One person in the United States is diagnosed with cancer every 23 seconds, and one-third of women and one-half of men in the United States are at risk of developing a tumor in their lifetime. Despite being the second leading disease in the United States after cardiovascular disease, tumors are the number one cause of death in the United States. There are currently 10.5 million cancer patients in the United States, equivalent to 4% of the total U.S. population, and 1.5 million deaths per year. The annual cost of tumor treatment in the United States is$210 billion, which translates to as much as RMB 1,323 billion at a rate of 6.3, equivalent to the entire gross national product of Beijing in 2010, the latter being RMB 1,377.8 billion. It is found that tumor is a metabolism-related and lifestyle-related disease, one third of tumors are related to daily diet and nutrition, and digestive tract tumors are more closely related to diet. Through proper nutrition and adjusting dietary habits can prevent 30-40% of tumors. The new concept of malnutrition includes two aspects of under-nutrition and over-nutrition. The relationship between malnutrition and tumor includes two meanings: Firstly, malnourished people are more prone to tumor, simply put, people who are excessively thin (under-nutrition) and excessively obese (over-nutrition) are prone to tumor, the mechanism of which involves immune imbalance, metabolic disorders and other aspects; secondly, tumor patients are more prone to tumor. Malnutrition, caused by tumor, is manifested as nutritional deficiency, i.e. wasting and weight loss. The mechanism lies in the influence of tumor itself and the interference of anti-tumor treatment! Data show that up to 50% of tumor patients have malnutrition at the time of initial diagnosis. Compared with benign diseases, malnutrition in malignant tumor patients is more prevalent, more serious in impact, more complex in mechanism and more difficult in treatment. Malnourished tumor patients have shorter survival period, malnourished tumor patients cannot tolerate radiotherapy, chemotherapy and surgery, malnourished tumor patients have more complications or toxic side effects of treatment, and malnourished tumor patients are not sensitive to treatment response! Therefore, tumor patients need nutritional support even more! Nutritional support should become a specialized treatment tool independent of surgery, chemotherapy, radiation therapy, biological therapy, supportive therapy, palliative therapy, etc. It should become a core part of multidisciplinary comprehensive treatment for tumor patients, and should become the most basic and necessary treatment measure for tumor patients! The nutrition of tumor patients includes two parts: daily diet at home and professional nutrition treatment in hospital. Tumor patients should improve their nutritional status from the following aspects: 1. Maintain healthy weight Maintaining healthy weight is both an effective primary prevention (i.e., reducing tumor occurrence) and tertiary prevention (prolonging life of tumor patients) measure. Overweight or obesity is a risk factor for the development of breast cancer, colorectal cancer, endometrial cancer, pancreatic cancer, kidney cancer, multiple myeloma, non-Hodgkin’s lymphoma, cervical cancer, bladder cancer, liver cancer, thyroid cancer, ovarian cancer, pancreatic cancer, esophageal cancer, prostate cancer, etc. The incidence of tumors in overweight and obese people is significantly higher than that in people with normal weight. Overweight or obesity at the time of tumor diagnosis and after treatment is associated with poor prognosis of tumors, that is, the prognosis of overweight and obese tumor patients is worse than that of normal weight tumor patients, because it is more difficult to control tumor in overweight and obese patients, and the risk of second tumor increases, and coexisting diseases such as cardiovascular disease and diabetes increases. On the other hand, weight loss is also a negative factor, and progressive weight loss or non-subjective efforts (e.g. dieting, weight loss, exercise) are important indicators of tumor recurrence, metastasis, and progression. Tumor patients have poorer prognosis. 2.Reduce calorie intake It is good to eat seven or eight minutes full for each meal. As the saying goes, “Eat one or two bites less at each meal and live easily to 99”. Epidemiological survey found that limiting calorie intake can make people live longer, prevent tumors for healthy people, and prolong survival for tumor patients. Restricting calorie intake can affect the organism from various mechanisms such as reducing oxidative damage, increasing apoptosis and affecting metabolic enzyme functions, resulting in lower blood glucose and lower insulin levels, as well as enhancing self-eating ability and certain DNA repair processes, thus preventing and controlling metabolism-related diseases such as obesity, hypertension, hyperlipidemia, fatty liver and diabetes, which are inextricably linked to the development of tumors. These metabolic diseases are inextricably linked to the development of tumors. Therefore, it is important to “keep your mouth shut” for your health. The purpose of reducing calorie intake is to prevent excessive nutrition, which should be based on the premise of maintaining normal nutrition and normal weight of the body; reducing calorie intake is not starvation; starvation will only lead to malnutrition and shorten the survival time of tumor patients, and tumor will not be starved to death. 