Branched Chained Amino Acids (BCAAs)
Brief description
BCAAs are made up of three main amino acids – leucine, isoleucine and valine. These amino acids have a branched chain and have been studied for their role in muscle synthesis, but also in other conditions, such as liver cirrhosis, renal failure, sepsis, trauma, burns and cancer.
BCAAs are present in large concentrations within muscle tissue compared to other types of amino acids. They can only be obtained from the diet (i.e our body does not produce them).
You can increase your intake of BCAAs, particularly leucine, by including the following in your diet: meat & poultry: chicken, beef, turkey; Fish: tuna, salmon; dairy: milk, cheese, cottage cheese and eggs.
BCAAs are used for protein synthesis or energy production and are particularly involved in activation of the mammalian target of rapamycin (mTOR) signalling pathway (our most accepted pathway for muscle protein synthesis)(1).
Evidence Base
Reduction in delayed onset muscle soreness (DOMS): A 2024 systematic review of 18 trials found that BCAA supplementation was able to significantly reduce the effect of DOMS at 24 hrs, 48hrs, 72hrs and 96hrs. The trial found that a longer supplementation period also reduced the effect of DOMS at the 24-hour mark(2). Older systematic reviews and meta-analysis seem to reinforce these updated findings(3-5).
There is not enough current evidence suggesting an improvement in muscle mass or strength(6, 7).
Recommended serving & duration.
It is possible that of the BCAAs, it is leucine that is the most potent activator of the mTOR1 pathway.
The standard dosage of leucine ranges from 2-10grams.
It is suggested BCAA dosages should be around 20g – with a balanced ratio of leucine and isoleucine.
However, supplementation may not be necessary if enough BCAAs are provided through the diet(8).
Safety & tolerability
From the papers identified, there is no indication that BCAA supplementation causes harm. Generally, supplementation is well tolerated.
There is growing research suggesting BCAA levels in the blood can be a marker of insulin resistance (a risk factor for diabetes)(9, 10). However, research is yet to determine whether supplementation increases this risk.
alterations in blood plasma, and as supplements.
References
Holeček M. Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. Nutr Metab (Lond). 2018;15:33.Salem A, Ben Maaoui K, Jahrami H, AlMarzooqi MA, Boukhris O, Messai B, et al. Attenuating Muscle Damage Biomarkers and Muscle Soreness After an Exercise-Induced Muscle Damage with Branched-Chain Amino Acid (BCAA) Supplementation: A Systematic Review and Meta-analysis with Meta-regression. Sports Med Open. 2024;10(1):42.Martinho DV, Nobari H, Faria A, Field A, Duarte D, Sarmento H. Oral Branched-Chain Amino Acids Supplementation in Athletes: A Systematic Review. Nutrients. 2022;14(19).Fedewa MV, Spencer SO, Williams TD, Becker ZE, Fuqua CA. Effect of branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis. Int J Vitam Nutr Res. 2019;89(5-6):348-56.Weber MG, Dias SS, de Angelis TR, Fernandes EV, Bernardes AG, Milanez VF, et al. The use of BCAA to decrease delayed-onset muscle soreness after a single bout of exercise: a systematic review and meta-analysis. Amino Acids. 2021;53(11):1663-78.Wolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? Journal of the International Society of Sports Nutrition. 2017;14(1):30.Kerksick CM, Wilborn CD, Roberts MD, Smith-Ryan A, Kleiner SM, Jäger R, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition. 2018;15(1):38.Katherine Nguyen GL. Branched Chained Amino Acids (BCAAs) Examine.com: Examine.com; 2025 [Available from: https://examine.com/supplements/branched-chain-amino-acids/?show_conditions=true#dosage-information.Zhao X, Han Q, Liu Y, Sun C, Gang X, Wang G. The Relationship between Branched-Chain Amino Acid Related Metabolomic Signature and Insulin Resistance: A Systematic Review. J Diabetes Res. 2016;2016:2794591.Ramzan I, Ardavani A, Vanweert F, Mellett A, Atherton PJ, Idris I. The Association between Circulating Branched Chain Amino Acids and the Temporal Risk of Developing Type 2 Diabetes Mellitus: A Systematic Review & Meta-Analysis. Nutrients. 2022;14(20).
