What it is. Bioflavonoids are a group of plant pigments that give fruits and flowers some of their color. Some bioflavonoids act as powerful antioxidants, "many of which are more potent than better known antioxidants such as vitamins C and E," explains Shari Lieberman, Ph.D., a nutrition scientist and exercise physiologist in New York City.

How it delays aging. Bioflavonolds may help lower the risk of heart disease. In 1996, a Finnish study found that women who ate the most flavonoids had a 46 percent lower risk for heart disease than those who ate the least.

Bioflavonoids keep the tiny disks in our blood (called platelets), which help blood clot, from clumping together and forming clots that can block the arteries. They also keep harmful lowdensity lipoprotein (LDL) cholesterol from oxidizing and sticking to artery walls.

Some bioflavonoids can stop cancer before it starts. To give just a few examples, quercetin, found in apples, yellow and red onions, and tea, has been shown in test tube studies to discourage the growth of tumors and prevent malignant cells from spreading. And rutin, found in buckwheat, helps reduce cancer risk through its action as an antioxidant.

What you'll find. You can get bioflavonolds by eating fruits and vegetables or by taking them in supplement form. Supplements may contain either a single bioflavonoid or several in combination, says Michael Janson, M.D., president of the American College for Advancement in Medicine and author of three books including Dr. janson's Vitamin Revolution. These usually contain extracts of quercetin, hesperidin, rutin, and citrus bioflavonoids and come in 500 or 1,000 milligram doses.

How much to take: Dr. Janson recommends taking 1,000 milligrams once or twice a day. As powerful antioxidants themselves, bioflavonoids increase the absorption of vitamin C.

Be aware: They are generally regarded as safe.