Soy Protein not Beneficial in Lowering LDL

(Reuters Jan. 23, 2006)

DALLAS, - The American Heart Association has retreated precipitously from its previous strong endorsement of soy protein or isoflavones as beneficial in reducing cardiovascular risk factors. In a scientific statement issued today, updating one published in 2000, the AHA no longer endorses as “prudent” the addition of soy protein to a diet low in saturated fat and cholesterol. In its new statement, the AHA said it found no benefit for soy protein or isoflavones in lowering LDL cholesterol, improving HDL or triglycerides, or lowering of blood pressure.

The AHA’s new scientific statement, which was published in the Jan. 24 issue of Circulation, Journal of the American Heart Association, is based on an analysis of data from 22 randomized clinical trials. Nevertheless, the AHA said the jury is still out on the heart-healthy potential of soy food products like tofu, soy butter, soy nuts and soy burgers. Soy food products are low in saturated fats, and high in polyunsaturated fats, fiber, vitamins, and minerals -- all of which suggest that tofu and soy burgers could be important elements in a heart healthy diet. Soy products, the AHA said, could be used to replace foods that are high in saturate fats and cholesterol.

Frank M. Sacks, M.D., professor of nutrition at the Harvard School of Public Health and chair of the writing committee that drafted the statement for the AHA’s Nutrition Committee, said that the “big LDL-lowering effect from soy protein or isoflavones didn’t happen.”

People who consume large amounts of soy protein -- so much so that it makes up half of their daily protein intake -- are rewarded with only a 3% decline in LDL cholesterol. And the credit for the minimal benefit goes to soy protein itself, since the evidence suggests that isoflavones have no benefit at all. That slight blip in the LDL numbers is the best that soy can do. There was no evidence of benefit for HDL, triglycerides, or lipoprotein (a). Likewise, soy protein did not lower blood pressure.

The AHA, therefore, concluded that “the use of isoflavone supplements in food or pills is not recommended.” The AHA also found no evidence that soy protein and isoflavones could turn down the heat on hot flashes during menopause. Soy may slow postmenopausal bone loss, but the AHA review found only mixed results to back that claim. There was only no solid evidence that soy isoflavones could prevent or treat cancers of the breast, endometrium or prostate.

Primary source: Circulation Journal of the American Heart Associaiton

Source reference: Reference Sacks FM “Soy Protein, Isoflavones, and Cardiovascular Health A Statement for Professionals From the American Heart Association Nutrition Committee” Circulation 206; 113:& NA;-.