Many people like to drink self-milled soy milk, but many people worry that women drinking soy milk all year round will lead to breast cancer because soy products contain a lot of phytoestrogens (mainly soy isoflavones), and the unabsorbed phytoestrogens will accumulate in the body, causing high estrogen in the human body and increasing the chances of breast cancer. This is actually a misconception! There are many types of estrogens, such as animal estrogens, phytoestrogens and synthetic estrogens, as well as those organic environmental pollutants that have estrogen-like effects, among which phytoestrogens are the beneficial estrogens for humans. Soy Isoflavones Reduce Breast Cancer Epidemiological studies have long proven that the incidence and mortality rates of breast and prostate cancers in China and other Asian countries are lower than those of Westerners, related to the Asian diet of consuming large amounts of soy and soy products. The diets of European and American countries generally do not contain soy and soy products, and soy isoflavones are consumed in disproportionately low amounts. A scholar studied 5,042 female breast cancer patients aged 20 to 75 in Shanghai and found that eating soy products significantly reduced the recurrence and mortality rates of breast cancer patients, and the results of this study were published in 2009 in JAMA, an authoritative American medical journal. A case-control study of diet and breast cancer in Chinese women living in Singapore also showed that soy had a significant preventive effect on the development of breast cancer. Results from Japanese studies also showed that Japanese women who regularly consumed probiotic beverages containing soy isoflavones since adolescence had a reduced incidence of breast cancer.In an epidemiological study of soy isoflavone intake and risk of breast cancer among women in Takayama, Japan, Professor Wada et al. found that women with higher intakes of soy and soy products had a relatively lower risk of breast cancer before menopause; also that An article published in the British Journal of Cancer in 2008 also concluded that isoflavones in soy not only do not increase the risk of breast cancer, but also reduce the prevalence of breast cancer, especially in Asian populations with high consumption of soy-based foods. Although some pure soy isoflavones have been found to promote tumor growth in some in vitro cell lines and animal studies. However, soy has not been shown to cause cancer. Because of the wide variety of phytoestrogenic isoflavones in soy, it is not unusual for them, as monomers, to exhibit partial stimulation and partial inhibition of cancer cells. Moreover, humans and animals differ in the effects of isoflavones, and the effects of dietary soy and experimental isoflavones are equally different. Phytoestrogens have a bi-directional balancing effect Phytoestrogens not only counteract the excess of harmful estrogens in the body, but also have a substitution effect when the human physiological estrogens are insufficient, which is the “bi-directional regulation” of estrogenic effects, avoiding harmful stimulation and ensuring the normal physiology of the body. Recent studies have shown that this bidirectional balancing effect of soy isoflavones on estrogen can significantly affect estrogen-related tumorigenesis. When genistein (a component of soy isoflavones) and estrogen act simultaneously on target organs in vivo, the two can competitively bind estrogen receptors in the body, thereby significantly reducing the incidence of estrogen-associated tumors. And when estrogen levels in the body are too high, soy isoflavones exhibit an anti-estrogenic effect. In addition to its preventive effect on breast cancer, soy isoflavones can also alleviate female menopausal syndrome, prevent osteoporosis and cardiovascular disease. This shows that there is no scientific basis for the claim that “women who drink soy milk all year round will cause breast cancer”, and that long-term, moderate consumption of soy foods or crude products can effectively prevent the occurrence of breast cancer and cardiovascular disease.