Proteins have a variety of roles in the human body, including constituting the structure of human cells and organisms, material transportation, catalytic function, information exchange, immune function, oxidative energy supply, maintaining the acid-base balance of the body, and maintaining normal plasma osmolality. 1. Composition of human cells and organism structure: human muscle, viscera, nerves, blood, bones, including skin, hair are rich in protein. Proteins are important components of cells, such as chromosomal proteins and membrane proteins. 2. Material transport: such as hemoglobin can carry oxygen to all parts of the body for tissue cell metabolism. 3. Catalytic function: there are a large number of enzyme-catalyzed chemical reactions in the human body, life activities can not be separated from the enzyme, and the vast majority of enzymes are proteins. 4. Information exchange: exist in the cell membrane so that the cells of the external stimulus to produce the corresponding effect of the receptor is protein, can be converted to external stimuli for the body reaction. 5. Immune function: to protect the body against the infection of the corresponding pathogens, antibodies, lymphokines and other immune molecules are proteins. 6. Oxidative energy supply: proteins in the body can be completely oxidized and decomposed into water, carbon dioxide, and release energy. 7. Maintain the acid-base balance of the body: protein buffer system is an important part of the blood buffer system, which is conducive to maintaining the acid-base balance of the body. 8. Maintain normal plasma osmotic pressure: plasma colloid osmotic pressure is mainly composed of protein molecules, which can maintain the balance of material exchange between plasma and tissue fluid. Therefore, the role of protein on the human body is many, when the body exists disease or malnutrition will lead to a reduction in the body’s protein content, from a variety of aspects to the human body to bring about adverse effects, should seek medical attention in a timely manner, early treatment.