A, smoked food smoked food contains a large number of polycyclic aromatic hydrocarbons and other heterocyclic compounds, carcinogenicity, the higher the temperature, the more the content is also. Second, fried food 1, the fat content is too high, easy to cause obesity; 2, easy to form polycyclic aromatic hydrocarbons and other heterocyclic compounds, the higher the temperature, the more content, carcinogenicity; 3, vitamins and other nutrients are destroyed (if you make the pot on fire, more undesirable). 4, repeated heating of fat can form fatty acid polymers and trans fatty acids, not only no nutrition, but also carcinogenic potential; PAHs: this category has more than 200 kinds, to 3, 4 benzo(a)pyrene carcinogenic effect is the strongest, from direct contact with open fire smoked food (such as electric oven smoked meat containing 23 micrograms / kg, open fire smoked meat containing 107 micrograms / kg) and incomplete combustion of coal carbon and wood directly produced. The content of carcinogenic 3,4 benzo(a)pyrene increases 10-20 times after the food is burnt, and the highest content is found in smoked, baked and fried foods (such as charred head, rice potpourri, charred yams, especially grilled lamb skewers, smoked sausages, smoked dried bean curd and bacon). Third, the pickled food vegetables contain more nitrate, in the pickling process, nitrate can be reduced to nitrite by bacteria (there are 1 million species of bacteria with this ability). The latter can form nitrosamines with the amines in food. Fourth, canned foods The solder at the bottom of the can often contains lead; canned meat foods are added sodium nitrite as a coloring agent, sodium nitrite can form nitrosamines with the amines in the protein. Fifth, processed meat foods mainly refers to luncheon meat, red sausage, square leg and sausage, etc.. Such foods must be added sodium nitrite (as a coloring agent to inhibit botulism and improve the flavor of food), in the storage process, it is likely to form nitrosamines. Nitrosamines: nitrite and protein decomposition of amines formed by the combination of a class of compounds, many varieties of more than ten. A large dose (greater than 25 mg/kg) can cause acute liver necrosis. Multiple small doses, causing cell mutations, can lead to a variety of cancers. Sources: 1, growing in saline land or the lack of molybdenum in the soil can contribute to the increase of nitrite in plants; 2, ammonium nitrate as artificial fertilizer; 3, when vegetables are pickled, nitrate is reduced to nitrite by bacteria, (4 hours after pickling began to increase, reaching a peak of 20 days, and began to decrease after 1 month); 4, added to meat products as a coloring agent. Usually eat less or do not eat foods with high nitrosamine content: 1, cooked vegetables should not be stored for a long time; 2, avoid salted vegetables (containing nitrite) and animal food (yellowtail, squid fish, shredded meat, etc.) cooked together; 3, eat less or do not eat canned meat products (luncheon meat, red sausage, square leg) and sausages and other foods. Six, cream and animal offal Reasons: high fat content, too much saturated fatty acids; too much cholesterol, often eaten easily caused by hyperlipidemia (children can eat some animal liver in moderation) Seven, cream products Reasons: easily caused by hyperlipidemia Eight, frozen foods (such as ice cream, ice cream, etc.) The reason is that the cream content is too high, containing more low-molecular sugar, will stimulate insulin secretion; increase the burden on the pancreas, inducing diabetes And the temperature is too low, it will make the digestive tract vasoconstriction, intestinal peristalsis accelerated, the secretion of digestive juices reduced, weakening the digestive function. Nine, instant noodles Reason: high fat, high salt, low vitamins, low minerals, but also contains a large number of preservatives and flavors. The proportion of nutrients and the actual needs of the human body is very different. Ten, preserves contain a large amount of salt, color, saccharin and preservatives; strong stimulation of the taste buds, often eat preserves will reduce the sensitivity of the palate, leading to a decrease in appetite.