Breast cancer is one of the most common malignant tumors in women. In the past 30 years, the incidence of breast cancer in China has been on the rise, and now it has become the first tumor in women. Dietary and nutritional factors are directly or indirectly related to the occurrence of tumors, therefore, it is especially important to pay attention to the prevention of tumor diet and nutrition. Obesity is an important risk factor for breast cancer. The results of an epidemiological survey involving 344,000 women show that BMI is positively correlated with the incidence of postmenopausal breast cancer, especially for those with abdominal obesity and higher waist-to-hip ratio (WHR); the pathogenesis is related to the increase of estradiol level and the change of inhibitory hormone binding protein concentration in obese people. It can be seen that weight loss and weight reduction are the first priority for breast cancer prevention. High-fat diet and breast cancer The high ratio of dietary fat to total energy has become a common nutritional problem in the diets of Chinese residents. Therefore, in order to prevent breast cancer, you should put less oil in your frying dishes, no matter it is animal oil or vegetable oil; also, you should pay attention to eat less fatty foods such as fatty meat, fried foods, pastries, peanuts and melon seeds. The food. In addition to reducing the total fat intake, the intake of saturated fatty acids from pigs, cows and sheep also increases the risk of breast cancer in postmenopausal women; on the contrary, a diet based on monounsaturated fatty acids such as olive oil and tea seed oil as cooking oil can reduce the risk of breast cancer by 13% to 34%; in addition, there is a negative correlation between the dietary intake of omega-3 fatty acids and the incidence of breast cancer, so it is recommended that In addition, dietary intake of omega-3 fatty acids is negatively correlated with breast cancer incidence, so it is recommended to consume seafood rich in omega-3 fatty acids, especially fatty sea fish. Alcohol, folic acid and breast cancer Alcohol can increase blood estrogen levels in pre- and post-menopausal women; acetaldehyde, a metabolite of alcohol, is a carcinogen, mutagen and tumor initiator; excessive alcohol accelerates the metabolism and loss of folic acid, which can lead to folic acid deficiency and promote cancer development. Some studies have reported that the risk of breast cancer increases with the amount of alcohol: women who consume 35-44g of alcohol daily have a 32% increased risk of breast cancer compared to women who do not consume alcohol, and those who consume more than 45g of alcohol daily have a 46% increased risk; for every 10g increase in the amount of alcohol, the risk of breast cancer increases by 9%. The cumulative breast cancer incidence rates for women aged 20 to 80 years in developed countries whose alcohol consumption was zero, 2, 4 and 6 drinks were 8.8%, 10.1%, 11.6% and 13.3%, respectively. Folic acid supplementation has also been reported to reduce the risk of breast cancer in women who consume more than 15 g/day of alcohol on a chronic basis. Phytoestrogens and breast cancer The molecular structure of phytoestrogen isoflavones is similar to that of animal estrogens, which has a bi-directional effect on human estrogen and the prevention of breast cancer; in addition, isoflavones have the function of inhibiting tyrosinase activity, anti-angiogenesis and induction of apoptosis, as well as the function of antioxidant and improving body immunity. Therefore, the moderate intake of soy and its products rich in isoflavones is beneficial to the prevention of breast cancer; this may also be one of the reasons why the incidence of breast cancer in American women is 4-7 times higher than that in Asian women. Since the mechanism of action of isoflavones is still unknown, high supplementation with phytoestrogens is premature as a preventive measure for breast cancer. Other foods and breast cancer The trimethylxanthine in coffee can stimulate the proliferation of breast tissue and cause breast pain, increasing the risk of cancer. Some domestic studies have shown that adequate intake of fresh vegetables and fruits is beneficial for breast cancer prevention. Diet and nutrition for breast cancer prevention: Reduce total calorie intake; control weight and prevent obesity, especially abdominal obesity; control total dietary fat, reduce saturated fatty acids and increase the proportion of monounsaturated fatty acids and omega-3 fatty acids; use tea seed oil and olive oil as the main cooking oil; do not drink alcohol or control alcohol intake less than 15g/day and pay attention to folic acid supplementation; moderate intake of soybean and its processed foods, but not recommended to supplement a large amount. Processed foods, but not recommended to supplement a large amount of isoflavones; reduce the intake of red meat and its processed food, especially barbecue, fumigation products; green tea instead of coffee; ensure the daily intake of fresh vegetables 300g, fruit 200g or more.