Citrus fruits are well known for providing ample amounts of vitamin C. But they also supply bioflavonoids, substances that are not required for life but that may improve health. The major bioflavonoids found in citrus fruits are diosmin, hesperidin, rutin, naringin, tangeretin, diosmetin, narirutin, neohesperidin, nobiletin, and quercetin.

This article addresses the first five bioflavonoids listed above. Please see the article Quercetin for information on this supplement. A modified form of rutin, oxerutin, is also discussed in its own article.

Citrus bioflavonoids and related substances are widely used in Europe to treat diseases of the blood vessels and lymph system, including hemorrhoids, chronic venous insufficiency, leg ulcers, easy bruising, nosebleeds, and lymphedema following breast cancer surgery. These compounds are thought to work by strengthening the walls of blood vessels. Bioflavonoids are also often said to act as antioxidants; however, while they do have antioxidant activity in the test tube, growing evidence suggests that they do not act as antioxidants in people.45

Citrus fruits contain citrus bioflavonoids in varying proportions. Even different brands of citrus juice may vary widely in their bioflavonoid concentrations and composition.1 For use as a supplement, bioflavonoids are extracted either from citrus fruits or other plant sources, such as buckwheat.