Leucine is one of the essential amino acids that belongs to the category of BCAAs, i.e., branch-chain amino acids. Amino acids are organic molecules consisting of a carboxylic group (COOH), an amino group (NH2), a hydrogen molecule (H) and a radical group, all interconnected thanks to a central carbon atom. The radical group varies according to the amino acid.

As this amino acid is not synthesized by the body, it has to be obtained exclusively through the diet or dietary supplements. Leucine is mainly present in items, such as: nuts, rice, whole wheat, cheese, chicken and fish.