What is BCAA (branched-chain amino acids)? Uses, side effects, and more.


Branched-chain amino acids (BCAAs) are essential nutrients including leucine, isoleucine, and valine. They’re found in meat, dairy, and legumes.

BCAAs stimulate the building of protein in muscle and possibly reduce muscle breakdown. The “Branched-chain” refers to the chemical structure of these amino acids.

BCAAs are used for reduced brain function in people with advanced liver disease and for a movement disorder often caused by antipsychotic drugs. They are also commonly used to improve athletic performance, prevent fatigue, reduce muscle breakdown, and other purposes, but there isn’t enough reliable information to support these other uses.

Possibly effective for

  • Reduced brain function in people with advanced liver disease. Taking BCAAs by mouth seems to improve liver function in people with poor brain function caused by liver disease.
  • A movement disorder often caused by antipsychotic drugs. Taking BCAAs by mouth seems to reduce symptoms of this condition in adults and children taking antipsychotic drugs.

Possibly ineffective for

  • Liver cancer. Taking up to 50 grams of BCAAs by mouth twice daily for up to one year does not seem to improve outcomes in people with liver cancer who have had surgery.

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