Numerous studies have found that soy lowers cholesterol levels and reduces the risk of coronary artery disease. Now a new report also ties soy to improved functioning of the arteries.

A group of 20 men with high cholesterol participated in this study. They were given a diet that provided 25% to 30% of energy from fats, 10% to 12% from protein, and the rest from carbohydrates. Soy protein was substituted for 60% of the animal source proteins in their traditional diets. Soy products were in the form of soy flour, soybeans, and soybean sprouts. Total fat intake was similar, but polyunsaturated fats replaced much of the saturated fats in the test diet. The diets provided 1845 calories/day.

After 6 weeks, total cholesterol, LDL ("the bad") cholesterol, and triglycerides decreased significantly. HDL ("the good") cholesterol levels were not affected. Those with the highest cholesterol levels at the start of the diet period had the greatest decreases, with a 21% reduction in those individuals whose baseline reading was more than 271 mg/dl.

The researchers also used ultrasound to assess how well the arteries dilate when blood flow is increased, a measure called "endothelial functioning." A decrease in endothelial functioning is the first step in the formation of plaque. In this study, the soy diet also significantly improved endothelial function. The authors of the report note that the benefits seen were probably related to both the soy diet and the cholesterol-lowering effects of the diet.

In the next few weeks, we'll look at soy substitutes that are easy to incorporate into your diet.

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