[Medical Q&A] Does a high protein content mean it is a high-quality protein food?

Planner: Chinese Medical Association

Reviewer: Gong Weiyan, Associate Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention

Protein is a very important nutrient and an important material basis for life. I believe many people have heard the term "high-quality protein". The reason why it is called "high-quality" does not mean that the protein content of the food is high. To answer this question, we need to understand it from a microscopic level.

Amino acids are the basic units that make up proteins, which are connected by peptide bonds and form a certain spatial structure. There are more than 20 kinds of amino acids that make up human proteins, of which 9 cannot be synthesized by the human body and must be obtained from food, which are called "essential amino acids". For adults, there are 8 kinds, namely isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine; for infants, histidine is an essential amino acid. Other than essential amino acids are non-essential amino acids (the body can use some precursor substances to synthesize them). The proportion of amino acids that make up proteins in various tissues and cells of the human body is certain. This composition ratio is called the amino acid pattern, and the amino acid patterns of different foods are not the same. If a certain food contains all the essential amino acids needed by the human body, and the closer the amino acid pattern of its protein is to the amino acid pattern of human protein, then the protein of this food is easier to be absorbed and used by the human body, and this food can be called high-quality protein food, such as eggs, milk, fish and soy protein. Eating more high-quality protein foods means that the human body can efficiently use the amino acids in these foods to synthesize proteins, thereby maintaining good health.