Soy Protein and Cardiovascular Disease A Statement for Healthcare Professionals From the Nutrition Committee of the AHA

Cardiovascular disease (CVD) is the leading cause of death in the United States.1 Diet has a major impact on several modifiable risk factors for heart disease: hypercholesterolemia, hypertriglyceridemia, elevated LDL cholesterol, low HDL cholesterol, hypertension, obesity, and diabetes. The recommended low-saturated-fat, lowcholesterol diet1 does help lower risk of CVD.2,3 However, other dietary factors may offer additional benefits. There is increasing evidence that consumption of soy protein in place of animal protein lowers blood cholesterol levels and may provide other cardiovascular benefits. Epidemiologists have long noted that Asian populations who consume soy foods as a dietary staple have a lower incidence of CVD than those who consume a typical Western diet.4 Soy protein consumption in Japan is reported to be as much as 55 g/d,5 compared with ,5 g/d in the United States.6 In 1998, deaths from CVD per 100 000 people between the ages of 35 and 74 years were as follows: 401 for US men, 201 for Japanese men, 197 for US women, and 99 for Japanese women.1 There are many differences in dietary patterns and lifestyle factors that could account for differences in disease patterns among countries. The American Heart Association (AHA) Dietary Guidelines for Healthy American Adults2 stated that although there was some evidence that when soy protein was substituted for animal protein, total and LDL cholesterol could be reduced, the findings were inconclusive. The AHA Nutrition Committee concluded that the use of soy foods was consistent with the AHA Dietary Guidelines, but no recommendation was made to include soy protein in the diet. More research on the mechanisms explaining the effects of soy protein and related phytochemicals on blood lipids was recommended. This AHA Science Advisory provides an update on recent research reports. The following description is from the Food and Drug Administration (FDA).7 Soy protein is an edible component of the soybean, Glycine max. Soy protein is produced from raw whole soybeans by a multistep process that removes the lipid and indigestible components to concentrate the protein and increase its availability. Depending on the particular steps used during processing, soy protein ingredients may take the form of isolated soy protein (ISP), soy protein concentrate, or soy flour. Each ingredient may be further processed into texturized soy protein or texturized vegetable protein (TVP) used in the manufacture of meat and poultry analogues by thermoplastic extrusion or steam texturization to impart structure and shape. In addition to protein, these soy protein ingredients contain other naturally occurring soy constituents, such as isoflavones, fiber, and saponins. The specific processing steps that are used determine the extent of retention of naturally occurring components in the final product. Soy protein is also consumed as a component of traditional fermented and nonfermented soy foods, such as tofu, tempeh, and miso, as well as whole soybeans, soynuts, soymilk, soy yogurt, and soy cheese. These products contain variable amounts of soy protein and other naturally occurring soy constituents depending on the specific technologies used in these products. Soy protein ingredients and soy protein– containing foods may partially replace or be used in addition to animal or other vegetable protein sources in the human diet.