Epidemiological studies have found that the low incidence of breast cancer in Asian women is associated with the consumption of phytoestrogen-rich diets, which has led to widespread interest in phytoestrogens. Phytoestrogens are broadly defined as a group of plant components with biological activity similar to that of human estrogens, and their structure is similar to that of natural endogenous estrogens. Thus, phytoestrogens can attach to estrogen receptors and exhibit weak hormone-like properties, with potency ranging from one thousandth to several hundred thousandth of that of synthetic estrogens. Among the relationships between breast cancer and dietary factors, the intake of dietary fiber has received much attention and its preventive effect on breast cancer is relatively certain. Dietary fiber reduces the production of β-glucuronidase by intestinal flora, which can interfere with the enterohepatic circulation of estrogen, thereby reducing plasma estrogen levels and achieving breast cancer prevention. Some scholars believe that this effect of dietary fiber may also be related to phytoestrogens, as fiber-rich foods are also often sources of lignans (a type of phytoestrogen). Phytoestrogens may play a role in breast cancer prevention by inhibiting gonadotropin excretion and prolonging the follicular phase of the menstrual cycle. Research results show that phytoestrogens also have the following effects: (1) prevention of menopausal symptoms, (2) prevention of cardiovascular diseases, (3) reduction of osteoporosis during menopause, (4) prevention of estrogen-related tumors, (5) anti-Alzheimer’s effects, (6) antibacterial and anti-inflammatory effects, (7) anti-hemolytic effects, (8) regulation of body immunity, and (9) anti-radiation effects. Phytoestrogens are broadly divided into several categories: isoflavones, lignans, stilbene, coumarin estrogens and fungi, the most common ones being isoflavones and lignans. 1, isoflavones class recommended soy, preferably soybean milk or soybean sprouts. Isoflavones are water-soluble nutrients, so in the processing of soybean products will lose a lot with the pressing and de-watering process, while soy milk retains all the isoflavone substances. Sprouting increases the amount of isoflavone substances in soybeans by about two times. Other food sources rich in isoflavones include watermelon, papaya, hollowed out vegetables, carrots, string beans, chickpeas, bananas, etc. 2, lignans recommended flaxseed and sesame, preferably flaxseed powder and sesame paste. Many grains contain lignans, lignans in flaxseed content is about 1-4%, the content is much higher than other known plants, the general statement is 75-800 times higher. In addition, sesame seeds, oil seeds, fennel are also lignan-rich foods. Flaxseed oil and sesame oil remove the dietary fiber portion, which also removes most of the lignans, so it is advisable to consume ground flaxseed and sesame seed paste. Cereals, fruits and vegetables also contain lignans, such as barley, wheat, celery, pears, coffee, garlic, etc. 3, Stilbene recommended foods in grapes, red wine and peanuts. In addition, it is common in He Shou Wu, rhubarb, tiger scepter, goldfinch root and other herbs. 4, coumarin estrogens. Coumar estrogens only exist in alfalfa or alfalfa, clover and some beans, bean sprouts, at present, we do not know enough about them. 5.Fungal estrogens. In 1962, the discovery of a-zearalanol opened the research on fungal phytoestrogens. So far, it has been extracted from such as wheat, cotton, sugar beets in its oxidation products. Recommended daily intake of soy and flaxseed: Among the phytoestrogen-rich foods, isoflavonoid-rich soybeans, soybean sprouts, and lignan-rich flaxseed powder and sesame are the most recommended phytoestrogen-rich foods. Soybean is about 40 grams per day and flaxseed powder is about 5-20 grams per day.