Soy Not as Good as Claimed

Published Online: Wednesday, March 1, 2006

According to the American Heart Association (AHA), tofu and other soy products may not do as much for cholesterol levels as was once thought. This statement may move FDA officials to rethink the agency's stand on the "heart healthy" claims soy product manufacturers are currently permitted to make. The findings were reported in the February edition of the AHA journal Circulation.

In a review of 22 clinical trials, researchers found that large amounts of isolated soy protein helped lower patients' low-density lipoprotein (LDL)—the "bad" cholesterol—by an average of only 3%. Soy supplements, such as isoflavones, proved even less effective. In 19 studies, the effect of isoflavones on LDL cholesterol was generally nil.

Earlier studies had suggested that diets rich in soy protein might help lower LDL levels and possibly raise high-density lipoprotein cholesterol levels. In 1999, the FDA allowed manufacturers of soy products to use "heart healthy" labeling. Based on these more recent trials, however, the AHA stated that there is no basis for recommending soy supplements. In fact, researchers did not find any special cholesterol advantage in soy protein, compared with other vegetable proteins.

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