The main physiological function of the colon is to absorb water and store food residues to form feces, and the glands of the colon mucosa can secrete thick mucus, which is alkaline and can neutralize the fermentation products of feces. When the colon is suffering from cancer, the physiological function is damaged, and the defecation function and the general condition are affected, such as diarrhea, difficulty in defecation, general wasting and other symptoms. If we do not pay attention to the diet and eat some indigestible food and cancer-promoting food, it will aggravate the progress of rectal cancer and make the whole body fail. Patients with rectal cancer must pay attention to their daily diet. Research proves that high-fat diet will promote the occurrence of intestinal tumors, especially polyunsaturated fatty acids, which can lower blood lipids but have a pro-cancer effect. Cholesterol itself is not carcinogenic, but reacts with gallstone acid at the same time and has a cancer-promoting effect, indicating that gallstone acid is a cancer-promoting factor. Therefore, patients with rectal cancer should not eat too much fat, with total fat accounting for less than 30% of total caloric energy, and the ratio of animal and vegetable oils should be appropriate. In other words, in a day’s meal, including the amount of fats in the food itself, plus the oil used in cooking, the daily fat should be less than 50 grams. Some friends are afraid of coronary heart disease, control animal fat is very strict, often to vegetable oil, or even do not eat animal oil, which will cause excessive peroxide in the body. Because the carbon chain in vegetable oil is unstable and easy to oxidize, if you eat some animal fat properly, it will make the carbon chain stable, not easy to oxidize, and reduce the formation of free radicals in the body, so we must eat scientifically, pay attention to the reasonable ratio of fats and oils, it is recommended that the ratio of saturated fatty acids to polyunsaturated fatty acids and monounsaturated fatty acids is 1:1:1. The diet should pay attention to eating more dietary fiber-rich vegetables, such as celery, leeks They can stimulate intestinal peristalsis, increase the number of bowel movements and take away carcinogenic and toxic substances from feces. If rectal cancer bulges into the intestinal cavity and the intestinal cavity becomes narrower, the intake of dietary fiber should be controlled because excessive intake of dietary fiber can cause intestinal obstruction. At this time, easy-to-digest, soft and semi-fluid food should be given, such as millet porridge, thick lotus root soup, rice soup, congee, cornmeal porridge, egg custard, tofu brain, etc. These foods can reduce the stimulation to the intestinal tract, pass through the intestinal cavity more smoothly and prevent the occurrence of intestinal obstruction. The diet of post-operative rectal cancer patients should be the same as that of other gastrointestinal surgery patients, and should be given according to medical advice. We should pay attention not to eat too much fat and oil, but to reasonably match sugar, fat, protein, minerals, vitamins and other foods, and to have cereals, lean meat, fish, eggs, milk, all kinds of vegetables and soy products every day, and not too much of each kind. This will replenish the various nutrients required by the body. If you cannot eat normally in the early stage after surgery, intravenous rehydration should be the main focus. Pay attention to strengthen care and diet nutrition after surgery to promote patients’ recovery. In the early stage of rectal cancer, there are often changes in stool, sometimes constipation, sometimes diarrhea, blood in stool, and some patients have alternating constipation and diarrhea. Therefore, patients with early-stage bowel cancer should pay attention to stool regulation and consume foods with more coarse fiber in the diet, such as potatoes, sweet potatoes, bananas, young leafy greens, etc., but the processing should be meticulous to avoid stimulation of tumor parts by excessively rough food. Foods rich in fiber can make the stool have a de facto volume, which can prevent constipation and prevent diarrhea to a certain extent, and can ensure regular daily bowel movement. Due to the malignant growth of tumor invading into the intestine, patients with advanced bowel cancer have different degrees of bowel obstruction and reduce the capacity of food. At this time, patients should be given nutritious food with less coarse fiber, such as eggs, lean meat, soybean products, fine grains, tender leafy vegetables, etc.; they should also drink more honey water and eat bananas and duck pears, among which honey has the best laxative effect.