WINSTON-SALEM, NC -- The cholesterol-lowering effect of soy is the result of natural compounds in the soy known as isoflavones, Wake Forest University Baptist Medical Center researchers reported today at an American Heart Association meeting in Santa Fe, NM.
John R. Crouse III, M.D., professor of internal medicine (endocrinology/metabolism) and public health sciences (epidemiology), said the project was the first to dissect the effects of isoflavones in soy from the overall soybean.
Crouse and his colleagues studied 156 patients with moderately elevated cholesterol levels who were randomly assigned to receive a soy drink containing soy protein either with or without isoflavones. Another group of patients got a beverage containing casein, the principal protein of cow's milk, but no soy protein or isoflavones.
Soy drinks containing isoflavones reduced both total cholesterol and low-density lipoproteins, LDL, the so-called bad cholesterol, said Crouse. In patients who started with a high LDL cholesterol, the effect was even more dramatic -- a 10 percent reduction in just nine weeks. Soy protein from which isoflavones were removed by alcohol extraction had no such effect.
"The conclusion is that the active ingredient in soy is the isoflavones," Crouse told the AHA's 38th Annual Conference of Cardiovascular Disease, Epidemiology and Prevention.
Scientists have long known that cardiovascular deaths and illnesses were lower in people who lived in the Far East than in Western countries. They suspected that the soybean might be part of the difference, since soy consumption is high in the Pacific Rim countries and uncommon in the West. Naturally occurring soy contains high concentrations of isoflavones, also known as phytoestrogens.
Studies in monkeys, mostly conducted at Wake Forest, showed that soy
containing these phytoestrogens had many of the same benefits as the standard
Contact: Robert Conn, Mark Wright or Jim Steele
Wake Forest University Baptist Medical Center