There are three branched-chain amino acids, leucine, isoleucine, and valine. The three branched-chain amino acids also make up one-third of the nine essential amino acids which must be consumed in our diet or via supplements.
There was a lot of interest generated around branched-chain amino acids after early research showed that these three amino acids have a unique ability to stimulate muscle protein synthesis, the process required for muscle growth and repair. Leucine specifically, is a direct precursor to muscle protein synthesis (think of it as an on switch) and regulates a number of anabolic signalling pathways that are involved with protein synthesis.
It’s important to note, however, that the predominance of research demonstrating a positive link between branched-chain amino acid intake and muscle protein synthesis has been conducted in rodents (limited application to human protein synthesis responses), and that although muscle protein synthesis may rise quite rapidly following consumption in rodents, the effect is relatively short-lived.
