Compounds widely distributed in nature as pigments in flowers, fruit, vegetables, and tree barks. Chemically they are glycosides of flavones; the sugar moiety may be either rhamnose or rhamnoglucose, and depending on the different reactive groups in the flavone may be flavonols, flavanones, flavonals, or isoflavones.

Some of the flavonoids have pharmacological actions, but they are not known to be dietary essentials, although claims have been made (they were at one time classified as vitamin P), and are sometimes called bioflavonoids. They may make a contribution to the total antioxidant intake, and some are phytoestrogens.

A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.