Protein metabolism is a description of the physical and chemical processes that cause both the building, or synthesis, of amino acids into proteins and the breakdown, or catabolism, of proteins into amino acids. Amino acids are circulated through the blood and enter the body tissues, where they are synthesized back into protein. Balance between protein synthesis and catabolism is essential to maintain normal cell functioning.
Soft tissues require amino acids to manufacture the types of proteins needed for maintenance of life processes. Amino acid synthesis is necessary to form other essential compounds in the body, like histamine, neurotransmitters, and components of nucleotides. Any amino acids that are left over after synthesis are either stored as fat or converted into energy.
Amino acids can be classified as essential and non-essential. Essential amino acids cannot be made by the body but are essential to protein metabolism. These amino acids must be acquired from food. Non-essential amino acids are required for normal cell functioning and can be synthesized from other amino acids in the body. Once the proper amino acids are acquired, they combine to provide proteins the body tissues can use.
The liver is the center for breaking down needed proteins and sending the required amino acids into the blood. It constantly monitors and responds to the body’s protein needs. The liver is also responsible for processing and excreting the waste products that are produced as a by-product of protein metabolism.
Some people feel that consuming high-protein diets will help them lose weight faster and maintain muscle mass. The truth is that most people consume too much protein and place unnecessary strain on the body in doing so. The body will turn excess protein into fat, just as it will with carbohydrate and dietary fat. Excess protein in the diet will also cause more protein metabolism to occur, which produces waste products that must be disposed of.
Since ingested proteins are broken down and reassembled before getting used in the various parts of the body, eating foods containing certain amino acids does not necessarily mean that the body will use that amino acid in the form the individual intends it. For example, some people attempt to supplement with certain types of protein hoping to benefit from their health effects. This does not work the way the person intends it because the body controls protein metabolism by breaking down proteins and reassembling them with other amino acids to best satisfy the needs of the body.