Diet therapy is called "food support" for short. That is, the use of food affects all aspects of the body's functions, making it healthy or preventing diseases. As the saying goes, it is to eat to maintain our health. It is generally believed that food is an edible substance that provides various nutrients for human growth and healthy survival. In other words, the most important function of food is nutrition. In fact, Chinese medicine has long recognized that food can not only nourish, but also cure diseases. For example, Zhang Xichun, a modern physician, once pointed out in The Enthusiasm of Western Medicine that food "can cure diseases and satisfy hunger; It can not only satisfy hunger, but also be palatable and treat symptoms. The disease is gradually recovering, that is, it is not symptomatic and there is no other disease. " With the development of society, people pay more and more attention to the way of health preservation. Many foods suitable for health care have also been promoted, such as health care miscellaneous grains powder, miscellaneous grains porridge, medicated diet and so on.