Chinese medicine pays attention to "homology of medicine and food". Everyone knows the legend that Shennong tasted a hundred herbs. The book "Huai Nan Zi Xiu Wu Xun" said that Shennong "tasted the taste of a hundred herbs and the sweetness and bitterness of the water spring, which made the people know and avoid it. At this time, I encountered 70 poisons a day. " Knowing how to avoid it means knowing the basic properties and toxicity of herbs. It can be seen that there is no distinction between medicine and food in Shennong era. Those who are non-toxic can do it, and those who are toxic should avoid it. Therefore, many scholars also regard this as the earliest origin of the important thought of traditional Chinese medicine "homology of medicine and food" Since Suiren, human beings have learned to use fire and entered the era of cooked food. With the development of cooking technology, food and medicine began to differentiate. Huangdi Neijing is the earliest extant classic of traditional Chinese medicine, which establishes the concept of five flavors of food, the theory of five internal organs, the principle of dividing five categories of food, and the principles and taboos of drug and food preparation. Huangdi Neijing, Su Wen and Six Stages of Dirty Elephants pointed out that "there are five flavors in eating people in the ground" and "five flavors are hidden in the stomach. Taste Tibetan, to nourish five qi, qi is harmonious, body fluid is complementary, and god is born. " Five flavors, here mainly refers to food. Like medicine, food has five flavors: pungent, sour, sweet, bitter and salty, which are related to the five internal organs. In other words, five grains (wheat, millet, millet, rice and beans) and five domestic animals (chicken, sheep, cow, horse and hen) all have their own taste characteristics, which are related to the functions of the five internal organs respectively. For example, Su Wenjin Kui Yan Zhen said: "Oriental blue enters the liver, opens the eyes and stores essence. According to the theory of traditional Chinese medicine, the cereal with corresponding taste can promote and maintain the viscera. Because there is a complementary relationship between the five internal organs, the combination of the five flavors and the five internal organs may damage and harm the five internal organs. " Su Wen Wu Zang Gen Pian is devoted to "the injury of five flavors": "Eating more salty makes the pulse coagulate and change color, (sad); "If you eat too much, your skin will wrinkle and your hair will pull out" (lung injury); "Eating too much irritating food will make your muscles anxious and your paws dry" (damaging your liver); "Eating too much acid will wrinkle the skin and expose the lips" (injury to the spleen); "Eating too much sweets will lead to bone pain" (kidney injury). Because of the corresponding relationship between the five zang-organs and the five flavors, the morbid state can be treated and adjusted through the restraint between the five flavors, so "the liver is bitter and urgent, and it is slow to eat when it is urgent", "the heart is bitter and slow, and it is sour when it is urgent" and "the spleen is bitter and wet, and it is bitter and dry when it is urgent". But the difference of the five flavors will of course have their own different functions. The so-called "pungent, sour, sweet and slow, bitter and firm, salty and soft" should foster strengths and avoid weaknesses so as not to cause harm. Huangdi Neijing also specifically mentioned that "regulating food and medicine" should be used to treat diseases, that is, "five grains should be used to support, five fruits should be used to help, five livestock should be used to benefit, five dishes should be used to supplement, and smells should be combined to supplement essence". In the era of the birth of Huangdi Neijing, the earliest recorded medical officer appeared in the imperial court-"Food Doctor". It is clearly stipulated in Zhou Li Tianguan Zhi that the duty of food doctor is to prepare the emperor's "six drinks, six meals and a hundred sauces". It can be seen that a food doctor is not only a medical officer in charge of diet, but also knows how to regulate the health of the emperor with a diet with preventive and therapeutic effects. It can be seen from Zhou Li's emphasis on "five flavors, five grains and five medicines to nourish their diseases" that the combination of medicine and food was an important school to treat diseases and preserve health at that time. The four-season application principle of medicine and food distribution mentioned in the Book of Rites, that is, "more acid in spring, more bitter in summer, more pungent in autumn and more salty in winter", is a further development of the theory of "homology of medicine and food". In the book of songs, the first collection of poems in China, some articles that are both food and medicine are also recorded. There are some detailed descriptions in Shan Hai Jing, such as "Guo Jia is actually like a peach with leaves like dates and yellow flowers are red and orange, so it takes no effort to eat"; "Pears, with red leaves like flowers, can produce gangrene"; "Young birds, like birds, are visible to the naked eye and have a red tail, which is suitable for eating." These descriptions show that at that time, people have gained a lot of practical experience in using diet for preventive health care and improving physical fitness. The earliest pharmaceutical monograph in China, Shen Nong Ben Cao Jing, contains 365 kinds of drugs, which are divided into three categories according to their functions and purposes of use. Among them, "one hundred and twenty kinds of drugs are king, and the main life is for daily needs, which is non-toxic and does not hurt people after long-term service." Those who want to lighten the skin, benefit the qi and prolong life should go to menstruation. " It can be seen that the top-grade medicinal materials listed in Shennong Herbal Classic are both medicine and food. Treatise on Febrile Diseases, written by Zhang Zhongjing in Han Dynasty, is called "the ancestor of prescriptions" and is a model of TCM syndrome differentiation and treatment. Many prescriptions, such as white tiger soup with japonica rice, lily egg soup with yellow soup, and huangqi Jianzhong soup with maltose, are all examples of homology of medicine and food. Sun Simiao, a drug king born in Jin and Tang Dynasties, insisted on keeping food in view of the adverse effects of alchemy at that time. In the 26th volume of Qian Jin Fang Yao, he devoted himself to food supplement and food supplement, involving 162 kinds of food supplement materials. He created many famous dietotherapy recipes and put forward many dietotherapy principles, arguing that "he who doesn't know what he eats is not enough for his whole life;" There is no cure for those whose properties are unknown. Therefore, food can dispel evil and fix dirty, and drugs can nourish the mind and replenish the nature to enrich the four qi. " "Your father is ill, you should order some food for treatment first; Dietotherapy can't be cured, and then life medicine. "Compendium of Materia Medica is a masterpiece of pharmacy in Ming Dynasty, which almost records all kinds of cereals, fruits and vegetables that people use as food, and lists their effects. At the same time, the health and edible functions of other drugs are also discussed. To sum up, the so-called "homology of medicine and food" means that food not only provides energy and nutrition, but also plays an important and complicated role in maintaining health, regulating physical state and correcting abnormal conditions of the body. Therefore, strictly speaking, in Chinese medicine, medicine and food are inseparable and relative: medicine is also food, and food is also medicine; The side effects of food are small, but those of drugs are large. There is no clear line between medicine and food. Therefore, only a reasonable diet is the highest state of health.