
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