There are two types of malignant tumors, one is called cancer and the other is called sarcoma. Any epithelial tissue that becomes malignant during embryonic development is called cancer. Not only skin, but also epithelial tissues including gastrointestinal, urinary and reproductive tissues, which are all connected to the outside, and digestive tract are all epithelial tissues. Stomach cancer, lung cancer, bladder cancer, etc. There is another type of cancer that is part-time from connective tissue, which is called sarcoma. For example, lymphosarcoma, osteosarcoma and so on, so once you look at the name of this diagnosis, you can know what is going on, so this is the essence of this cancer. Now I will tell you more about the incidence of cancer in Beijing, the incidence of cancer in 1996 is 5.2 times more than that in 1955. We have surveyed the hospitals and residents in urban areas, the incidence of colorectal cancer in the 1960s was less than 10 per 100,000; in the 1980s, it was 20 per 100,000; in the 1990s, it was 24 per 100,000; in 2001, it was 60.45 per 100,000; life has become better, people don’t worry about food and clothing, but basically, there are more and more cancer patients in the city. Why? It has something to do with diet, and bowel cancer is directly related to diet. The life is better, more meat is eaten, but not coarse food. There is less fiber and less vegetables to eat. Why do you get tumors? If we want to prevent tumors, we need to know why? Why do we get tumors is a question that has not been completely solved yet, why it suddenly grows in a disorderly manner? This is not very clear yet. But now there are some more recognized views, which I will introduce to you. In terms of the occurrence of tumor, there are two factors, one is endogenous and the other is environmental. Endogenous factors are mainly genetic factors, while external environmental factors include physical, chemical, viral and dietary factors. I am mainly talking about diet. Look at a statistic, we can see that out of 100 smokers, 25% get cancer. And then 35% of the diet. So as long as a reasonable and balanced diet can prevent 35% of tumors, if you don’t smoke, there will be one less tumor in four. Other factors such as alcohol consumption, food additives and occupational exposure are also important. But I mainly hope that we can know that a balanced diet, a balanced diet, a reasonable and healthy diet can prevent cancer, and not smoking can prevent cancer, so that almost half of the cancer can be prevented. What are the cancer-causing factors in food? Natural carcinogens in food, the so-called natural carcinogens are not artificially contaminated, is the food under some conditions it produces natural carcinogens. The first to say is aflatoxin, aflatoxin is one of the most toxic things in the world. Potassium cyanide, we may all know that potassium cyanide is very toxic, the acute toxicity of aflatoxin is ten times that of potassium cyanide. Aflatoxin can cause acute symptoms similar to infectious hepatitis, pathological and anatomical symptoms, clinical symptoms are very similar to hepatitis. Our country has reported acute toxicity of aflatoxin poisoning in Southern Africa India, that chronic long-term exposure can cause chronic hepatitis. If small doses of long-term exposure can induce liver cancer. We have done a lot of research, the general standard of toxicity are how many milligrams per kilogram, but the national standard for aflatoxin, that is, according to our laboratory, we did the experiment with rats, took the south to do the corn, the results of the state set the standard. Because it is mainly contaminated food is peanut corn rice, peanut oil, if the cow’s feed has aflatoxin, its milk can be discharged aflatoxin M, so are set very strict standards. Babies are not allowed to have any detectable aflatoxin in the milk products, the general oil in the peanut, rice are by ppb, how many parts per billion, is not more than 10 or 20 per kilogram, different food. Is a very strict standard, long mold needs temperature, humidity, so the south is humid, hot easy to mold, the northern beans or something better. But soy sauce should also be tested in the head, peanut oil should be tested. Where the peanuts have broken, it is best not to eat, do not throw away. Because you can not test, but these peanut oil manufacturers sell these food places should be tested for aflatoxin, detection is not complicated, is not difficult. This national standard, should be done in accordance with national standards, this is one category. There is another category is nitroso compounds, we have heard of this term? Nitrosamines have heard of, this is also known as natural carcinogens, it is how it came about? What foods are more? It is synthesized in the human stomach, under acidic conditions it can be synthesized. It will become nitrite after reduction with nitrate, and then decarboxylate with the amino acids of protein decomposition, into amines. The combination of these two is nitrosamines. There are many kinds of nitroso compounds, because the structure of the amine is different, the chemical structure is different, it has many kinds. There are some dishes with nitrates, so in this case, if it is not fresh, it is reduced to nitrite. Provided nitrite, and then eat the protein of the food is not fresh, there are amines. What might be in that commodity? Like enemas, meat sausages, ham meat, cooked meat products, why is it so red? Why do they look so good? Why is it grayish-red when you make it at home? Why is it so red? The sausage is very nice, the ham is very red, where does the red come from? What is it? It’s not the coloring, it’s the nitrates. After the nitrate is combined with hemoglobin, it is not afraid of heating, not destroyed, so the heating is still red color. Then why is it possible to synthesize nitrosamines? Because there is protein in the meat, there are amines. Why is it still allowed? To prevent botulism, nitrite can inhibit the growth of Clostridium botulinum, so it is allowed to use. But must be done in accordance with national standards, it will not be harmful to people. If arbitrarily added, arbitrarily put, in addition to the meat is not fresh, so it is easy to have nitrosamines. Also, the mouth must be kept clean. This will not synthesize nitrosamines in the stomach. There is also alcohol, alcohol can promote the growth of many tumors. From the mouth, throat, esophagus and other places to develop, we have long reported in China, drinking white dry can cause esophageal cancer, can cause stomach cancer. So if you want to drink alcohol, don’t drink too much. Finally, I have a preventive measure, the maximum number of alcoholic beverages a person can drink a day? In addition, alcoholic beverages, there are some harmful substances, such as asbestos, it may have