Nutritionists have proposed the pyramid diet, which refers to the 7 types of nutrients such as protein, carbohydrate, fat, vitamin, inorganic salt, water, fiber, etc., which should be complete, sufficient in quantity, appropriate in proportion, and balanced in supply and demand, and can be described by an image of “pyramid” structure. Dietary principles and requirements for malignant tumor patients 1. Dietary guiding principles Malignant tumor patients should maintain stable weight and ideal weight during the treatment and recovery period, which is beneficial to their prognosis. Because there are many studies proving that patients who lose weight, or/and muscle mass, will have adverse clinical outcomes and hospitalization outcomes, including decreased quality of life, increased incidence of treatment toxicities, decreased treatment tolerance and compliance, shorter survival, longer hospitalization, and increased hospitalization costs. To maintain body weight and keep ideal weight, the main methods are proper diet and exercise. This standard mainly applies to the malignant tumor treatment period and early recovery period. Patients in this stage, due to the tumor itself and anti-tumor treatment, often lead to lower intake and weight loss, which induce or aggravate the occurrence of malnutrition. Therefore, it is recommended to give high energy diet. It is recommended to increase the proportion of fat in the diet and decrease the proportion of carbohydrate to adapt to the special metabolic characteristics of tumors. Increase the protein content in the diet and consume more high-quality protein to slow down the protein degradation and reduced protein synthesis caused by tumors. Sufficient intake of vegetables, fruits and other plant foods to ensure adequate intake of vitamins and minerals. Since tumor cells have a high capacity for glucose uptake and are metabolized mainly by glycolysis, it is recommended to limit the intake of sugar, especially refined sugar. When malignant tumor patients cannot meet the target intake even after dietary guidance during the treatment and recovery period, enteral and parenteral nutrition therapy is recommended. 2. Recommended energy and nutrient intake Energy: Studies have shown that the mean value of basal metabolic rate of tumor patients is approximately the same as the mean value of normal people. Then adjust to individualized energy standard according to patient’s activity level and stress condition. Protein: In patients with malignant tumors, excessive protein degradation and reduced protein synthesis can occur at an early stage, manifesting as the loss of Soul tissue group, which reduces the compliance and tolerance of anti-tumor therapy and shortens survival time. Therefore, it is recommended to have a high protein diet (fish, meat, eggs, etc.), generally 1-1.2g/kg/d, and 1.2-2g/kg/d for severe nutritional depletion. Fat and carbohydrate supply: Since the normal cells of tumor patients have normal or enhanced ability to oxidize fatty acid, while the tumor cells have significantly reduced ability to oxidize fatty acid, and the tumor cells have stronger ability to take up glucose than normal cells, and the normal cells have impaired glucose tolerance, it is recommended to increase the ratio of fat supply and reduce the ratio of carbohydrate supply, and the ratio of fat to sugar supply can reach 1:1. When the patient has high triglycerides or symptoms such as greasiness, nausea and diarrhea, the fat to energy ratio should be adjusted downward according to the clinical situation. When the patient is accompanied by diabetes mellitus, the dietary guidance for diabetes mellitus and the dietary guidance standard for malignant tumor patients should be referred to at the same time to keep the patient’s blood sugar normal and stable. Food of n-3 fatty acid source can be increased appropriately to reduce cancer-related chronic inflammatory response. Water and electrolytes: water quantity generally follows the supply according to physiological needs, given at 30-40 ml/ kg/d, so that the daily urine volume is maintained at 1000~2000 ml, and water intake is adjusted according to urine volume. When the diet is normal and rich and varied food is consumed, no additional electrolyte supplementation is needed. Elderly people, patients with heart, lung, kidney and other organ dysfunction pay special attention to prevent excessive fluid. Vitamins and micronutrients: Due to elevated markers of oxidative stress and decreased antioxidant levels in cancer patients, higher doses of antioxidant vitamins may be considered, but at the same time excessive antioxidants have the potential to reduce the effectiveness of some antitumor therapies, and there is insufficient research evidence on whether supplementation with antioxidant vitamins and micronutrients is clinically beneficial. Therefore, it is recommended that vitamin and micronutrient supply be supplemented according to the recommended daily allowance (RDA). If patients have a rich and varied diet and are able to meet the target requirements, no additional vitamin and micronutrient supplementation is needed. 