Branched chain amino acids, or BCAAs, have existed in the bodybuilding community since the Eighties. More recently their uses extend beyond bulking up, with benefits in endurance, functional and recreational fitness.
What is an amino acid?
Amino acids are small compounds that act as the building blocks of all protein. Amino acids are named so because of their chemical structure which, contains an amino group and an acidic carboxyl group.
There are about 20 amino acids, of which nine are considered essential, meaning that our body cannot synthesise them so they must be consumed through foods in our diet1.
What are BCAAs?
Isoleucine, leucine and valine are three of the nine essential amino acids. The trio is commonly known as Branched Chain Amino Acids (BCAAs) because of a branched side-chain within their chemical structure.
BCAAs have multiple functions within the human body2:
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BCAAs make up about 40% of essential aminos found in our body
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BCAAs are catabolised to be utilised in the TCA cycle for energy production
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Leucine plays a role in fatty acid and lipid metabolism
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BCAAs assist glucose uptake and its transportation within the body (glucose homeostasis)
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BCAAs are involved in signalling pathways of protein synthesis (muscle growth)
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BCAAs are metabolised in skeletal muscle and so they decline during exercise
What are the benefits of BCAAs?
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Reduced muscle pain (DOMS) and muscle damage
Most of us have experienced pain and stiffness from exercise. It can often be used as an excuse for not going to the gym, just to avoid the dreaded DOMS (Delayed Onset Muscle Soreness). A systematic review of scientific studies showed that BCAA supplementation had a positive effect on reducing exercise-induced muscle damage. The results were seen when BCAAs were supplemented for at least 10 days and consumed prior to the damaging exercise2.
An American study showed that BCAA supplementation prior to and during a long distance endurance event helped to reduce muscle damage from exercise3. This study was conducted on non-elite men showing BCAA relevance in the general fitness community.
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Prevent muscle breakdown whilst shredding fat
Many people who go to the gym are looking to lose weight. It’s common knowledge that exercise and a healthy diet are two of the main factors involved in weight loss. If you have reduced the energy or caloric intake in your diet then, in theory, your body will utilise its stored energy to fuel your workout, and you definitely do not want to go catabolic, where your body breaks down muscle for fuel. Supplementing with BCAAs can assist with maintaining your lean muscle mass and protect your sporting performance whilst exercising4.
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Support mental performance
‘Your mind will quit a thousand times before your body will’ is a saying I personally latch on to during a gruelling workout. People are often surprised by their own strength and fitness abilities when they achieve a goal they originally thought impossible. There is preliminary evidence to suggest that BCAA supplementation can influence perceived exertion and mental performance during exercise5.
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Improve nutritional biomarkers in disease
BCAA supplementation is not only popular in the fitness industry, their use in the medical management of liver disease dates back to the 1970s6. In the body, BCAAs detoxify ammonia in the skeletal muscle and act as an essential substrate for the synthesis of body proteins7. In the progression of chronic liver disease, glycogen stores decrease due to a catabolic state that requires a higher protein intake than usual. Long-term oral BCAA supplementation has proven beneficial effects in patients with advanced liver cirrhosis.
What is the recommended dosage?
Much of the research regarding BCAA supplementation and muscle growth highlights the importance of leucine. However, all three BCAAs need to be consumed together for effective absorption and utilisation within the body.
When supplementing with BCAAs, aim for a 3g dosage of leucine as recommended by Sports Dietitians Australia (2-3g per serving) and several studies (2-5g per serving).
Take home message
Leucine, isoleucine and valine are three of the nine essential amino acids that are known as Branched Chain Amino Acids (BCAAs).
BCAAs have many roles in the human body and supplementation may assist with the dreaded DOMS pain and muscle damage associated with exercise. BCAAs help to protect your lean muscle mass when training and following a low-energy/calorie diet for weight loss. BCAAs may also have a role in central fatigue, where perceived exertion is reduced with supplementation.
References:
- National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Recommended Dietary Allowances: 10th Edition. Washington (DC): National Academies Press (US); 1989. 6, Protein and Amino Acids. Available from: https://www.ncbi.nlm.nih.gov/books/NBK234922/
- Fouré A, Bendahan D. Is Branched-Chain Amino Acids Supplementation an Efficient Nutritional Strategy to Alleviate Skeletal Muscle Damage? A Systematic Review. Nutrients. 2017;9(10):1047. doi:10.3390/nu9101047.
- Kjerulf Greer, B., Woodard, J. L., White, J. P., Arguello, E. M. and Haymes, E. M. Branched-Chain Amino Acid Supplementation and Indicators of Muscle Damage After Exercise. International Journal of Sports Nutrition and Exercise Metabolism. 2007,17, 595-607.
- Dudgeon, W. D, Kelley, E. P. and Scheett, T. P. In a single-blind, matched group design: branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet. Journal of the International Society of Sports Nutrition. 2016, 13:1 https://doi.org/10.1186/s12970-015-0112-9
- Meeusen, R. and Decroix, L. Scholarly Review: Nutritional Supplements and the Brain. IJSNEM. March 2018, vol. 28, issue 2, 200-211 doi: 10.1123/ijsnem.2017-0314
- Fischer JE, Rosen HM, Ebeid AM, James JH, Keane JM, Soeters PB. The effect of normalization of plasma amino acids on hepatic encephalopathy in man. Surgery. 1976;80:77–91.
- Park JG, Tak WY, Park SY, et al. Effects of branched-chain amino acids (BCAAs) on the progression of advanced liver disease: A Korean nationwide, multicenter, retrospective, observational, cohort study. Mubarak. M, ed. Medicine. 2017;96(24):e6580. doi:10.1097/MD.0000000000006580.