3, reduce red meat intake We often eat various kinds of meat according to the red and white color of raw meat (before cooking) divided into red meat and white meat, except salmon, which is white meat despite its deep red color. Studies have found that red meat can increase the incidence of many types of tumors, while white meat has no such effect. In daily life, it can be simply classified roughly as follows: four-legged animals such as pigs, horses, cows and sheep are red meat, two-legged animals such as chickens, ducks, geese and birds are red and white, and animals without legs such as fish are white meat; four-legged is better than two-legged, two-legged is better than no-legged; domesticated is better than wild; captive is better than free-range; land is better than water, river is better than sea. Processed meat products such as sausage, cured meat, ham, etc. are collectively called processed meat. Processed meat has similar effects to red meat and can increase the incidence of many kinds of tumors. Therefore, we need to eat less red meat and processed meat. Animal meat contains high quality protein, which is better than plant protein, we can’t not eat meat; it is recommended to eat white meat instead, which is recommended 2-4 times a week, 50-100g (1-2 taels) each time. 4, reduce fat intake Fat is commonly known as oil. According to whether fatty acids contain unsaturated double bond, divided into saturated fatty acids such as pork, poultry, milk, butter, cheese, coconut, palm, fatty acids in palm kernel and unsaturated fatty acids such as peanut oil, seafood oil, unsaturated fatty acids are divided into monounsaturated fatty acids such as olive oil, peanut oil, vegetable oil and polyunsaturated fatty acids such as corn oil, safflower oil, sunflower oil, flaxseed oil, polyunsaturated fatty acids They are also divided into n-3 fatty acids such as fish oil and n-6 fatty acids such as soybean oil. Studies have found that aquatic animal oils such as fish oil are better than terrestrial animal oils such as lard; vegetable oils are better than animal oils, tree oils are better than shrub oils, and perennial plant oils such as tea oil are better than annual plant oils such as sesame oil. Studies have reported that fat at <20% of dietary energy can reduce the risk of breast cancer recurrence by 24%, and the effect is even more dramatic in estrogen receptor-negative breast cancer. High intake of saturated fatty acids shortens disease-free survival in prostate cancer, and monounsaturated fatty acids prolong survival. Current recommendations: fat should account for <20-35% of dietary energy, saturated fatty acids <10%, and trans fatty acids <3%. N-3 fatty acids can benefit tumor patients by improving cachexia, improving quality of life, and enhancing the efficacy of radiotherapy and chemotherapy. Foods rich in N-3 fatty acids such as fish and pecans can reduce the risk and incidence of cardiovascular disease, thus reducing the overall risk of death in tumor patients. Fruits and vegetables are rich in vitamins, minerals and antioxidants, which have good preventive effects on tumors for normal people and can reduce coexisting diseases such as cardiovascular diseases for tumor patients, thus prolonging tumor survival time. The American Cancer Society recommends 5 servings of fruits and vegetables per day, at 90kcal/serving, each serving of vegetables is equivalent to 100g of vegetables, each serving of fruit is equivalent to one natural unit of measurement of fruit such as an apple, a banana, an orange, a pear, a mango. Half a cup of 100% fruit juice is equivalent to one serving of fruit, half a cup of 100% vegetable juice is equivalent to one serving of vegetables. Cruciferous vegetables, ginger, green tea, strawberries, etc. all have good anti-tumor biochemical properties. Cruciferous vegetables include cabbage: chard, cabbage heart, cabbage, purple cabbage shoots, red cabbage shoots, etc.; kale: cauliflower, cauliflower, kale, broccoli, bulb kale, etc.; mustard: leaf mustard, stem mustard (head cabbage), root mustard (big head cabbage), squash, etc.; radish; aquatic vegetables. Dark green and yellow fruits and vegetables are the richest in phytochemicals. 6, increase grain intake whole grains including (large, small, black, oats) wheat, (large, yellow) rice, corn, sorghum, millet, etc. They are rich in fiber, micronutrients. They are rich in fiber, micronutrients and phytochemicals such as polyphenols, terpenes (lignans), lignans, etc. Phytochemicals have shown good anti-tumorigenic effects in laboratory studies, and they either prevent the occurrence of tumors alone or are more likely to act in combination. As the micronutrients of whole grains will be seriously damaged during processing, such as vitamin E in coarse grains will be reduced by 92% in the finishing process, so grains should not be refined, and advocate that food is not coarse, food is not miscellaneous. 7, pay attention to food safety Preventing food bacterial contamination is the first food safety requirement for tumor patients. It is especially important during the medical immunosuppression caused by radiotherapy and chemotherapy. Patients and food processors, including family members, must follow food safety guidelines to reduce the risk of food-borne illness. These food safety guidelines include careful hand washing before eating and food preparation, careful washing of all items, separation of raw food from cooked food, thorough washing of any items that have come in contact with raw meat such as fish, poultry and eggs, cooking food at a reasonable temperature, and keeping food at a low temperature (<4 C). Special care should be taken to prevent bacterial contamination when eating in restaurants and to ensure the cleanliness of drinking water at home, using filters is recommended. Microwave oven and gas steam are recommended for food processing. Boiling, grilling, frying and stir-frying are not recommended because boiling will destroy a lot of water-soluble nutrients, and high temperature grilling, frying and stir-frying will produce a lot of harmful or carcinogenic chemicals such as benzo(a)pyrene. 8.Professional nutritional therapy When tumor patients cannot maintain normal nutritional requirements and healthy weight due to any reason, they must receive professional nutritional support, including oral nutritional supplementation and parenteral nutritional support. Oral nutritional supplementation is the partial replacement of daily food with high energy density food or enteral nutritional preparation, or as a supplement to inadequate daily diet to supplement the gap between daily dietary intake and the target requirement. Smaller and more frequent meals and reduced fluids are recommended. High energy density foods include peanut butter, dried fruits, cheese, yogurt, eggs, cereals, beans and avocados. If the body's needs are still not met by daily intake and oral nutritional supplements, parenteral nutrition support is recommended to supplement the daily diet and enteral nutrition with parenteral nutrition. Partial parenteral nutrition is of great significance to patients with advanced tumors who have severe toxic side effects during radiotherapy and chemotherapy and cannot eat normally.