Supplement Forms/Alternate Names:

  • BCAAs, leucine, isoleucine, valine

Branched chain amino acids (BCCAs) refers to a group of proteins with a branch-like structure. These proteins are used to rebuild muscle. BCCAs have been used to ease muscle soreness and improve muscle function. They can be taken as a pill or powder. They can also be injected into the bloodstream by a healthcare provider.

1 to 5 grams once daily.

What Research Shows

May Be Effective

  • Hepatic encephalopathy—may reduce symptoms B1
  • Muscle soreness—may ease muscle pain after vigorous exercise E1-E3

Not Enough Data to Assess

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take branched chain amino acids in small doses for a short time, but nausea and vomiting are possible. It may also increase the risk of diabetes. G1 Not enough studies have been done to say whether it is safe to take for a long period. It is also not known whether it is safe to take by women who are pregnant or breastfeeding.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.


REFA Bipolar Disorder

REFA1 Sarris J, Mischoulon D, et al. Adjunctive nutraceuticals with standard pharmacotherapies in bipolar disorder: a systematic review of clinical trials. Bipolar Disord. 2011 Aug-Sep;13(5-6):454-465.

REFB Hepatic Encephalopathy

REFB1 Gluud LL, Dam G, et al. Branched-chain amino acids for people with hepatic encephalopathy. Cochrane Database Syst Rev. 2017;5:CD001939.

REFC Liver Cancer

REFC1 Meng J, Zhong J, et al. Pre-, peri-, and postoperative oral administration of branched-chain amino acids for primary liver cancer patients for hepatic resection: a systematic review. Nutr Cancer. 2014;66(3):517-522.

REFC2 Chen L, Chen Y, et al. Efficacy and safety of oral branched-chain amino acid supplementation in patients undergoing interventions for hepatocellular carcinoma: a meta-analysis. Nutr J. 2015 Jul 9;14:67.

REFD Liver Transplant Support

REFD1 Langer G, Großmann K, et al. Nutritional interventions for liver-transplanted patients. Cochrane Database Syst Rev. 2012 Aug 15;(8):CD007605.

REFE Muscle Soreness or Growth

REFE1 Rahimi MH, Shab-Bidar S, et al. Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials. Nutrition. 2017;42:30-36.

REFE2 Fouré A, Bendahan D. Is Branched-Chain Amino Acids Supplementation an Efficient Nutritional Strategy to Alleviate Skeletal Muscle Damage? A Systematic Review. Nutrients. 2017 Sep 21;9(10). pii: E1047.

REFE3 Fedewa MV, Spencer SO, et al. Effect of branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis. Int J Vitam Nutr Res. 2019;2:1-9.

REFE4 Aguiar AF, Grala AP, da Silva RA, et al. Free leucine supplementation during an 8-week resistance training program does not increase muscle mass and strength in untrained young adult subjects. Amino Acids. 2017 Jul;49(7):1255-1262.

REFE5 Wiśnik P, Chmura J, Ziemba AW, Mikulski T, Nazar K. The effect of branched chain amino acids on psychomotor performance during treadmill exercise of changing intensity simulating a soccer game. Appl Physiol Nutr Metab. 2011 Dec;36(6):856-62.

REFF Porto-systemic Encephalopathy

REFF1 Metcalfe EL, Avenell A, et al. Branched-chain amino acid supplementation in adults with cirrhosis and porto-systemic encephalopathy: systematic review. Clin Nutr. 2014 Dec;33(6):958-965.

REFG Safety

REFG1 Zheng Y, Li Y, et al. Cumulative consumption of branched-chain amino acids and incidence of type 2 diabetes. Int J Epidemiol. 2016 Oct;45(5):1482-1492.

Revision Information

  • Reviewer: EBSCO NAT Review Board Eric Hurwitz, DC
  • Review Date: 12/2019
  • Update Date: 12/03/2019