Branched-Chain Amino Acid (BCAA) Supplements: Myth Versus Reality

Are branched chain amino acid supplements worth your time and money? Separate fact from myth and learn what BCAAs are, and how they compare to whey protein.

Branched-chain amino acid (BCAA) supplements have received a lot of attention in recent years due to the mounting evidence both for and against their purported benefits.

That being said, it’s hard to argue with the fact that there is some merit to supplementing with BCAAs due to their inherent ability to positively regulate the mTOR pathway (which has implications on muscle protein synthesis).[1] They are also affordable and practically side effect free.

How BCAAs may help: BCAAs include the amino acids leucine, isoleucine, and valine.  Research has shown that L-leucine is a positive regulator of key enzymes in the mTOR pathway.[1] However, L-leucine on its own does not sufficiently increase muscle protein synthesis (it is more efficient in the presence of insulin and other EAAs).[2]

The primary benefits then are that BCAAs enhance muscle protein synthesis/muscle hypertrophy and promote recovery/reduce muscle damage during resistance training.[1,3]

Performing upright rows

Bear in mind that you should not be using BCAAs as a replacement for lack of protein intake from complete sources like animal and dairy proteins.

Deciphering BCAA facts from fiction

Fiction: BCAAs are superior to whey protein for maximizing muscle protein synthesis.

Fact: A study by Churchward-Venne et. al in 2012 actually showed that individuals who took 25g of whey protein isolate (providing 3g of leucine) exhibited a remarkably higher protein synthetic response than individuals who consumed suboptimal doses of protein “spiked” with extra leucine content or essential amino acids (even at equivocal amounts of leucine being provided to the different treatments).[4] Therefore, simply chugging BCAAs (or leucine) in the absence of a sufficiently dosed, complete/quality protein source is inferior to ingesting a nominal dose of said protein.

Fiction: BCAAs are calorie-free.

Fact: Amino acids actually provide about as much energy per gram as other peptide molecules/proteins (i.e. 4 calories per gram). So if your BCAA product contains a 5000mg “BCAA” blend that is about 20 calories per serving.

Fiction: BCAA supplements are pointless since you can simply get BCAAs through food sources.

Fact: BCAAs are free-form, unbound moieties and after ingestion result in rapid elevation of plasma amino acid levels, thus they are much quicker to be utilized. On the other hand, a protein from food needs to be digested/hydrolyzed to a degree before plasma amino acid levels rise. Not to mention that nobody is likely to crack open some Tupperware and start downing chicken breast in between sets or while they’re on the treadmill (i.e. BCAAs offer practicality).

Fiction: Drinking BCAAs during a fasting period will increase muscle protein synthesis.

Fact: Many people purport that BCAAs during a fasting period will essentially give you the ability to build muscle tissue since BCAAs are a necessity for triggering protein synthesis while reaping the physiological benefits of fasting, but the reality is that without the other “absent” essential amino acids you will not be doing much muscle building, not to mention this defeats much of the purpose of fasting to begin with. This is not to say that BCAAs are not useful during a fasting period (since they may provide benefits through other metabolic pathways), but just that they are not going to magically going to help you build muscle during a fast.

Fiction: Since L-leucine is a positive regulator of many enzymes in the mTOR pathway it is more efficient to just use bulk L-leucine powders instead of complete BCAA products. Moreover, the higher the ratio of L-leucine to L-isoleucine and L-valine, the better the BCAA product.

Fact: To start, the “more is better” attitude definitely does not apply when it comes to leucine intake. As noted earlier, the increase in anabolic response to complete protein ingestion is reasoning against the use of pure L-leucine. Furthermore, chronic supplementation with leucine has been shown to promote insulin sensitizing effects nonspecifically, which in an energy surplus could result in increased fat deposition.[5]

Another point to consider is that L- isoleucine appears to be responsible for the non-insulin dependent enhanced rate of glucose clearance/uptake into skeletal muscle tissue (via increase in GLUT-4 expression).[6] That’s just one example of why you can’t discount the benefits of the “other” two BCAAs (isoleucine and valine).

Fasted cardio

BCAAs include the amino acids leucine, isoleucine, and valine.  Research has shown that L-leucine is a positive regulator of key enzymes in the mTOR pathway

The “big question”: Do you need a BCAA supplement?

Need? No, but does that mean there is no use for BCAAs? Certainly not; like most any other supplement, you need to determine the cost-to-benefit ratio and find what suits your goals.

Bear in mind that you should not be using BCAAs as a replacement for lack of protein intake from complete sources like animal and dairy proteins. Get your diet in check first, and then consider using BCAAs to see if you notice an improvement in recovery and performance.


1) Blomstrand E, Eliasson J, Karlsson HK, Köhnke R. Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise. J Nutr. 2006 Jan;136(1 Suppl):269S-73S. Review. PubMed PMID: 16365096.

2) Suryawan A, Torrazza RM, Gazzaneo MC, Orellana RA, Fiorotto ML, El-Kadi SW, Srivastava N, Nguyen HV, Davis TA.Enteral leucine supplementation increases protein synthesis in skeletal and cardiac muscles and visceral tissues of neonatal pigs through mTORC1-dependent pathways. Pediatr Res. 2012 Apr;71(4 Pt 1):324-31. doi: 10.1038/pr.2011.79. Epub 2012 Feb 15. PubMed PMID: 22391631; PubMed Central PMCID: PMC3619200.

3) Howatson G, Hoad M, Goodall S, Tallent J, Bell PG, French DN. Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study. J Int Soc Sports Nutr. 2012 May 8;9(1):20. [Epub ahead of print] PubMed PMID: 22569039; PubMed Central PMCID: PMC3395580.

4) Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol. 2012 Mar 25.

5) Li X, Wang X, Liu R, Ma Y, Guo H, Hao L, Yao P, Liu L, Sun X, He K, Cao W, Yang X. Chronic leucine supplementation increases body weight and insulin sensitivity in rats on high-fat diet likely by promoting insulin signaling in insulin-target tissues. Mol Nutr Food Res. 2013 Feb 13.

6) Manders RJ, Little JP, Forbes SC, Candow DG. Insulinotropic and muscle protein synthetic effects of branched-chain amino acids: potential therapy for type 2 diabetes and sarcopenia. Nutrients. 2012 Nov 8;4(11):1664-78.