Leucine, isoleucine and valine constitute the class of branched chained amino acids (BCAA) within the essential amino acid family.They are studied because of their potential role in slowing down tumour growth. Clinical studies in humans have shown a link between BCAA supplementation and length of survival.
The body is unable to synthesise leucine, isoleucine and valine sufficiently quickly, so the animal’s needs must be met through its diet. The blood concentration of these three, more than other amino acids, varies depending on intake.
Valine, leucine and isoleucine are able to stimulate the synthesis of proteins and slow down their degradation in the muscles. This property has been specifically attributed to leucine, which proves to be as effective on its own as a mixture of all three amino acids. Sensitivity to leucine appears to diminish with age. BCAAs help increase lean mass and prevent muscle atrophy in cachectic and cancer affected animals.
Valine, leucine and isoleucine represent at least one third of all essential amino acids in the composition of the muscle proteins. They are the only amino acids to be initially broken down by the muscles.