Cardiovascular Benefits
of Soy Protein

One of the best sources for protein is soy protein. It is a complete protein and has properties that have been shown to improve heart and vascular health. Soybeans are a great source of the phytoestrogens daidzein, genistein, and glycitein. Phytoestrogens are estrogenlike substances found in plants. These soy phytoestrogens are also called isoflavones, and have been shown to have many different benefits. They help in reducing symptoms of menopause, such as hot flashes; and they may provide protection against prostate and certain breast cancers. There are also a number of benefits that isoflavones provide for the cardiovascular system. The one drawback for soy products is that they contain a fair amount of oxalate, which increases calcium excretion in the urine. Spinach, rhubarb, and beet greens also contain similar amounts of oxalate, and so if you have kidney stones, soy products and these vegetables should only be eaten in limited quantities.

There is a significant amount of research that shows people who consume higher quantities of plants containing phytoestrogens have fewer incidents of heart attacks and strokes, as well as reduced rates of cardiovascular disease risk factors. Japanese people have half the cardiovascular disease than Americans, and soy is certainly deserves some of the credit. Soybeans are high in fiber and low in fat and contain many phytonutrients, which act as antioxidants and interfere with the oxidation of blood fats. This prevents free radicals from forming and causing damage to the endothelium, which in turns protects nitric oxide production.

In 2001, scientists at the University of Milano in Italy wrote, "The soybean diet is the most potent dietary tool for hypercholesterolemia (high cholesterol levels)." In Current Atherosclerosis Reports, they looked at several hypotheses that explained how soy may reduce cholesterol levels, including the high levels of phytoestrogens, the fiber in soy, and the soy protein itself. Researchers at the University of Kentucky reviewed 38 studies that looked at the influence of protein from soy on cholesterol levels in 740 men and women. The New England Journal of Medicine published the results which showed that those people who ate an average of 47 grams per day of soy protein, rather than animal protein, had a drop in total cholesterol of 9.3 percent, LDL cholesterol declined 12.9 percent, and triglycerides fell 10.5 percent. In conjunction, HDL cholesterol levels climbed 2.4 percent, although this was not statistically significant.

In studies by John P. Cooke at Stanford University, they found that people who took capsules containing 50 milligrams of phytoestrogens (a mixture of purified daidzen and genistein, with a small amount of glycitein) daily, had significantly improved vasodilation. This was equivalent to 50 grams of soy protein. Phytoestrogens are milder than estrogen, having only approximately 1/1000th the activity of estrogen, however, a diet high in soy protein can raise phytoestrogen levels in the blood to a point where they benefit cardiovascular health.

Some good sources for adding soy into your diet are whole soy yogurt, which tastes great, and soy milk. Other sources are miso soup, roasted soy nuts, tempeh, soy flour, tofu, and soy burgers and franks. Teriyaki salmon, sushi, and sashimi are also good sources, as well as edamame (soybeans in the pod), which has become a popular snack in many sushi restaurants. It can be purchased frozen in most health food stores.

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