Soy Does Not Lower LDL Cholesterol

Lowering low-density lipoprotein cholesterol, even by a few points, reduces the risk of heart disease and stroke. Some studies found that substituting soy protein for animal protein lowered total and LDL cholesterol. Soy increases the activity of liver enzymes that break down cholesterol. In 1999, the FDA approved a claim from soy food manufacturers that a diet containing 25 grams of soy protein per day was good for the heart and lowered cholesterol. A year later, the American Heart Association recommended that people with a high risk of heart attack include soy products in their diets. Unfortunately, there was little solid evidence that soy was good for the heart or that it reduced blood cholesterol. Most studies showing positive effects used few subjects and often had statistical and research design problems. The American Heart Association changed its position in 2006 and concluded that soy protein or isoflavones (estrogen-like chemicals in soy) did not lower LDL cholesterol, triglycerides and blood pressure or increased HDL (the “good” cholesterol). Australian researchers confirmed this when they found that high soy protein intake had no effect on total or LDL cholesterol. However, substituting soy burgers and soy hot dogs for their high-saturated fat equivalents might reduce saturated fat intake and improve cardiovascular health. Even though soy foods don’t have a direct effect on cholesterol metabolism, they might improve the overall quality of the diet. (WebMD Health News, August 8, 2008; American Journal Clinical Nutrition, 88:298-304, 2008)