As the saying goes, disease enters by the mouth. The relationship between food and cancer has attracted great attention. According to statistics, more than 1/3 of cancers in the world population are caused by nutritional factors. Diet-related cancers mainly include esophageal cancer, stomach cancer, liver cancer, lung cancer, laryngeal cancer, breast cancer, pancreatic cancer and prostate cancer. Many people have misconceptions about diet, thinking that “high-grade and exquisite food must be rich in nutrients” and “as long as we eat more fish, shrimp, beans, fruits and vegetables, it must be a scientific diet to prevent cancer”, etc. In fact, the nutritional value of one or a certain type of food is very high. In fact, the nutrient composition of one kind of food or a certain kind of food, it is impossible to fully meet all the needs of the human body on nutrition, any monotonous dietary pattern or partiality habit will cause some nutrients in excess, and the lack of some other nutrients, resulting in nutritional imbalance, and one of the consequences of this imbalance is the inducement of cancer. Therefore, for most people, the prerequisite for cancer prevention lies in establishing a correct concept of balanced diet and guiding their daily diet. The occurrence of cancer can be roughly divided into three stages: The first is the initiation stage, in which DNA, the genetic material of normal cells, is damaged and the genetic factors of cancer are “awakened”. The second is the promotion stage, in which cell division is accelerated and the cancerous process is initiated. The third is the evolutionary stage, in which the tumor deteriorates and even metastasizes. The role of diet is mainly in the second and third stages. If the various food components in the diet are properly matched, the process of cancer can be stopped and slowed down, and vice versa, the formation of cancer will be promoted. It is undoubtedly necessary and useful to clarify the role of nutritional factors in the long and complex process of human cancer development. The following cancer-diet-related relationships are now relatively well established. The occurrence of esophageal cancer is related to the following: 1. Lack of vitamin A, vitamin C and vitamin E. 2. Lack of certain trace elements, such as molybdenum, zinc, magnesium and selenium. 3.Eating pickled and moldy food. 4, eating too hot and too rough food. 5, The incidence of esophageal cancer will increase significantly if you drink alcohol and smoke. The occurrence of liver cancer is related to the following points: 1. aflatoxin contamination of food. 2. 2. Pollution of water source. 3. Japanese scholars have found that frequent late-night snacks are easy to cause stomach cancer. 4. Alcoholism: alcoholism obviously damages the liver. The occurrence of colon and rectal cancer is related to the following points: 1. High-fat diet. Insufficient dietary fiber. 3.Other factors: eating more food rich in vitamin A can reduce the occurrence of colorectal cancer. People who drink more beer or both beer and other alcohol have higher incidence of colorectal cancer. In addition, high-fat and high-calorie diets are positively related to breast cancer; lung cancer patients are often deficient in vitamin A and selenium; ovarian cancer is related to low calcium; high-fat diets may be related to the occurrence of endometrial, ovarian, prostate and gallbladder cancers; smoking not only leads to lung cancer, but also has a clear relationship with oral cancer, hypopharyngeal cancer, esophageal cancer, gastric cancer and cardiovascular disease; thyroid cancer is related to dietary iodine deficiency; lack of zinc and selenium is related to a variety of cancers; and the incidence of zinc and selenium is associated with a variety of cancers. selenium is positively correlated with the occurrence of a variety of cancers. How to prevent cancer entrance, in fact, is a study, we can follow the following guidelines: 1, food to plant food as the center, a variety of intake. 2, maintain a proper weight, BMI (body mass index) maintained at 18, 5 to 25. BMI is the weight loss index, 22 most standard, that is, the weight divided by the square of height, for example, weight of 72 kilograms, height of 1, 73 meters, then the BMI is 24. 3, often moderate exercise. Exercise can maintain physical strength, maintain the body’s original resistance. 4, eat more vegetables and fruits. Yellow-green vegetables and fruits contain a lot of vitamin C, A, E and beta-carotene, which can prevent cancer. 5, cereals, beans, root vegetables. Take at least 600 to 800 grams a day. 6, it is best not to drink alcohol, 50ml per day limit. 7, sheep, pork. Consume less than 80 grams per day, and eat more fish and chicken. 8, control the amount of animal fat intake, moderate intake of vegetable fat. Too much animal fat intake is easy to fat. 9, salt adults 6 grams per day or less, seasoning to spice-based. Salt is the culprit of stomach cancer, try to eat less. 10, eat more fresh food, less canned food. Long-term preservation of food easy to germs. 11, food should be frozen, refrigerated storage. However, the refrigerator can not be regarded as a universal box, food can not be hidden for too long. 12, avoid processing products or additives. 13, do not eat burnt food. 14, eat less nutrients, supplements. 15. Quit smoking. Dietary prevention of cancer mainly emphasizes balance, not the intake of individual nutrients. The state recommends the “Balanced Dietary Pagoda for Chinese Residents” to guide the diet of Chinese residents. The “Balanced Diet Pagoda” is a nutritionally ideal dietary pattern. The general principle is that there should be adequate nutrition in the diet, and that food should be diversified, with plant-based food accounting for more than two thirds of the total, including vegetables, fruits, beans and roughly processed staple foods.