Soybeans contain all of the essential amino acids necessary for human nutrition. Soy protein is a great substitute for high fat-animal proteins. Replacing these fatty proteins with soy will help lower levels of total cholesterol, low-density lipoproteins, and triglycerides; may improve menopausal hot flashes; may help lose weight; and may help maintain bone density and decrease fractures in postmenopausal women. Whole soy protein has superior results compared to isolated soy components.
Soy in the diet
Soy is a main staple of Asian diets (10-15 times more than the U.S.), and research has shown these populations have a lower risk of breast and prostate cancers. One explanation is that some cancers have a strong link to estrogen receptors, and soy contains isoflavones which act on these receptors and act as modulators. These isoflavones also bind to estrogen receptors in the brain, and can help reduce menopausal hot flashes. One study showed that woman taking 25g of soy protein and 101g of isoflavones daily, reduced hot flashes by over 40% compared to the control group (lifestyle changes only). Another study showed that woman who consumed over 90mg of isoflavones daily did not show attenuated bone loss, possibly helping prevent osteoporosis.
The FDA’s take on Soy
The FDA has claimed a diet that includes 25g of soy protein, and low in saturated fat and cholesterol, reduces the risk of heart disease. A product with this soy health claim must contain the following: at least 6.25 g of soy protein, less than 3 g of fat (less than 1 g saturated), less than 20 mg of cholesterol, and less than 480 mg of sodium.
Soy and the impact on estrogen
Research has found that estrogen helps with weight control. Estrogen increases metabolic rate and effective use of blood sugar. Menopause causes a significant reduction in estrogen which lowers metabolism and improper glucose use (increasing fat storage). Soy isoflavones act on the hypothalamus receptors similar to hormones like estrogen. As such, soy isoflavones can by studied as alternatives to hormone replacement therapy (HRT). The hypothalamus acts to regulate hunger, thirst, and fatigue, amongst many other actions. Soy isoflavones may be used for direct (controlling hunger and metabolism) and indirect (increasing energy and decreasing fatigue) weight control for the low estrogen states of menopausal women.
Soy in today’s food
Food-grade soy protein became available in 1959, and now can be seen used in a variety of foods like soups, cheeses, frozen deserts, cereals, pastas, and infant formulas. The FDA recommends 25g of soy protein daily for complete health benefits. Not only do the isoflavones in soy protein act on estrogen receptors, but also have antioxidant properties.