(2) the role of nutrients. Alpha protein. Protein is one of the most basic substances in life and an important component of tissues and cells, and its content accounts for about 45% of the total solid of human body. Used for the regeneration, renewal and repair of tissue cells; Regulate physiological functions and participate in substance metabolism; The function of providing some energy needed by the human body. 65,438+00% ~ 65,438+05% of the daily calories of human body come from protein. B is fat. Fat is the nutrient with the highest calorie content in human body. Phosphorus and nitrogen in fat are essential substances for cell formation, transformation and growth. Its main functions are: providing heat; Protect internal organs; Maintain body temperature; Assist the absorption of fat-soluble vitamins; Participate in metabolic activities in all aspects of the body. C carbohydrates. Carbohydrate, also known as sugar, is the main source of human thermal energy and the main component of nerve tissues and cells, and participates in many life activities in the body. You can't eat too much sugar, because too much sweets may affect the supplement of protein, minerals and vitamins; It can reduce the content of vitamin B 1 in the body, reduce the activity ability of nerves and muscles, and occasionally fall and fracture easily. Vitamin D Vitamin is an essential organic substance to maintain human life activities and an important active substance to maintain human health. Because the content of vitamins in the body is very small, it plays an important role in the process of human growth, metabolism and development. E minerals. Minerals, also known as inorganic salts, are the general name of inorganic substances in human body and are essential elements for human body. There are about 50 minerals in the human body. Although it only accounts for 4% of the body weight, it is an indispensable part of the human body. Minerals can't be produced and synthesized by themselves, they are all taken from food. Insufficient intake will affect human metabolic activities, and excessive intake will easily lead to poisoning, so we must pay attention to proper intake of minerals. F dietary fiber. Dietary fiber, also known as crude fiber, has few nutrients, is not easy to digest and absorb, can control weight, can also increase the volume of feces, reduce the time for food residues to stay in the human body in the intestine, and accelerate the frequency of defecation. Foods containing crude fiber mainly include grains, vegetables, fruits and beans. G water. Water is an important part of various cells and body fluids in the human body, and many physiological activities of the human body can only be carried out with the participation of water. Water is a transportation medium, which can directly or indirectly bring oxygen and various nutrients to various tissues and organs of the human body; Water excretes metabolic wastes and harmful and toxic substances in time through defecation, sweating and breathing; Water is the lubricant of human body, which makes various tissues and organs of human body move flexibly and food can be swallowed; Water also plays an important role in regulating acid-base balance and body temperature.