From a nutritional point of view, high-quality protein must meet three conditions: 1) the variety of essential amino acids must be complete; 2) the ratio of essential amino acids must be appropriate; 3) the quantity of essential amino acids must be sufficient. The amino acid pattern of protein that meets these three conditions is the closest to the amino acid pattern of human protein and can be better metabolized, absorbed and utilized by the body. The representative foods of high quality protein are milk, eggs, meat, fish and soy foods, and the protein contained in these types of foods is called high quality protein.