Environmental estrogens refer to environmental chemicals with estrogen-like effects, which mimic or interfere with the physiological and biochemical actions of natural estrogens. Currently, environmental estrogens are mainly classified into five categories, among which phytoestrogens are receiving increasing attention for their benefits to human health. Phytoestrogens, such as isoflavones, are beneficial plant estrogens that are structurally similar to estradiol. The main dietary source of isoflavones is soy and its products, such as soybean powder. Soy isoflavones have a preventive effect on hormone-related diseases:
（1）Cancer
Soy isoflavones have a significant preventive and therapeutic effect on the occurrence and development of breast cancer, prostate cancer, and some other cancers. Comparative studies have shown that the higher the intake of soy products and isoflavones in a population, the lower the incidence of these cancers. Soy has a significant preventive effect on the occurrence of breast cancer in premenopausal women.
（2）Menopausal Syndrome
Hot flashes and vaginitis in menopausal women are caused by the decline of ovarian function. Therefore, using soy phytoestrogens for hormone replacement therapy to supplement the body's phytoestrogens can promote vaginal cell proliferation.
（3）Cardiovascular Disease
Consuming 40 grams of soy protein daily, containing moderate to high levels of isoflavones, for 6 months can reduce the risk of cardiovascular disease in postmenopausal women. Another study found that people with high cholesterol levels who consumed an average of 47 grams of soy protein per day had a 9% reduction in total cholesterol and a 13% reduction in low-density lipoprotein levels. This effect may be related to soy phytoestrogens.
（4）Osteoporosis
If women adopt hormone replacement therapy in the few years before clinical menopause, it can prevent bone loss until at least age 75. Animal experiments have confirmed that soy protein can increase bone formation. Reports on human subjects have also confirmed that soy protein can increase bone density in the short term.