Branched-chain amino acids / BCAAs

Also known as BCAA, leucine isoleucine valine, branch chain amino acids.

Last reviewed October 9, 2026 · Jump to references

What is Branched-chain amino acids / BCAAs?

In plain words

BCAAs are three amino acids, the building blocks of protein, that the body must get from food. The body uses them to build proteins and can break them down for energy. Researchers study BCAA supplements for muscle maintenance, exercise recovery, and muscle soreness. Evidence that they provide extra benefits beyond enough complete dietary protein is limited.

Technical definition

Branched-chain amino acids (BCAAs) are the essential proteinogenic amino acids leucine, isoleucine, and valine, characterized by branched aliphatic side chains and obtained from dietary protein. They serve as substrates for protein synthesis and energy metabolism; leucine also promotes mTORC1 signaling, a nutrient-sensing pathway that regulates protein synthesis, rather than acting through a single dedicated receptor. In the United States, BCAAs are marketed as dietary supplements, which do not require FDA approval for efficacy before sale.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.