It can be seen that the juice of staple food, dishes and fruits can cure diseases, and the ancients have accumulated rich experience in dietotherapy. Dietotherapy, in a narrow sense, is to treat diseases, in a broad sense, it is to preserve health, protect health and prevent diseases, and the latter is more important. In ancient times, there was a doctor who specialized in diet and health care, called Shi Bu. The name "food doctor" comes from Zhou Li Tianguan Tsuzawa's book, in which officials in charge of medical care have four different responsibilities: food doctor, disease doctor (physician) and doctor of choice (surgeon) veterinarian.

The food doctor is responsible for regulating the cold temperature, taste and nutrition of the royal diet, and is quite a modern nutrition doctor. Doctor Zhang and Wang Zhi's six meals, six drinks, six meals, one hundred shames and one hundred sauces and eight treasures were served by two petty officers. About eating, shame, sauce and freshness, I have already introduced them in my essay "Talking about Diet". Cooking is a chef's job, and food doctors mainly coordinate food, drink, meal and shame to determine the cold temperature of diet, which can be compared with the temperature of the four seasons, that is, the staple food should be warm, the soup should be hot, the sauce should be cold, and the drinks and wine should be cold; The combination of five flavors and seasons also pays attention to eating sour in spring, bitter in summer, spicy in autumn and salty in winter.

Such a complicated and exquisite diet is for the children of heaven, princes and noble families, but it also fully shows that the ancients put forward a more systematic diet health-keeping and fitness method as early as 2000 years ago. In the palace, food doctors ranked first among all doctors, which also showed the importance attached to food supplement and diet therapy at that time. Although these practices are unscientific and incomplete, they still have their reference value. Later, medicine became more and more detailed, and the Yuan Dynasty was divided into thirteen families. Although the discipline of "food doctor" is no longer set up, food support and dietotherapy are accepted by the majority of medical staff, and the methods are also integrated into the treatment and health care of various disciplines. Xu Dachun, a famous doctor in the Qing Dynasty, pointed out in the article "Medication as Hard" that the reason why saints have a whole livelihood is because five grains are nourishment, five fruits are useless, five animals are beneficial, five dishes are stuffing, and poison is used to attack evil.