asbestos when filtering, and so on, that is also cancer-inducing. Contaminants in food, this is more. Polycyclic aromatic hydrocarbons, pesticides, food packaging materials, vinyl chloride, benzene, etc., are all pollutants. These are all carcinogenic to people, there is no doubt. Food additives, food additives, one is saccharin, saccharin is not beneficial to animals. Saccharin is sweet when eaten, then there is no metabolism, eliminated by the urine in its original form, so it has side effects on the bladder. Animal experiments have shown that it can trigger and induce bladder cancer, but the effect on humans is not too certain. Investigation of workers in saccharin factories, manufacturing saccharin, but he did not have a particularly high incidence of bladder cancer, so we can use the Chinese regulations, but the dosage must be in accordance with national standards. There are also some colors, red-colored artificial colors, some of which can cause tumors. So there are some additives that can cause tumors, food cooking and processing, protein heating above 250 degrees, it will produce cancer-inducing substances. So the direct fire baked, burnt part can cause tumors. This has done a lot of experiments, basically the understanding is unified. The greasy things, repeatedly fried, on that one pot of oil, sold every day, the bottom of the pot of the substance, there are carcinogens. More than 350 degrees, then there are carcinogenic substances. Deep-fried, salted, now suspected of stomach cancer and salt-cured foods are related. Salt-cured food is one of the factors that induce cancer, smoked bacon, Iceland once did a survey, because of the climate in their place, the meat cut into a line, hanging in the kitchen, let it smoke, and then slowly eat. That place stomach cancer incidence is particularly high, the United States stomach cancer has declined, the results of the study that the refrigerator to preserve the results. Do not use these salt curing smoked baking these methods to store food, so these cooking methods are very important. So I hope that if you can agree with me, I hope you can spread the word. Tell your classmates, don’t eat lamb skewers, don’t buy them for a dollar a skewer, they pollute the environment. It’s not good for the individual, and it’s not good for the person who smokes the lamb skewers. There is a survey in Beijing, that is, housewives were using honeycomb coal at that time, and there was a high incidence of lung cancer among housewives, and later it was thought that the burning coal had carcinogenic substances. The nutrients in the protective factors food, vitamin ACE, why? It is some antioxidants, which include precursors of vitamin A, which can become vitamin A. These have antioxidant power. These have antioxidant capacity, it can target free radicals, it can quench free radicals. Because free radicals are very active, they can damage the cells, they can damage the DNA of the cells, and after that, they can become cancerous. For example, vitamin C and vitamin E can block the synthesis of nitrosamines and prevent the formation of tumors. This vitamin A has a protective effect on epithelial tissues, it can reverse what has already changed, it can reverse. But vitamin A can be toxic, we have reported in China, children go to the doctor, and then the doctor said, vitamin AC, AD is not enough, eat cod liver oil it. As a result, they ate until they were teenagers and did not know to ask the doctor again, which resulted in poisoning. Joints are fixed, disabled, this has such reports. The existing vitamin A, chemically called retinol, is now made into retinoic acid. Now chemical prevention has been carried out, and many topics are being done in the world. The use of this retinoic acid does not cause poisoning and then prevent the development of tumors. Therefore, vitamins are very important and must be taken in sufficient amounts, but not too much to cause poisoning. In addition to vitamins, the trace element selenium, which has an anti-cancer effect, selenium, which is also a strong antioxidant. Zinc has more than 200 kinds of enzymes that participate in human metabolism, so if zinc is lacking, the metabolism will be abnormal. In addition, the zinc content in the hair of esophageal cancer patients tested in Hong Kong is low, so zinc is considered to have an anti-cancer effect. Iron is also involved in many redox processes. The protective factor against cancer is also cellulose, which is not digestible and not available to people. Because people lack an enzyme, primates lack this enzyme, so monkeys also need to eat fresh fruits and vegetables. But ruminants, cattle, sheep just eat grass on the line, it does not need to eat fresh grass, hay can also be. It has an enzyme, it can digest this cellulose, using this into something nutritious. Why is cellulose able to prevent cancer? Because it is in the intestinal tract, it increases the volume of the intestine, it can not be digested, so that the timely peristalsis, timely movement of the intestine, does not cause the accumulation of stool. If the stool is dense, the toxins are in contact with the intestine for a long time and are easily damaged, which then causes rectal and colon cancer, so although cellulose is not digestible, it is needed for the physiological activities of the intestine. There are other phytochemicals, and now this is the most fashionable, lycopene, mushroom polysaccharide, ganoderic acid, and many, many more, and indeed many of them were not valued in the past. For example, lycopene was not taken seriously in the past, because it was known for a long time, but it was not taken seriously because it could not be turned into vitamin A. Now it is only discovered that it has physiological activity and it can prevent cancer. Similarly, flavonoids and so on, there are a large number of active substances in plants that have anti-cancer effects. There are many protective factors in garlic, in vegetables, fruits, onions and onions. Low-fat diet can also prevent cancer, high-fat food will make the bile secrete bile acid, so it will stimulate the lower gastrointestinal tract, so the high-fat diet can cause obesity. Obesity can cause many diseases, such as diabetes, hypertension, coronary arteriosclerosis, heart disease, stroke, etc. It also causes several tumors. Obesity can cause colon cancer, rectal cancer, breast cancer, ovarian cancer and so on, so eat a low-fat diet. Also establish good eating habits, do not eat especially hard, especially hot food, in addition to eat, chew slowly. Chewing slowly can be absorbed well, in addition to let the food fully with the saliva enzymes, so that it is fully mixed. In addition, chew slowly people generally do not over-eat, wolf swallowing, he ate a particularly large amount. So good eating habits, but also to reduce obesity.