The main physiological function of the colon is to absorb water and store food residues to form feces. The glands of the colonic mucosa secrete thick mucus, which is alkaline and can neutralize fermentation products of feces. When the colon is suffering from tumor, the physiological function will be damaged and the defecation function as well as the general condition will be affected, such as diarrhea, difficulty in defecation, 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 colon cancer. Therefore, colon cancer patients must pay attention to their daily diet. Before 1970, there was no such word as dietary fiber in nutrition, and only the concept of coarse fiber was considered useless without any nutritional effect. Dietary fiber food can prevent many common diseases such as intestinal cancer, hyperlipidemia, heart disease, constipation, obesity and diabetes, etc. Only after this, dietary fiber caused experts to pay attention to and start research, crude fiber also renamed as dietary fiber, and become an important nutrient to maintain human health. The reason why it is believed that dietary fiber can effectively prevent colorectal cancer is that dietary fiber has strong water absorption, which can increase the volume of stool and make it form and facilitate its discharge, thus shortening the residence time of stool in the intestinal tract, reducing the contact between carcinogens and intestinal wall, lowering the concentration of carcinogens in the intestinal tract, and thus reducing the risk of colon cancer.