Branched-chain amino acids (BCAAs) include leucine, isoleucine and valine—three of nine essential amino acids (EAAs) that the body cannot make on its own. Historically, BCAA supplements were held in high regard for their perceived impact on athletic performance. In recent years, BCAAs have come under fire for having little or no effect on aspects important to performance. These include muscle protein synthesis (MPS) and recovery. EAAs, on the other hand, are increasingly taking center stage with supplement companies promoting their net positive impact on neurotransmitters, hormones, enzymes and muscle tissue (Momentous, n.d.).

BCAAs and EAAs: More on the Debate

In Boundless, author Ben Greenfield (2020) states that claims about the benefits of BCAAs are primarily based on studies conducted on rats in 2006 (p. 50). He calls EAAs “far more efficacious,” and says that they boost brain and liver function and increase metabolic rate and lean muscle retention (Greenfield, 2020). Ironically, in a later chapter, Greenfield talks about how ingesting BCAAs—“preferably during workouts”—enhances performance, particularly that of the nervous system.

“These amino acids also improve physiological markers such as red blood cell count, hemoglobin, hematocrit, serum albumin, and fasting glucose, and they even decrease inflammatory markers like creatine phosphokinase while enhancing the restoration of muscle glycogen,” says Greenfield of BCAAs (Greenfield, 2020, p. 585).

BCAAs and EAAs: The Science

If we look at the recent science, it appears that both perspectives are “right.” A 2024 systemic review found that BCAA ingestion reduced both creatine kinase (CK) levels and muscle soreness. This finding led the authors to conclude that, “BCAA supplementation is an effective method to reduce post-exercise muscle damage biomarkers, particularly CK levels, and muscle soreness, with no effect on muscle performance” (Salem et al., 2024, Abstract).

Likewise, in 2023, the International Society of Sports Nutrition (ISSN) issued a position statement attesting the benefits of EAA supplementation in healthy, aging and clinical populations. Among the benefits was the role in stimulation of MPS (Ferrando et al., 2023). “Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS,” it says (Ferrando et al., 2023, Abstract).

We Need to Know More About Formulations

What does this mean for athletes who want to optimize performance or those simply looking to make the most of their physical training and time in the gym? First, it is important to acknowledge that BCAAs maintain some degree of efficacy and should not be entirely disregarded in favor of EAAs. Second, I believe that we need to further understand the role of leucine, as well as the ratios and dosing of the amino acids found within various formulas. Both of these considerations go beyond the scope of this forum post. Perhaps we will dive deeper another day!

Author’s Note

Hello, my friends and welcome! If you have been following my blog, you will know that this post is unlike my typical writing—personal, reflective and with a focus on mindset and how it relates to performance and often applies to real life! You may also know that as of last year, I am back to the books, pursuing a professional coaching certification and master’s degree in health and human performance.

This term, I am enrolled in a course on nutritional supplementation for peak performance. Each week, we are asked to post our thoughts and related research on a nutritional topic of interest. With that as context, I have decided to share my posts here with you!

What you need to know

The posts are designed to be short, informative and thought-provoking. They are not exhaustive, prescriptive or meant to convey a “final say.” I aim to share my personal insights and learnings, highlight topics, areas or nutritional controversies of interest, and perhaps spark some questions or new insight in you.

I aim to publish once a week for the duration of the spring term. The posts will always include references to books or articles I am reading, as well as the latest science-backed research. As for the research, know that I will incorporate meta-analyses and narrative reviews when at all possible. These types of studies reflect the broadest body of research and therefore add a degree of applicability and protection against bias.

I look forward to your comments, welcome your thoughts, and, as always, hope you enjoy!

References

Ferrando, A. A., Wolfe, R. R., Hirsch, K. R., Church, D. D., Kviatkovsky, S. A., Roberts, M. D., Stout, J. R., Gonzalez, D. E., Sowinski, R. J., Kreider, R. B., Kerksick, C. M., Burd, N. A., Pasiakos, S. M., Ormsbee, M. J., Arent, S. M., Arciero, P. J., Campbell, B. I., VanDusseldorp, T. A., Jager, R., Willoughby, D. S., … Antonio, J. (2023). International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance. Journal of the International Society of Sports Nutrition, 20(1), 2263409. https://doi-org.pacificcollege.idm.oclc.org/10.1080/15502783.2023.2263409

Greenfield, B. (2020). Boundless: Upgrade Your Brain, Optimize Your Body & Defy Aging (1st ed.). Victory Belt Publishing.

Momentous. (n.d.). Vital Aminos. https://www.livemomentous.com/products/vital-amino

Salem, A., Trabelsi, K., Jahrami, H., AlRasheed, M. M., Boukhris, O., Puce, L., Bragazzi, N. L., Ammar, A., Glenn, J. M., & Chtourou, H. (2024). Branched-Chain Amino Acids Supplementation and Post-Exercise Recovery: An Overview of Systematic Reviews. Journal of the American Nutrition Association, 43(4), 384–396. https://doi-org.pacificcollege.idm.oclc.org/10.1080/27697061.2023.2297899