Soy and its effects on cholesterol in men.




J Am Coll Nutr

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. 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 have been studied for a wide spectrum of health benefits, including effects on cholesterol.

Cholesterol has received a great deal of press, and medical experts agree that high blood cholesterol is a risk factor for heart disease. But cholesterol is not an enemy. The body needs cholesterol and manufactures its own supply. Essential for life, cholesterol plays many important roles. Cholesterol, along with other fats, is a key component of cells membranes. The body uses cholesterol as the building material for hormones such as estrogen and testosterone. Bile salts, which break the fat we eat into small particles that can be digested, are composed largely of cholesterol. Cholesterol is our friend, something the body requires, in the right places and amounts.

A study conducted in Scotland recruited 61 men with high blood pressure and or high cholesterol. These men were placed on a diet containing at least 20 grams of soy protein (with 80 mg of isoflavones) or a placebo diet. After this five-week diet, researchers found that those on the soy diet had lower systolic and diastolic blood pressure. Total cholesterol levels had also decreased in this group. Since high blood pressure and cholesterol are both risk factors for cardiovascular disease, the authors concluded that 20 grams of soy protein for five weeks could help reduce these risk factors among men.1


1. Sagara M, et al. Effect of Dietary Intake of Soy Protein and Isoflavones on Cardiovascular Disease Risk Factors in High Risk Middle-Aged Men in Scotland. J Am Coll Nutr. Mar 2004;21(1):85-91.