In 1999, the US Food and Drug Administration approved labeling of soy protein as effective against coronary heart disease. The conclusion to recommend the health benefits of soy was based on information that at least 25 g/day of soy protein had been demonstrated to reduce LDL and total cholesterol. The suggestion was that the intake of 6.25 of soy protein per serving 4 times daily would achieve this condition. The same FDA statement reminded that soy isoflavones were not founded to be critical for the cholesterol-lowering benefits of soy protein.

Since this FDA report, there has been a significant amount of research targeting the health effects of both soy isoflavones and protein.

Based on reviews of 22 randomized trials comparing use of isolated soy proteins with other proteins, the American Heart Association (AHA) nutrition committee recently concluded in a report published in the 2005, January 17 Rapid Access issue of Circulation, that there is not a benefit from soy. By consequence, AHA does not recommend isoflavone supplements in food or pills.

The AHA nutrition committee reveals that from 22 total reviewed studies, in 19 studies there was no evidence regarding effect on LDL cholesterol or on other lipid risk factors. The panel also noted no demonstrated positive effect on vasomotor symptoms of menopause or related to slowing postmenopausal bone loss. Similarly, there is insufficient evidence to recommend soy isoflavones for prevention or treatment of breast, endometrial or prostate cancer.

However, the study authors recommend consumption of foods containing soy, as they generally have high contents of polyunsaturated fats, fiber, and vitamins.