Flavonoids

Flavonoids: What do they do?

are a class of water-soluble plant pigments. are broken down into categories, though the issue of how to divide them is not universally agreed upon. One system breaks flavonoids into isoflavones, anthocyanidins, flavans, flavonols, flavones, and flavanones.¹ Some of the best-known flavonoids, such as genistein in soy, and quercetin in onions, can be considered subcategories of categories. Although they are all structurally related, their functions are different. also include hesperidin, rutin, citrus flavonoids, and a variety of other supplements.

While they are not considered essential nutrients, some flavonoids support health by strengthening capillaries and other connective tissue, and some function as anti-inflammatory, antihistaminic, and antiviral agents. Quercetin has been reported to block the "sorbitol pathway" that is linked to many problems associated with diabetes. Rutin and several other flavonoids may also protect blood vessels.

As antioxidants, some flavonoids, such as quercetin, protect LDL ("bad") cholesterol from oxidative damage. Others, such as the anthocyanidins from bilberry, purple cabbage, and grapes, may help protect the lens of the eye from cataracts. Animal research suggests that naringenin, found in grapefruit, may have anticancer activity.² Soy isoflavones are also currently being studied to see if they help fight cancer.

In a small, preliminary trial, rutoside (500 mg twice daily), a derivative of the flavonoid, rutin, combined with vitamin C (500 mg twice daily) produced marked improvement in three women with progressive pigmented purpura (PPP), a mild skin condition.³ Although not a serious medical condition, cosmetic concerns lead persons with PPP to seek treatment with a variety of drugs. The vitamin C/rutoside combination represents a promising, non-toxic alternative to these drug treatments, but larger, controlled trials are needed to confirm these preliminary results.