Soy Isoflavin & Menopause
Soybeans are known to be healthful, especially when consumed in their natural state, as in edamame (soybeans harvested in the green stage) or fermented, which is the process used to create tempeh and miso. Soy products' most significant health benefits seem to be derived from isoflavones, a class of naturally occurring organic compounds that may act as phytoestrogens, plant-based chemicals very similar to the hormone estrogen. Eating natural soy products may be beneficial to women as a way to help combat loss of estrogen and counteract symptoms like hot flashes, night sweats and loss of bone density during menopause.
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Isoflavones
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Two of the primary soy isoflavones are genistein and daidzein. They are found in foods made from whole soybeans, and they may also be ingredients in many supplements that claim to be beneficial for women during and after menopause.
Studies present conflicting results as to whether the isoflavones themselves provide benefits or if it is something else found in soy that is advantageous. Some studies of various purported health benefits of soy and soy products have not found any proof of positive effects. In fact, some research has reported that isoflavones may inhibit thyroid function or increase the risks of breast cancer in some women.
Estrogens and Antiestrogens
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Though theories are speculative, isoflavones have potentially contradictory effects, acting both as estrogens and as antiestrogens. In premenopausal women who have high hormone levels, they may act as antiestrogens, blocking some effects of estrogen and possibly protecting against breast cancer. But after menopause, when estrogen levels are lower, they may act like estrogens, thus relieving hot flashes and other symptoms.
What effect concentrated isoflavones have is unclear, and that is problematic. If your body experiences an estrogen-boosting effect when you wanted an estrogen-blocking effect, you could end up increasing your risk of breast cancer. These complexities are seldom mentioned by advocates of soy products and supplements.
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Soy Supplements
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Amounts of isoflavones in soy supplements are not regulated, so they vary quite a bit. Some pills contain such small amounts that they probably have no effect at all, and some have much more, or much less, than the label states. No one knows how much a woman needs to get a beneficial result (if there is one), nor what amount would be too much and thus potentially unhealthy. No one knows what the long-term effects of supplements containing concentrated isoflavones will be.
Manufacturers and marketers of soy supplements seldom if ever mention possible adverse effects of soy isoflavones. Even if you did know the contents of the pills, you don't know what they would do in your body. They do know that isolated isoflavones may trigger unpredictable hormonal actions, which can be risky.
Soy and Bone Strength
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Consuming soy products has been tied into bone strength. For example, one study found that women who included at least 13 grams of soy milk or food containing soy isoflavones in their daily diet were much less likely to suffer a bone fracture than women who consumed less (www.ncbi.nlm.nih.gov/pubmed/16157834). Another study found that women who drank two glasses of soy milk daily had reduced lumbar spine bone loss compared to those who did not drink soy milk (www.ncbi.nlm.nih.gov/pubmed/15309425?log$=activity).
Soy and Hot Flashes
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Whole soy consumption is higher in Japan, China and other Asian countries than in Western countries. Research shows that while more than 80 percent of North American women suffer from hot flashes, the number in Asian countries is more like 30 percent.
To find ways to add soy products to their diets, some women in the United States and other Western countries have turned to traditional Asian foods made from soybeans rather than relying on questionable supplements. Although there is not enough evidence to prove that soy foods ease menopausal symptoms, research suggests that women who have frequent hot flashes may experience relief from eating soy products.
Whole Soy Foods
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Soybeans are legumes and are especially rich in isoflavones. In addition to the healing power of isoflavones, soy is high in antioxidants, omega-3's and protein.
There is a difference between isolated soy compounds, soy supplements and whole soy foods containing natural phytonutrients or isoflavones. The inconsistencies in supplements are not a problem with natural and organic soy foods, which may be worth adding to one's diet for their various health benefits unless soy allergies are present.
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References
Resources
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