Sugars, or carbohydrates, are the body’s main source of energy, and tumor patients are no exception. Adequate daily intake of carbohydrates can reduce the body’s protein consumption, improve the patient’s nutritional status and ensure the therapeutic effect. Tumor cells’ main source of energy is also sugar, some people worry that eating carbohydrates will promote the rapid growth of tumor cells, so they suggest starvation therapy to curb the growth of tumor cells, but various studies have shown that starvation therapy can not starve the tumor cells, but rather reduces the body’s nutritional status and accelerates the deterioration of the disease. How to ensure the nutritional supply of patients while limiting the growth of tumor cells? The general principle of diet is to appropriately reduce the proportion of carbohydrate energy supply and increase the proportion of fat energy supply. Specifically, the choice of sugar is delicate. Which kind of carbohydrates should tumor patients choose? Foods rich in complex carbohydrates, such as cereals, beans, potatoes, etc., should be chosen, and foods rich in monosaccharides, such as white sugar, icing sugar, candied fruit, preserved fruit, sweet drinks, honey, and snacks with high sugar content, should be avoided. Cook in a way that minimizes the use of sugar, honey, etc. Patients with chronic gastrointestinal diseases need to limit foods high in monosaccharides, which affect intestinal flora and can easily induce gastrointestinal tumors. Gastrointestinal tumor patients also need to limit salt, soy sauce, pickles, etc., do not eat spicy and stimulating condiments, such as anise, fennel, pepper, peppercorns, raw onions, ginger and garlic. How to control the amount of carbohydrates for tumor patients? It accounts for about 40% of the total energy. If your doctor recommends you to have a total energy of 1600 kcal a day, then the sugar supply is about 640 kcal, which is about 160 grams of raw rice and noodles, about 320 grams of ripe rice, and 210-240 grams of steamed buns. If you consume too many carbohydrates, especially refined sugar, you can create a high-sugar environment in the body, which not only promotes the rapid growth of tumor cells, but also may cause lipid metabolism problems and aggravate the disease. Dietary fiber is also a carbohydrate, a polysaccharide that cannot be digested and absorbed by the human body, and has a good anti-cancer effect. It can adsorb and dilute carcinogenic substances, especially preventing colon cancer has a great role. It is suggested that tumor patients should eat more vegetables, coarse grains, fruits, etc. Fruits need to be limited, about 250 grams a day. There are some polysaccharides with health effects, such as mushroom polysaccharides, ganoderma lucidum polysaccharides, fungus polysaccharides, etc., which can stimulate the immune system and improve immunity, and patients with tumors can eat mushrooms, fungus, wolfberry, sea cucumber, ganoderma lucidum, etc. as appropriate.