Diet is very important to human health, but “water can carry a boat, but it can also overturn the boat”, irrational diet can also cause cancer, “disease enters by the mouth” has been well known. Restriction of high-fat diet, more intake of vegetables and soy products containing fiber, vitamins, carotene, can help prevent digestive system cancer. All of these substances can be obtained from food. This indicates that a correct dietary structure, which ensures the supply of essential nutrients to the organism, has the potential to form an autonomously dynamic defense and reduce cancer-causing factors. A regular diet that conforms to the principles of a healthy diet can effectively reduce the risk of cancer. Healthy diet has the following aspects: 1. Diversification of food varieties Dietary taboos single diet don’t favoritism. Food intake can be varied from day to day, and fruit snacks change with it. Staple food noodles to whole wheat is the best, buckwheat, round-grained rice, glutinous rice, black rice, corn, bean noodles should also be alternated, three meals a day with changes. Seven days a week there is alternation. As the saying goes, “five grains of mixed food benefits Fukang.” Vegetables in the green vegetables, cauliflower, real fruit, root vegetables to a variety of choices, diversified food is conducive to the full range of nutrients needed to provide the human body, including micronutrients. 2, coarse and fine mix to be reasonable Recent nutritionists believe that: can not be decomposed by the body’s digestive enzymes of dietary fiber, very beneficial to human health. Dietary fiber refers to cellulose, hemicellulose, lignin, pectin and other substances. Foods included are: mixed grains, beans, vegetables, fruits, etc.. They can stimulate intestinal peristalsis in the body and reduce chronic constipation. The roughage of dietary structure is directly involved in the prevention of rectal cancer and colon cancer. Japonica rice, white noodles, buckwheat noodles, barley noodles alternately as staple food, red beans and rice, eight treasures congee, two rice (rice and millet), etc., all belong to the coarse and fine food, often eaten for health. 3, according to the principle of human meal preparation People have strong and weak, fat and thin, old and young, meal preparation should be based on the growth period of people, nutritional status, the implementation of different principles of crowd categories. For example, the basic metabolism of leukemia patients rises, the body’s need for various nutrients increases, a bedridden leukemia patients, a day’s calorie consumption is equal to the calories consumed by a manual laborer, calorie consumption makes glucose, fat metabolism rate to strengthen. According to this mechanism, the nutritional requirements of leukemia fever diet are high protein, high calorie, high vitamin diet and as long as it can be absorbed as much as possible to increase a variety of nutrients, meals can be 3 to 6 meals a day. 4, cooking food has to pay attention to reasonable cooking is to prevent the destruction and loss of nutrients, kill pathogenic microorganisms and parasitic eggs. Adopt various methods to preserve as many nutrients as possible, make food easy to digest and absorb, and avoid the production of carcinogens and other harmful substances. In order to ensure that the food harmless changes and good mouth requirements, try to shorten the heating time and control the appropriate temperature of rapid frying is conducive to the retention of a variety of vitamins; vegetables now eat now buy, wash the vegetables after washing cut; fish, meat with starch or egg white slurry paste, so that its nutrients to reduce the loss of fresh yeast flour, increase the B vitamins in the dough to promote the absorption of iron, calcium, zinc, magnesium, etc.; stir-fried vegetables appropriate Add vinegar, can save vitamin C.