Essential amino acids are specific building blocks of proteins that must be supplied from outside, for example through food or supplements.

BCAA stands for branched-chain amino acids, that is, amino acids with a branched structure. They include three well-known amino acids: leucine, isoleucine, and valine. They are called ‘essential’ because they do not arise naturally in food, but must be added separately.

The 2:1:1 ratio (leucine:isoleucine:valine) corresponds to how these amino acids often occur together in natural protein sources. It is a widely used ratio in powders and supplements.

The ‘L’ indicates the natural form of the amino acid, as also found in food. Amino acids come in an L- and a D-form, but only the L-forms are generally used in foods and supplements.