High-fat and low dietary fiber diets are important risk factors for the high incidence of colorectal cancer. A high-fat diet, for example, is also known as a “catalyst” for colorectal cancer. Americans prefer fried foods, dark red meats (beef, lamb, chicken), and smoked foods. These high-fat foods contain large amounts of saturated fatty acids, which can easily lead to disruption of the composition of the colonic flora and promote the generation and development of carcinogens. In contrast, the incidence of colorectal cancer in Asian countries such as China and Japan is significantly lower than that in the United States, mainly because of the low intake of high fat. Therefore, limiting fat intake to less than 30% of total calories is the main means to prevent colorectal cancer. In addition, the prevention of colorectal cancer should pay attention to other risk factors. For example, people who have had appendicitis surgery, history of colon adenoma and family history of bowel cancer should pay attention to stool condition and have colonoscopy once a year. Changes in stool habits, such as increased frequency of stool and constipation, are early symptoms of colon cancer. If there are symptoms such as blood in stool, anemia, weight loss, weakness and low fever, it means that the disease has developed to the middle and late stage, and colonoscopy and barium enema should be performed as soon as possible to clarify the diagnosis. Dietary fiber is called “no nutrition” by nutritionists, because its role is irreplaceable by other nutrients. Lack of dietary fiber prolongs the residence time of feces in the intestine, causing the intestine to reabsorb waste and causing carcinogens in the feces to irritate the intestinal wall for a long time. Therefore, fiber is known as the cleanser of the intestine, which acts like a small brush to promote intestinal peristalsis, cleanse the intestinal tract of garbage and waste, and reduce the residence time of intestinal carcinogens, thus reducing the risk of colorectal cancer. The American Cancer Society recommends 30 to 40 grams of dietary fiber per person per day; the standard daily intake for Japanese under 70 years old is 19 to 27 grams; the recommended standard in China is 30 grams of dietary fiber per day. So, how many grams of fresh fruits and vegetables contain 30 grams of dietary fiber? Generally speaking, it is approximately equivalent to 10 apples, 19 bananas, 4 pounds of celery, 6 tomatoes, etc. Obviously, it is difficult for the average person to achieve such an intake. However, eating more fiber-rich foods, even if they do not reach the standard amount, will play an important role in colorectal cancer prevention. In addition, corn, millet, barley, wheat bark (rice bran) and wheat flour (material of black bread) and other miscellaneous foods have more fiber content; carrots, string beans, peas and potatoes among vegetables are also high-energy foods with fiber. Sweet potatoes are known as the champion dish of anti-cancer food for this very reason. Therefore, it is important to consume more potatoes, fish and soy products, especially grains and cereals, such as wheat and bran-protected flour and other foods with high fiber, all of which are beneficial to the prevention of intestinal cancer.