BCAAs are heavily marketed as a worthy supplement to your active lifestyle but do they really offer any gains?
What are BCAAs?
There are 20 amino acids that the human body uses to make proteins (protein is a chain of amino acids). Eleven of the amino acids can be made by our bodies using other amino acids from our diet. Nine of them cannot be synthesized and for this reason they are called “essential amino acids.”
- The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
The branched chain amino acids are leucine, isoleucine, and valine. The “branched chain” designation refers to their chemical structure where they have two carbons “branching” from one, unlike the others.
Why are BCAAs important?
Amino acids are used in three ways in the body: 1) Incorporated as proteins into body tissues and muscle, 2) as fuel, and 3) as a signal.
BCAAs are particularly highly active in these three ways when it comes to building muscle tissue.
- Leucine, isoleucine, and valine (the 3 BCAAs) make up 1/3 of muscle protein (Mero, 1999).
- BCAAs are used more than others as fuel, broken down for their carbon atoms and then used to make structures that help make ATP which the body uses as energy (Layman, 2002).All three BCAAs, leucine in particular, are used heavily by the body for energy in both aerobic endurance exercise and in skeletal muscle protein synthesis. Interestingly, they are used less so in anaerobic HIIT type exercise. (Mero, 1999)
- Leucine in particular is used in the insulin signaling cascade. Insulin is a highly anabolic hormone, meaning it signals the body to start repairing and building tissue once carbohydrates are eaten after exercise. It’s long been known that insulin is released when the body eats carbohydrates. As it turns out, consuming leucine (even without carbs) also causes insulin to be released (Layman, 2002).
Do I need to take BCAAs as a supplement?
As BCAAs are so highly concentrated in muscle tissue, they are abundant in diets that include meat sources of protein. Leucine in particular is also found in high amounts in dairy and even more so in whey protein.
The current US official Recommended Dietary Allowance of leucine is 14mg/kg/day for adults (RDA, 1989). However, many sources, such as Mero, 1999 and the American College of Sports Medicine (2015) recommend a minimum leucine intake of 45mg/kg/day with a much higher intake recommended for athletes. This comes out to about 3-5g of leucine per day.
In a typical omnivorous diet, if you eat 1 gram protein per 1 kg of body weight (or roughly 0.5 gram of protein per 1 lb of body weight) per day, you are getting enough BCAAs. In this case, you probably don’t need to supplement BCAAs.
While no plant source of protein is as high in leucine as dairy, many plant proteins do contain adequate amounts of leucine and BCAAs. Pea protein is particularly low in leucine but soy protein and wheat protein (particularly vital wheat gluten) are both relatively high in leucine. Legumes (like kindey beans, black beans, pinto beans) are somewhere in the middle.
If you are following a primarily plant-based diet, you may consider taking BCAAs as a supplement to ensure you are consuming enough to maximize your gains from the hard work you put in at the gym. However, if you consume at least half your protein from soy, wheat, and legumes proteins, you are still likely getting enough and don’t need to supplement.
What does the research show?
Interestingly, BCAAs have been extensively studied in athletes and show no statistically significant benefits to endurance, strength, or performance (Mero, 1999).
Despite the high amount of BCAAs being used for energy during training, taking extra doesn’t seem to help.
None of the studies I have come across have studied BCAA supplementation in athletes consuming a plant-based diet though. Additionally, none of the studies look into BCAA supplements in diets that likely don’t contain enough protein at baseline.
Do I, Dr. Elle, supplement BCAAs?
I actually do like to take BCAAs. Really, it’s mostly just because I enjoy it. I actually really like the BCAA drink powders that are available. I think they taste much better than sugary koolaid or other drink mixes and for an extra 5g of protein, hell yeah!
While it’s not my primary reason, I do feel there may be some minor benefit.
While I do eat occasional meat and dairy, I like to prioritize fish and plant-based protein sources. It’s difficult to get enough total protein (1g/lb) in my diet every day using these whole food sources alone. Taking BCAAs give me a bit of reassurance that I’m getting enough of the most important amino acids (especially leucine) in my diet every day.
Common Myth: Do BCAAs have calories?
YES. There is a very odd restriction from the FDA that states manufacturers cannot report supplements containing protein in the form of individual amino acids (FDA, 2005). Who decided to make that restriction and why makes no sense at all. It’s an old law that hasn’t been updated and was likely created without foreseeing this being an issue.
According to May & Hill (1990), leucine, isoleucine, and valine all have about 4.6kcal/g.
So BCAA powder that contains 10g of BCAAs has 46 calories worth of protein.
As stated above, leucine is directly involved in the insulin cascade and causes insulin to be released. Many other amino acids and proteins have a similar but more minor effect. So if you are following an intermittent fasting plan, BCAAs will indeed break your fast.
BCAAs include leucine, isoleucine, and valine and are heavily involved both during high intensity training and post-workout in muscle growth. You most likely get plenty of BCAAs in your daily omnivorous diet but there may be reasons to supplement, particularly if you follow a primarily plant-based diet and as a better alternative to high-sugar drinks.
- American College of Sports Medicine. Protein Intake for Optimal Muscle Maintenance. 2015.
- Crowe, M. J., Weatherson, J. N., & Bowden, B. F. (2006). Effects of dietary leucine supplementation on exercise performance. European journal of applied physiology, 97(6), 664-672.
- Food and Drug Administration; “Dietary Supplement Labeling Guide: Chapter IV. Nutrition Labeling”; April 2005; https://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/dietarysupplements/ucm070597.htm
- Goldberg A. L. & Odessey R. (1972). Oxidation of amino acids by diaphragms from fed and fasted rats. Am J Physiol; 223: 1384-91
- Layman D. K. (2002). Role of leucine in protein metabolism during exercise and recovery. Canadian journal of applied physiology = Revue canadienne de physiologie appliquee, 27(6), 646–663. https://doi.org/10.1139/h02-038
- May, M. E. & Hill J. O. (1990). Energy content of diets of variable amino acid composition. The American Journal of Clinical Nutrition. 52(5) 770–776 https://doi.org/10.1093/ajcn/52.5.770
- Mero, A. (1999). Leucine supplementation and intensive training. Sports Medicine, 27(6), 347-358.
- Nissen, S., Sharp, R., Ray, M., Rathmacher, J. A., Rice, D., Fuller, J. C., Jr, Connelly, A. S., & Abumrad, N. (1996). Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training. Journal of applied physiology (Bethesda, Md. : 1985), 81(5), 2095–2104. https://doi.org/10.1152/jappl.19188.8.131.525
- Recommended Dietary Allowances: 10th Edition (1989). Protein and Amino Acids. In: National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Washington, DC: National Academies Press (US).