IMPORTANCE: They are vital in their ability to increase the strength of the capillaries (blood vessels) and to regulate their permeability. They assist Vitamin C in keeping collagen, the intercellular “cement” in healthy condition; are essential for the proper absorption and use of vitamin C; prevents Vitamin C from being destroyed in the body by oxidation; beneficial in hypertension; helps hemorrhages and ruptures in the capillaries and connective tissues and builds a protective barrier against infections. Quercetin is a very highly concentrated form of Bioflavonoids derived from citrus fruits.
    DEFICIENCY SYMPTOMS: May result in varicose veins, tendency to bruise and bleed easily, appearance of purplish spots on the skin.

—courtesy of Austin Nutritional research

    Phytonutrients of this phenol subclass enhance the effects of ascorbate-vitamin C. Flavonoids were once lumped together as vitamin P, but there are well over 1,500 of them. Here is a partial listing:

• Flavones (containing the flavonoid apigenin found in chamomile);
• Flavonols (quercetin—grapefruit; rutin—buckwheat; ginkgoflavonglycosides—ginkgo);
• Flavanones (hesperidin—citrus fruits; silybin—milk thistle);

    The biologic activities of flavonoids include action against allergies, inflammation, free radicals, hepatotoxins, platelet aggregation, microbes, ulcers, viruses and tumors.⁸ Flavonoids also inhibit specific enzymes. For example, flavonoids block the angiotensin-converting enzyme (ACE) that raises blood pressure: By blocking the “suicide” enzyme cyclooxygenase that breaks down prostaglandins, they prevent platelet stickiness and hence platelet aggregation. Flavonoids also protect the vascular system and strengthen the tiny capillaries that carry oxygen and essential nutrients to all cells.⁹

    Additionally, flavonoids block the enzymes that produce estrogen, thus reducing the risk of estrogen-induced cancers. One way they do this is by blocking estrogen synthsase, an enzyme that works overtime in binding estrogen to receptors in several organs.¹⁰

    Although their way of doing so is not yet fully understood, flavonoids also appear to retard development of cataracts in individuals with inborn errors in sugar metabolism such as diabetes.¹¹ Cataracts can be a complication of diabetes because diabetics, unable to metabolize sugar normally, build up damaging levels of “alcohol sugars.” These in turn cause clouding of the lens of the eye (cataract). It is suspected flavonoids prevent cataracts by blocking aldose-reductase (a digestive enzyme), which can convert the sugar galactose into the potentially harmful form of galacticol.

8. Kinsella, J.E., et al. Food Technology, 47: 85-90, April 1993.

9. Ibid.

10. Northrup, C. Women's Bodies, Women’s Wisdom: 305. New York; Bantam Books, 1994.

11. Murray, R.K., et al. Harper’s Biochemistry, 23 ed.: 196. New York; Appleton & Lange, 1994.

—courtesy of Austin Nutritional research