Soy Intake and Cholesterol.




Journal of Nutrition

Related Monographs

Consumer Data: Soy Isoflavones Hyperlipidemia
Professional Data: Soy Isoflavones Hyperlipidemia


Scientists classify soy isoflavones from the plant Glycine max as phytoestrogens. Phyto is a Greek root word meaning plant, so phytoestrogens are plant-based compounds that have estrogen-like activity. Because they are structurally similar to estrogens, isoflavones exert weak estrogenic activity. Because of their estrogen-like effects, isoflavones have been studied for a wide spectrum of health benefits.

Soybeans and soy foods like tofu are the best dietary source of isoflavones. However, many soy protein concentrates and soy products processed with alcohol may not contain isoflavones. A synthetically derived form of isoflavones, known as ipriflavone, is also available.

Isoflavones may also support cardiovascular health through a variety of mechanisms. It may help lower cholesterol. A recent study reviewed 8 studies involving soy isoflavone intake and its effects on cholesterol levels. This study, published in the Journal of Nutrition, found that participants in these studies had similar dietary fat, cholesterol, and fiber intake. Those who consumed an average of 50 grams of soy protein isolate with a content of 96 mg of isoflavones decreased their serum LDL cholesterol levels while those who consumed lower amounts of isoflavones did not see the same results. The authors concluded in this review that, “With identical soy protein intake, high isoflavone intake led to significantly greater decreases in serum LDL cholesterol than low isoflavone intake, demonstrating that isoflavones have LDL cholesterol–lowering effects independent of soy protein.”1


1. Zhuo XG, et al. Soy Isoflavone Intake Lowers Serum LDL Cholesterol: A Meta-Analysis of 8 Randomized Controlled Trials in Humans. Nutrition. Sep 2004. J. Nutr. 134:2395-2400.