To prevent tumor, start from the following points: 1. Diversify food, mainly choose plant foods, such as vegetables, fruits, beans, and use coarse grains. 2. Avoid being too light or too heavy. 3.Adhere to physical activity, brisk walking or similar exercise for one hour a day, and participate in more active exercise for at least one hour a week. 4.Check to eat 400-800g of various vegetables and fruits every day, keep 3-5 kinds of vegetables and 2-4 kinds of fruits. 5.Eat cereals, legumes, roots and tubers a variety of food 600-800g per day, eat more coarse processed cereals, limit the intake of refined grains. 6, encourage not to drink alcohol. If you drink alcohol, limit it to 2 cups for men and 1 cup for women. (One glass of wine is equivalent to 250ml of beer, 100ml of wine and 25ml of white wine). 7, control the intake of meat less than 80g per day, the best choice of fish, poultry instead of red meat (pork, beef, lamb). 8, limit the high fat content, especially the animal fat content of food. Choose vegetable oils, especially those with high monounsaturated fatty acid content and low hydrogenation. The energy intake of fats and oils accounts for 15-30% of total energy. 9, reduce the intake of pickled food and salt, salt less than 6g per day. 10, avoid food contaminated by fungal toxins and long-term preservation of food at low temperatures. 11, easy to spoil food should be refrigerated or other appropriate methods of preservation. 12, control food additives, pesticides and residues in food below the safe limit level, and the implementation of appropriate and effective supervision and management. 13, do not eat burnt food, avoid burning meat and fish. Try to eat less meat and fish smoked directly on the flame, as well as smoked and cured fish and meat. 14, generally do not need to take supplements. It is especially important to note that although smoking is not a dietary behavior, the dangers of smoking cannot be ignored in any cancer prevention.