Branched Chain Amino Acids (BCAAs)

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.


A. Bipolar Disorder

A1. 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.

B. Hepatic Encephalopathy

B1. Gluud LL, Dam G, et al. Branched-chain amino acids for people with hepatic encephalopathy. Cochrane Database Syst Rev. 2017;5:CD001939.

C. Liver Cancer

C1. 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.

C2. 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.

D. Liver Transplant Support

D1. Langer G, Großmann K, et al. Nutritional interventions for liver-transplanted patients. Cochrane Database Syst Rev. 2012 Aug 15;(8):CD007605.

E. Muscle Soreness or Growth

E1. 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.

E2. 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.

E3. 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.

E4. 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.

E5. 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.

F. Porto-systemic Encephalopathy

F1. 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.

G. Safety

G1. 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.

Last reviewed December 2019 by EBSCO NAT Review Board Eric Hurwitz, DC
Last Updated: 12/3/2019

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