3, food selection Cereals and potatoes Cereals include rice, noodles, mixed grains, and potatoes include potatoes, sweet potatoes, cassava, etc.. Mainly provide carbohydrates, protein, dietary fiber and B vitamins. Cereals are the main source of energy and should be more than half of the total. More and more scientific studies have shown that diets based on plant foods can avoid the defects of high energy, high fat and low dietary fiber dietary patterns and are beneficial to cancer prevention. It is advisable to eat 50g-100g of cereals per day, as the cereals are too finely processed and most of the vitamins, minerals and other nutrients and dietary fiber contained in the surface layer will be lost. Therefore, it is recommended that it is best to eat more than 50g of coarse grains every day. The combination of coarse and fine grains is conducive to the reasonable intake of nutrients. In the early postoperative stage of colorectal cancer, coarse grains intake is restricted in order to reduce the amount of stool. In addition, insulin resistance caused by tumor and the damage to the body caused by radiotherapy treatment lead to the occurrence of diabetes or impaired glucose tolerance in a considerable number of tumor patients. Coarse grains have lower glycemic index than finely processed carbohydrates, which is more conducive to blood sugar control. Animal food, including meat, poultry, fish, milk and eggs, is a good source of high quality protein, lipids, fat-soluble vitamins, B-group vitamins and minerals for human beings, and is an important part of a balanced diet, and is also the food that is advocated to be consumed more by patients with tumor. According to “Dietary Guidelines for Chinese Residents 2007”, the recommended daily intake is 50g~100g of fish and shrimp, 50g~75g of livestock and poultry meat, 25g~50g of eggs. milk is a kind of natural food with complete nutrients, suitable composition ratio, easy to digest and absorb, and high nutritional value, mainly providing high quality protein, vitamin A, vitamin B2 and calcium. However, the relationship between milk and dairy products and tumors is still controversial, therefore, no special recommendation is made for milk and dairy products for the time being. Beans and soy products Beans and soy products are an important source of high quality protein, dietary fiber, vitamins, minerals and phytonutrients (phytosterols) and are cholesterol free. When consumed together with cereals, beans can increase protein utilization by complementary protein effects. There are many types of soy products on the market today, which can be broadly divided into traditional soy products, soy milk-based soy products and new soy protein-based soy products. During the processing of soy products, cottonseed sugar and hydrosugar, which can cause abdominal distension, are removed, while the proteins and trace elements in soybeans are basically retained in soy products. At the same time, soy products are rich in essential fatty acids and phospholipids, and do not contain cholesterol, making them a good substitute for meat products. Soy saponins, soy isoflavones and soy peptides, which are mainly found in legumes, may have a positive effect on cancer prevention and treatment. Vegetables and fruits To prevent cancer and chronic diseases, the World Health Organization recommends eating at least five servings (at least 400 grams) of different types of non-starchy vegetables and fruits daily. In a review published by the World Cancer Research Fund, it was suggested that increasing the intake of vegetables and fruits could have a possible protective effect against tumors of the whistling and digestive systems. Results of foreign studies have shown mixed findings on the effects of vegetables and fruits on cancer prevention. Eating more vegetables and fruits can reduce the incidence of cancer in women; more intake of yellow-green vegetables and fruits can reduce the mortality rate of cancer; there are also reports that the intake of vegetables and fruits has no significant relationship with the risk of cancer. Vegetables and fruits are low in protein and fat and rich in vitamins C and E, dietary fiber and important phytochemicals. Vegetables and fruits contain many components that are considered to be cancer-preventive, such as vitamin C, which has antioxidant properties, beta-carotene and selenium. Epidemiological studies have shown that increasing dietary intake of vitamin C-rich vegetables and fruits can reduce the risk of stomach cancer as well as other cancers by mechanisms that may be related to free radical scavenging and blocking the formation of certain carcinogens. Cruciferous vegetables such as cabbage, broccoli, cauliflower, and kohlrabi contain several biologically active components that may have anticancer effects and can help maintain thyroxine activity and thus be beneficial to tumor patients. However, these vegetables should not be overcooked. Other carotenoids such as lutein and lycopene contained in dark colored vegetables and fruits also have antioxidant effects. The recommended intake of vegetables and fruits should be as fresh as possible. Fruit juices contain a lot of sugar but lack dietary fiber, so they are generally not recommended. The percentage of juice in a beverage is indicated on the package label, such as “25% juice” or “100% juice”. Some labels say they provide 100% nutrition, such as “provides 100% of the recommended daily allowance of vitamin C”. However, unless the package says “100% juice”, it is generally not 100% juice. These juice drinks contain very little juice and are sugary drinks rather than real juice. Although 100% fruit juice is part of a healthy diet, it lacks dietary fiber. Consuming too much juice can increase caloric intake. Fats and oils: A variety of rich sources of fats and oils, including n-6 polyunsaturated fatty acids, n-3 polyunsaturated fatty acids, and monounsaturated fatty acids, are beneficial in maintaining inflammatory balance and reducing lipid peroxidation in oncology patients, so it is recommended that a variety of vegetable oils be used alternately. Studies have shown that supplementation with 2-3g of n-3 fatty acids from fish oil sources per day can help stabilize weight loss in tumor patients with cachexia. Nuts: Nuts are an important source of n-3 fatty acids, and they are also rich in vitamin E and fiber. Therefore, moderate consumption of nuts is recommended.