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Soy Proteins and Menopause In Japan, the majority of protein comes from soy, whereas in America -- with the exception of strict vegetarians -- most people obtain their protein from animal and cow's milk sources. Research has linked these dietary habits with the substantially lower occurrence of menopausal symptoms and related illnesses in Asian women. Japanese women, in fact, have been found to complain of the annoying night sweats and hot flashes associated with menopause only one third as often as their western counterparts. For this reason, the benefits of consuming soy protein have been the object of intense study in recent years, as scientists attempt to understand the workings of the plant.
Food products derived form the soybean, including soy flour, tofu, and soymilk, are a staple of oriental diets. Women of the orient consume an estimated 200 milligrams of soy daily. In contrast, American culture has long viewed soybeans as primarily a livestock feed crop. In the instances where it is an ingredient in American food, it is often processed to the extent that little of its nutritional value remains. Besides the economic benefits of plant-derived protein sources, there may be medical reasons to support the consumption of soy, especially for women. During the years that women menstruate, they produce high levels of the hormone estrogen. It is believed that the long-term exposure of the body (especially the cells of the breasts) puts women at increased risk for life-threatening diseases. When estrogen receptors located throughout the body's organs cease to receive the hormone, a potential pathway exists for dangerous chemicals to enter them and develop into diseases. Soy enters here into our discussion because its proteins contain two plant hormones, genistein and daidzein, phytoestrogens that mimic the behavior of human estrogen hormones. These hormones are believed to attach themselves to the body’s estrogen receptors, thus preventing the entrance of certain carcinogenic substances into organs. Preliminary evidence indicates that the body has numerous receptors that accept hormones differently, which can affect how a particular organ reacts to the phytoestrogens in soy. Although the process is not fully understood |
yet, there is promising data indicating that consuming soy proteins both before and after the onset of menopause can prevent illness and alleviate symptoms. Other tests have found that the effects of soy protein vary largely depending on a woman’s natural estrogen levels during consumption. For instance, it was discovered that menstruating women experienced little change or occasionally a drop in the amount of estrogen in their bodies, whereas menopausal women seemed to have more estrogen as a result of soy intake.
The belief is that soy proteins fight with existing estrogen in the body for access to estrogen receptors. There is an interesting theory about why soy and other phytoestrogen-producing plants like yams, brussel sprouts, and alfalfa, would make a hormone similar to human estrogen. The chemicals plants make usually serve a protective purpose, such as to deter predators. Scientists think that soy’s phytoestrogens are a defense mechanism, a way to decrease the fertility of animals that eat them. When there are less offspring of a predatory animal, the plant has a better chance of surviving. The unseen benefit of the plant’s behavior is that it counteracts the ill effects associated with the end of fertility. Besides inhibiting hot flashes and night sweats, soy protein offers other medically beneficial results. One is that it appears to lower levels of the "bad" cholesterol LDL. For yet unknown reasons, soy keeps the body’s cholesterol within a healthy range, which in turn decreases women’s chances of heart attack and stroke. Soy protein also seems to prevent the oxidation of LDL cholesterol, and its phytoestrogen genistein keeps smooth muscle cells from reproducing in the body. In combination, these affects create a strong decline in women’s chances of developing atherosclerosis, or hardening of the arteries. One such set of data appeared in 1998 when an Italian research group began administering a daily regulated dose of soy protein to a group of menopausal women. Each woman took sixty grams each day for a period of twelve weeks. Unfortunately, a quarter of the participants dropped out before the study was concluded. |
This was in part because of a holiday and in part because of unpleasant though minor side effects like constipation and gastrointestinal disturbances. However, the researchers found that the women taking soy protein experienced a rapid and continual drop in their symptoms throughout the life of the project. Between the third and twelfth weeks, participants reported that their hot flashes decreased from one-quarter to nearly one-half. Another potential benefit of regular consumption of soy proteins is weight maintenance. Unlike animal proteins, which have a relatively high level of cholesterol and saturated fat, soy has little fat and no cholesterol. Thus, the weight gain associated with menopause may be curtailed by adding soy to the diet. Because the phytoestrogen genistein prevents clotting, also symptomatic in menopause, it could further decrease the chances of stroke and heart attack in menopausal women. Estrogen encourages the maintenance of bone density in women, so when levels drop after menstruation, their bones can become more brittle. In fact, by the time women reach age 65, approximately one-fifth of them have experienced a fracture due to the decreased bone density of osteoporosis. Eating calcium-rich soy products during the reproductive years can strengthen bones against these breaks. Subsequently, it is believed (based on rat tests) that the phytoestrogens in soy can prevent bone degeneration. Although comprehensive studies have yet to be completed, the preliminary results of soy protein testing indicate that it can be an invaluable resource for menopausal women. From combating hot flashes and night sweats to providing protection against cancer, the possible uses of this readily available plant are encouraging. Given the evidence, it may be advisable for women to take advantage of this health-promoting plant throughout life and especially in the menopausal years.
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