The factors involved in the development of prostate cancer are complex. From the known high-risk factors, diet can trigger prostate cancer. Studies have shown that excessive intake of fatty foods can increase the prevalence of prostate cancer, while a soy protein-based diet can reduce its incidence. The incidence of prostate cancer among Chinese and Japanese immigrants in San Francisco is 37 times higher than that of their native counterparts, and one important factor is that they eat more fatty foods than their native counterparts. This is because excessive fat intake leads to increased cholesterol synthesis, which further leads to increased cholesterol-based synthesis of androgens, and the increased rate of testosterone in androgens is an important factor in the development of prostate cancer. Meat, especially red meat, such as beef, lamb, pork and fat, or processed meat, such as sausage, smoked sausage, cured meat, ham, canned meat, grilled, roasted, fried meat, etc. can increase the incidence of prostate cancer. For this reason, the World Cancer Research Fund recommends that if a diet cannot be devoid of red meat, it should provide less than 10% of the total daily intake of calories. The recommendation for individual diets is to limit the amount of red meat consumed to less than 80 grams per day. Soybeans are rich in phytoestrogens that disable tumor-inducing hormones, especially the lignans that have been shown to block prostate cancer growth in experimental studies. High intake of selenium and vitamin E may reduce the risk of prostate cancer. Vitamin E is known to be an effective antioxidant against many tumors, and nuts (such as walnuts, almonds, cashews, hazelnuts, etc.) are the best source of natural vitamin E, which is much more active than synthetic vitamin E. In addition, components such as catechol in green tea or vitamin E with selenium in fresh vegetables and fruits can inhibit the development of prostate cancer. The diet to prevent prostate cancer is summarized in five points: first, the ratio of fat in the total calories of food is less than 20%; second, the daily intake of soy foods 2040 grams; third, selenium 200 micrograms per day; fourth, vitamin E 400800 international units per day; fifth, drink more green tea. Three or four of these two can also be used to often eat more fresh vegetables and fruits instead.