What are flavonoids?
Many of our vegetable sources of nutrition are rich in pigments called flavonoids, or bioflavonoids, that are not only colorful and attractive but are also important sources of health benefits. They help to prevent serious diseases and the degenerative problems associated with oxidative free-radical damage. Hundreds, if not thousands, of these flavonoids occur in plants that are common in ethnic diets around the world. Unfortunately, Americans eat very few fruits and vegetables, so they miss the many benefits of these substances. (The most common “vegetable” that kids eat today is—you guessed it, french fries! which is not really a vegetable at all, but a carrier for highly processed and overcooked hydrogenated fats, while potatoes themselves have virtually no fat.) Even more exciting, the medical literature now supports the view that supplements of flavonoids can be healing substances that can substitute for drugs for many patients or reduce the doses of medication that they need. Many of the flavonoids have recently been included in the term “phytochemicals,” which just means “plant chemicals.” Flavonoids protect against cancer and heart disease and they enhance the activity of vitamin C.
One good example is quercetin. It is a yellow-green flavonoid found in red and yellow onions (but not in white onions), although the amounts found in foods are relatively small compared to therapeutic doses. In allergic reactions, histamine is released from mast cells in the tissues. The membranes of these cells are stabilized by quercetin, so their histamine is not released as readily, thus reducing the allergic response. (Interestingly, a synthetic flavonoid called “cromolyn sodium” is used for allergies under the brand name Intal®). Effective doses of quercetin range from 800-1200 mg daily, far higher than the amount found in foods. This is important because sometimes people may try supplements in too low a dose, and then give up without getting results.