BCAA

Any of a large group of organic compounds marked by the presence of both an amino (NH₂) group and a carboxyl (COOH) group. Amino acids are the building blocks of proteins and the end products of protein digestion.

Approximately 80 amino acids are found in nature, but only 20 are necessary for human metabolism or growth. Of these, some can be produced by the liver; the rest, the “'essential' amino acids, ” must be supplied by food. Oral preparations of amino acids may be used as dietary supplements.

Arginine is nonessential for adults but cannot be formed quickly enough to supply the demand in infants and thus is classed as essential in early life.

Some proteins containing all the essential amino acids are called complete proteins. Examples are milk, cheese, eggs, and meat. Proteins that do not contain all the essential amino acids are called incomplete proteins. Examples are vegetables and grains. Amino acids pass unchanged through the intestinal wall into the blood, then through the portal vein to the liver and into the general circulation, from which they are absorbed by the tissues according to the specific amino acid needed by that tissue to make its own protein. Amino acids, if not otherwise metabolized, may be converted into urea. See: deaminization; digestion; protein

The essential amino acids, leucine, isoleucine, and valine. “Branched-chain” refers to their chemical structure. They are therapeutically valuable because they bypass the liver and are available for cellular uptake from the circulation. Parenteral administration, alone or mixed with other amino acids, is thought to be beneficial whenever catabolism due to physiological stress occurs. Skeletal muscles use BCAAs for their anticatabolic effects.

An amino acid that becomes essential under specific clinical conditions, e.g., when their rate of synthesis is limited.

An amino acid that is required for growth and development but that cannot be produced by the body and must be obtained from food. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, cysteine, phenylalanine, tyrosine, threonine, tryptophan, and valine. Synonym: indispensable amino acid

An amino acid that can be produced by the body and is not required in the diet. The nonessential amino acids are alanine, aspartic acid, arginine, citrulline, glutamic acid, glycine, hydroxyglutamic acid, hydroxyproline, norleucine, proline, and serine.

An amino acid of which an adequate amount must be consumed in the diet to prevent the use of essential amino acids to synthesize it. An example is tyrosine. Without adequate dietary intake, the essential amino acid phenylalanine is used to make tyrosine.

The essential amino acids, leucine, isoleucine, and valine. “Branched-chain” refers to their chemical structure. They are therapeutically valuable because they bypass the liver and are available for cellular uptake from the circulation. Parenteral administration, alone or mixed with other amino acids, is thought to be beneficial whenever catabolism due to physiological stress occurs. Skeletal muscles use BCAAs for their anticatabolic effects.

See also: amino acid