Branched-Chain Amino Acids
Branched-chain amino acids (BCAAs) are three essential amino acids that are frequently supplemented because of their role in muscle growth and development. These amino acids are naturally found in dietary protein sources. Studies show that supplementation of BCAAs alone does not increase muscle growth, as all essential amino acids must be present for muscle protein synthesis to occur.
Branched-Chain Amino Acids is most often used for
Last Updated:July 22, 2023
BCAAs refer to three essential amino acids: leucine, isoleucine, and valine. They are distinct from other essential amino acids as they possess a branched side chain and play a large role in the regulation of muscle mass. They are present in high amounts in muscle tissue in comparison to other essential amino acids.[1] BCAAs cannot be synthesized in the body, so they are important to ingest daily. Daily protein sources, such as eggs and meat, typically provide an adequate amount.[2]
The main benefit of BCAAs are their ability to enhance muscle growth and alleviate muscle fatigue. Studies found that supplementing with BCAAs alone does not provide an optimal muscle protein synthesis response, as all essential amino acids are required for muscle protein synthesis.[3][4] There seems to be a role for BCAA supplementation in increasing muscle protein synthesis if they are taken along with a meal that has an adequate amount of essential amino acids.[4] However, there is no evidence that BCAA supplementation enhances muscle strength or hypertrophy when adequate protein requirements are met.[2] BCAA supplementation for fatigue may be beneficial, based on a meta-analysis of BCAA effects on markers of muscle damage. The results found that BCAA supplementation reduced muscle damage and muscle soreness after exercise, but may not speed up the recovery of muscle performance.[5]
There is a growing interest in understanding the correlation between the amount of BCAAs present within the body and insulin resistance. In insulin resistant states, such as in people with obesity, there appear to be higher circulating levels of BCAAs.[6] However, serum BCAAs seem to be more of a biomarker of insulin resistance, and their potentially causative role is not well understood and requires further research.
Amino acids are the building blocks of proteins, and adequate amounts of all essential amino acids are required for adequate protein synthesis. BCAAs alone do not promote muscle protein synthesis.[3]
- BCAAs
- BCAA
- Leucine
- Isoleucine
- or Valine (all individual BCAAs)
The three BCAAs are leucine, isoleucine, and valine. They’re considered the most anabolic of the nine essential amino acids and have therefore been marketed as a sports supplement. However, it's possible that only leucine is especially anabolic, and that leucine taken alone is actually more anabolic than leucine taken with isoleucine and valine, due to competition for both absorption in the gut and entry into muscle tissue.
The standard leucine dosage is 2–10 grams. The standard dosage for isoleucine is 48–72 milligrams per kilogram of bodyweight, assuming a non-obese person. Further research is needed to determine valine’s optimal dosage and the reason for supplementation.
A combination dose is 20 grams of combined BCAAs, with a balanced ratio of leucine and isoleucine.
Supplementation with BCAAs is not necessary if enough BCAAs are provided through the diet.
- ^Shimomura Y, Yamamoto Y, Bajotto G, Sato J, Murakami T, Shimomura N, Kobayashi H, Mawatari KNutraceutical effects of branched-chain amino acids on skeletal muscle.J Nutr.(2006-Feb)
- ^Daniel L Plotkin, Kenneth Delcastillo, Derrick W Van Every, Kevin D Tipton, Alan A Aragon, Brad J SchoenfeldIsolated Leucine and Branched-Chain Amino Acid Supplementation for Enhancing Muscular Strength and Hypertrophy: A Narrative ReviewInt J Sport Nutr Exerc Metab.(2021 May 1)
- ^Wolfe RRBranched-chain amino acids and muscle protein synthesis in humans: myth or reality?J Int Soc Sports Nutr.(2017 Aug 22)
- ^Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KDBranched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in HumansFront Physiol.(2017 Jun 7)
- ^Kenji Doma, Utkarsh Singh, Daniel Boullosa, Jonathan Douglas ConnorThe effect of branched-chain amino acid on muscle damage markers and performance following strenuous exercise: a systematic review and meta-analysisAppl Physiol Nutr Metab.(2021 Nov)
- ^Christopher J Lynch, Sean H AdamsBranched-chain amino acids in metabolic signalling and insulin resistanceNat Rev Endocrinol.(2014 Dec)
- Cortisol - Portier H, Chatard JC, Filaire E, Jaunet-Devienne MF, Robert A, Guezennec CYEffects of branched-chain amino acids supplementation on physiological and psychological performance during an offshore sailing raceEur J Appl Physiol.(2008 Nov)
- Fatigue Symptoms - Blomstrand E, Hassmén P, Newsholme EAEffect of branched-chain amino acid supplementation on mental performanceActa Physiol Scand.(1991 Oct)
- Fatigue Symptoms - Blomstrand E, Hassmén P, Ekblom B, Newsholme EAAdministration of branched-chain amino acids during sustained exercise--effects on performance and on plasma concentration of some amino acidsEur J Appl Physiol Occup Physiol.(1991)
- Aerobic Exercise Metrics - Gualano AB, Bozza T, Lopes De Campos P, Roschel H, Dos Santos Costa A, Luiz Marquezi M, Benatti F, Herbert Lancha Junior ABranched-chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletionJ Sports Med Phys Fitness.(2011 Mar)
- Aerobic Exercise Metrics - van Hall G, Raaymakers JS, Saris WH, Wagenmakers AJIngestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performanceJ Physiol.(1995 Aug 1)
- Ammonia - Shimomura Y, Inaguma A, Watanabe S, Yamamoto Y, Muramatsu Y, Bajotto G, Sato J, Shimomura N, Kobayashi H, Mawatari KBranched-chain amino acid supplementation before squat exercise and delayed-onset muscle sorenessInt J Sport Nutr Exerc Metab.(2010 Jun)
- Heart Rate - Blomstrand E, Hassmén P, Ek S, Ekblom B, Newsholme EAInfluence of ingesting a solution of branched-chain amino acids on perceived exertion during exerciseActa Physiol Scand.(1997 Jan)
- Weight - Bigard AX, Lavier P, Ullmann L, Legrand H, Douce P, Guezennec CYBranched-chain amino acid supplementation during repeated prolonged skiing exercises at altitudeInt J Sport Nutr.(1996 Sep)
- Fat Oxidation - Wiśnik P, Chmura J, Ziemba AW, Mikulski T, Nazar KThe effect of branched chain amino acids on psychomotor performance during treadmill exercise of changing intensity simulating a soccer gameAppl Physiol Nutr Metab.(2011 Dec)
- Muscle Soreness - Shimizu M, Miyagawa K, Iwashita S, Noda T, Hamada K, Genno H, Nose HEnergy expenditure during 2-day trail walking in the mountains (2,857 m) and the effects of amino acid supplementation in older men and womenEur J Appl Physiol.(2012 Mar)