The effects of soy protein containing isoflavones on blood lipids

It is well known that soy protein has a beneficial effect on blood lipids, but it has been unclear which components of soy protein are responsible for the health benefits. A new meta-analysis of 23 controlled trials, published in the February 9, 2005 American Journal of Clinical Nutrition, aimed to identify and quantify the effects of soy protein containing isoflavones on blood lipids.

The results of this study show that soy protein containing intact isoflavones significantly reduced total cholesterol by 3.77%, LDL cholesterol by 5.25% and triglycerides by 7.27%. In studies greater than twelve weeks in duration, beneficial HDL cholesterol was increased by over 3%. These changes were related to the level and duration of intake, gender, and initial serum lipid concentrations of the subjects. Whereas soy protein containing isoflavones had significant positive effects on blood lipids, researchers found that tablets containing only extracted soy isoflavones did not have the same effect on total cholesterol reduction.