After a review of several clinical studies, the AHA's Nutrition Committee has concluded that eating 25 to 50 grams of soy protein daily can help reduce blood levels of "bad" cholesterol (low-density lipoproteins or LDL) by 4 percent to 8 percent. The effect is greater in people with high cholesterol, the committee says, a known risk factor for coronary heart disease.

"It is prudent to recommend including soy protein foods in a diet low in saturated fat and cholesterol to promote heart health," writes John Erdman, Jr., Ph.D., in an advisory published in Circulation, A Journal of the American Heart Association.

Soy protein is obtained from raw whole soybeans and can be found in tofu, soymilk, soy yogurt, and miso, a paste made from soybeans.

Researchers have long noted that people in Asia, where soybean products are dietary staples, have lower rates of cardiovascular disease than Americans. Up to 55 grams of soy protein per day are consumed by the Japanese, according to the advisory, whereas Americans eat less than 5 grams per day.

Among the important soy components are isoflavones, which are plant estrogens. Soy products without isoflavones seem less effective in lowering cholesterol, but the AHA says research findings do not support taking isoflavones alone as dietary supplements.

The advisory acknowledges that Americans are not familiar with the various sources of soy protein. "In the past 10 years, the variety of soy foods available in U.S. stores has increased, yet food manufacturers still need to provide more acceptable soy-based foods for the consumer," Dr. Erdman writes.

Donald D. Hensrud, M.D., a nutrition specialist at Mayo Clinic, Rochester, Minn., agrees that people should broaden their tastes.

"The challenge for the public is to try to include foods such as tofu, tempeh, miso, textured vegetable protein, soy milk and soy cheese in their diet regularly," Dr. Hensrud says. "If people try these products using creative ways to prepare them, they may discover palatable and enjoyable new foods and improve their health in the process. "