The word phytoestrogens come from the Greek word “phyto,” or plant, and “estrogen,” the hormone that promotes female characteristics in the body.
A phytoestrogen is a naturally-occurring plant nutrient that exerts an estrogen-like action on the body. They are adaptogens that bind on the same cellular sites as do estrogens. On average, phytoestrogens have about two percent of the strength of estrogens. Therefore, when estrogen levels are high, substituting a phytoestrogen for an estrogen means that there will be much less estrogenic activity at a given binding site. Conversely, if estrogen levels are low and estrogen-binding sites are empty, filling them with phytoestrogens that contain two percent estrogen activity will result in a total increase in systemic estrogenic effect.
Asian populations have historically had lower rates of cardiovascular disease, menopausal symptoms, breast cancer (and other hormone dependent cancers), diabetes and obesity than Western population. Soy is the cornerstone of a traditional Asian diet, an observation which has long fueled the widely held belief that consumption of soy foods reduces the risk of disease.
Scientists have discovered hundreds of phytoestrogens including soybeans, whole grains, seeds (especially flax), nuts (especially walnuts) and many herbs. They are the bioflavonoids in the isoflavone family. Daidzein and genistein are primary phytoestrogens yet to be discovered.
Phytoestrogens have also been termed dietary estrogens because they’re not created by the human endocrine system. They can only be ingested or consumed. Health benefits of phytoestrogens include relief from menopausal symptoms and lowered risk of osteoporosis, heart disease, and breast cancer. Phytoestrogens appear to lower gonadotrophin levels, which will lengthen the menstrual cycle. Lower gonadotrophin levels reduce menopausal symptoms, such as hot flashes. When acting on estrogen receptors, phytoestrogens behave differently from estrogen and more like Selective Estrogen Receptor Modulators (SERMs). An example of a well-known SERM is the breast cancer treatment drug tamoxifen, which stimulates estrogen receptors in the uterus and bone, but suppresses them in the breast.
Unlike pharmaceutical estrogens, the phytoestrogens in food do not appear to increase the risk of endometrial cancer. However, since phytoestrogens act on hormone receptors within the reproductive system, they can behave like endocrine disruptors, with the potential for adverse effects. In conclusion, moderation is the key. phytoestrogens are beneficial in doses, particularly for women of older age.
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