There is no denying that soy is a nutrition powerhouse. But what has researchers intrigued these days is not soy's nutrient density as much as its phytoestrogen profile, particularly its isoflavones and their potential impact on women's midlife health. The two primary isoflavones in soy are genistein and daidzein.
Heart Health. Research demonstrates that soy protein decreases LDL cholesterol, soy's most well-documented effect, and tends to increase HDL cholesterol. Soy isoflavones also have antioxidant properties that protect LDL cholesterol from oxidation. The soy isoflavone genistein also may increase the flexibility of blood vessels.
Bone Health. The role of soy in reducing osteoporosis risk comprises a relatively new and promising area of research. A primary motivator for studying the impact of soy on bone health is that soy isoflavones are similar to synthetic estrogens like tamoxifen and ipriflavone, which have been shown to be effective in preventing or reducing bone loss.
Menopausal Health. The role of soy in reducing peri- and postmenopausal symptoms is one of the newest areas of research related to soy and health. Epidemiological data indicates that Asian women report lower levels of hot flashes and night sweats compared to Western women. One recent study showed that 60 g of soy protein isolate added to the daily diet substantially reduced the frequency of hot flashes in some postmenopausal women.
Although phytoestrogens pills are available, no one really knows how beneficial they are, nor is it certain if such pills are safe. Many foods containing phytoestrogens, however, have been consumed safely for centuries. A soy beverage for breakfast. Soy milk in coffee. A handful of roasted soy nuts as a snack. A couple tablespoons of soy protein in a glass of juice. These options offer somewhere between 10 g to 30 g of soy protein and 20 mg to 60 mg of isoflavones.
Susan Calvert Finn, PhD, RD, FADA, is director of the Nutrition Services Department Ross Products Division, Abbott Laboratories. Abbott Laboratories is a member of the Healthcare Leadership Council.
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