The incidence and mortality rate of breast cancer is high in some western countries, and in some cases, it is the second most common cancer among women after lung cancer. In Asia, such as China and Japan, the incidence of breast cancer is low, for example, the mortality rate of breast cancer in the United States from 1987 to 1991 was 27.2 per 100,000, second only to lung cancer with a mortality rate of 30.5 per 100,000. In China, the breast cancer mortality rate was 2.93 per 100,000 from 1990 to 1992, which was the eighth highest. However, in recent years, the incidence rate of female breast cancer in large cities such as Beijing is only slightly lower than that of lung cancer and ranks second. The results of epidemiological surveys and analyses suggest that the consumption of soy in China and Asian countries such as Japan is 20 times higher than that in Western countries such as the United States. The low incidence of breast cancer in women is related to the protective effects of phytoestrogens in soy, the most important of which are soy isoflavones. The U.S. National Cancer Institute began studying the anti-cancer effects of soy, especially its soy isoflavones, in 1991. In 1985, a total of 12 papers on soy isoflavones were published throughout the year, while now there are more than 600 scientific papers on the subject a year. A recent experiment using female monkeys published in a foreign journal in July 2004 concluded that soy is safe for breast cancer and that soy isoflavones do not increase the risk of breast cancer and do not cause breast cell hyperplasia. The experiment was observed for 3 years and the daily dose of soy isoflavones was 129 mg, which is much higher than the amount contained in a typical diet rich in soy products. What is soy isoflavone? It is a phytoestrogen, which is similar to estrogen in structure and molecular weight. It selectively binds to estrogen receptors, and it has a two-way regulatory effect on estrogen in women. When estrogen levels in the body are low, it plays the role of estrogen supplementation, and estrogen can only have an effect if it binds to the receptor; while when estrogen levels in the body are high, the excessive effect of estrogen is prevented by soy isoflavones binding to the receptor. Soy isoflavones are very narrowly distributed in the plant world, and the main dietary source is soy. Not only do soy isoflavones reduce the risk of breast cancer, but they have also been reported to reduce the risk of prostate cancer, lower blood cholesterol, coronary heart disease, stroke, osteoporosis and other diseases. Since soy isoflavones have so many benefits for women’s health and for breast cancer prevention, why is it still said that soy products should be consumed with caution for breast cancer? This is because some people believe that breast cancer is an estrogen-dependent tumor, and that hormone replacement therapy for postmenopausal women increases the incidence of breast cancer, endometrial cancer, coronary heart disease, venous thromboembolism and other diseases. And although soy isoflavones are structurally similar to estrogen, their effects in the body are different. A large number of epidemiological surveys, animal experiments, in vitro experiments on cells, etc., the results of which are that women should be encouraged to eat soy products rich in soy isoflavones, which are considered to have only benefits, but no harmful effects. In 1999, the U.S. Food and Drug Administration recommended 25 grams of soy protein per day as a cholesterol-lowering dietary supplement for people with hypercholesterolemia. This is a high amount, equivalent to half of a woman’s daily protein intake and two and a half times the average daily soy protein intake of the Japanese. A more appropriate dose, some consider 15 grams per day, or 10-25 grams, equivalent to 50 mg of soy isoflavones (in glycosidic ligand amounts), with a range of 30-100 mg. 15 grams of soy protein is primarily used as a substitute for animal protein. Soy protein is a good quality, complete protein, but does not contain cholesterol, has significantly less saturated fatty acids and significantly more unsaturated fatty acids than animal protein, all of which are beneficial in the prevention of cardiovascular and cerebrovascular disease. In the United States, due to media coverage of these scientific findings over the past 10 years, which have been recognized by American consumers, sales of soy products in the U.S. market have increased threefold. China is the homeland of soybeans, early to soy as a food crop. Soybeans can be used for both food and oil. Chinese medicine believes that soybeans have “wide in the lower gas, large intestine, eliminate swelling and poison” effect. Soybean can be processed into hundreds of soybean products, commonly eaten tofu, tofu shreds, dried tofu, bean sprouts, soy milk, tofu brain, curd, etc.. There are also many types of soybean meals, each with its own benefits. The U.S. recommended 15 grams of soy protein per day, 10-25 grams converted into raw soy is 42 grams, 28-70 grams converted into tofu is about 185 grams per day, 123-308 grams, or 2 1/2-6 more than two taels of tofu per day. The daily intake of beans and soy products in the balanced dietary pagoda recommended by the Chinese Nutrition Society is 40 grams of raw soybeans, which is almost the same as the daily amount of 15 grams of soy protein. We hope that women in China will eat soy products with confidence, which according to available information is beneficial and harmless to women’s health and to the prevention of breast cancer.