Premenopausal women have much higher circulating levels of estradiol-the major form of estrogen in the human body-than postmenopausal women. Because soy can have estrogenic properties, its effects can vary depending on the existing level of hormones in the body. Is it being examined in a study with animals or humans? Soy may be metabolized differently in animals, so the outcomes of animal studies may not be applicable to humans. Soy isoflavones and soy protein appear to have different actions in the body based on the following factors: The two major soy isoflavones are called genistein and daidzein.

Soy isoflavones can bind to estrogen receptors in the body and cause either weak estrogenic or anti-estrogenic activity. Soy is unique in that it contains a high concentration of isoflavones, a type of plant estrogen (phytoestrogen) that is similar in function to human estrogen but with much weaker effects. Part of the uncertainty is due to the intricacy of soy’s effects on the body. However, due to contrary research that suggests possible negative effects of soy in certain situations, there has been a hesitancy to wholeheartedly promote soy. As a species within the legume family, nutrition scientists often label soy as a food with potential for significant health benefits. Whether published in a popular press article or a well-designed clinical study, some debate about soy remains. Soy is exalted as a health food by some, with claims of taming hot flashes, warding off osteoporosis, and protecting against hormonal cancers like breast and prostate.Īt the same time, soy is shunned by others for fear that it may cause breast cancer, thyroid problems, and dementia, though these claims have not been substantiated. Soy is a nutrient-dense source of protein that can safely be consumed several times a week, and probably more often, and is likely to provide health benefits-especially when eaten as an alternative to red and processed meat.

Results of recent population studies suggest that soy has either a beneficial or neutral effect on various health conditions.

Studies may seem to present conflicting conclusions about soy, but this is largely due to the wide variation in how soy is studied. The Takeaway: Soy is a unique food that is widely studied for its estrogenic and anti-estrogenic effects on the body.

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