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Do You Really Want to Use Branched Chain Amino Acids?

Branched Chain Amino Acids

Nancy Neithercut

BCAA’s What are they? What are the claims?

Branched chain amino acids (BCAA’s) are bits of the building blocks of proteins and include three of the essential amino acids we need to consume in food (our bodies can make non-essential amino acids). They include: leucine, isoleucine, and valine and are found in meat, dairy, and legumes. They are the ‘miracle’ ingredients in concentrated whey and soy protein powders that are supposed to be important for muscle protein synthesis and possibly reduce muscle breakdown. The "Branched-chain" refers to the chemical structure of these amino acids, seen here

BCAAs are also used for reduced brain function in people with advanced liver disease (1) (2), included in a Cochrane review (3), and for a movement disorder often caused by antipsychotic drugs.

Athletes also commonly use them as they think they will improve performance. There is a hypothesis that consumption of these amino acids may prevent or delay central fatigue, reduce muscle breakdown, and other purposes, but there isn't enough reliable information to support these other uses, and one of the side effects is fatigue.

What does the research say?

‘There are no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed. Both of these intravenous infusion studies found that BCAAs decreased muscle protein synthesis as well as protein breakdown, meaning a decrease in muscle protein turnover. The catabolic state in which the rate of muscle protein breakdown exceeded the rate of muscle protein synthesis persisted during BCAA infusion. We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.’ Basically, your body needs pools of amino acids to make proteins, and foods and recycled proteins work best. Isolated amino acids prevent building muscle and prevent the tearing down of muscle mass.

This research shows that taking BCAA’s also prevent amino acid absorption. (4)

A study of intravenous BCAA compare BCAA with glucose, glucose alone or placebo in well trained athletes, bicyclists cycling 100 kilometers, two plus hours. There was no enhance performance or proof that fatigue was reduced or altered. There was more ammonia in the blood with the BCAA group, which concerns me about stress on the kidneys and possible bone deterioration. (5)

However this study shows that taking BCAA’s may reduce heat stress during exercise. (6) We know that acclimatizing to heat and adequate hydration are crucial, and this study does not convince that taking isolated nutrients can make up for training and nutrition including hydration.

There are studies that claim the BCAA hypothesis is true, that taking them effectively reduces the muscle soreness and fatigue sensation, and that the perceived changes could be attributed to the attenuation of muscle damage and inflammation. (7)

There is research showing that that these supplements may make you hungry and depressed because there is an increase in BCAA blood levels, and BCAA takes tryptophan’s position within the brain, which results in reduced synthesis of serotonin, decreasing mood. (8) They may decrease insulin sensitivity and promote obesity. (9)


I would never recommend any isolated supplement. These BCAA’s appear to cause amino acid imbalance and all the problems that accompany trying to fool Mother Nature. Whole foods are always best! There are no short cuts, no magic foods. A well structured whole food plant based diet is best for health and performance. Increased hunger and depression are side effects no one would want!

(1) Long-term oral administration of branched chain amino acids after curative resection of hepatocellular carcinoma: a prospective randomized trial. The San-in Group of Liver Surgery. Br.J Surg. 1997;84(11):1525-1531.

(2) Marchesini, G., Bianchi, G., Merli, M., Amodio, P., Panella, C., Loguercio, C., Rossi, Fanelli F., and Abbiati, R. Nutritional supplementation with branched-chain amino acids in advanced cirrhosis: a double-blind, randomized trial. Gastroenterology 2003;124(7):1792-1801.

(3) Gluud LL, Dam G, Les I, Marchesini G, Borre M, Aagaard NK, Vilstrup H. Branched‐chain amino acids for people with hepatic encephalopathy. Cochrane Database of Systematic Reviews 2017, Issue 5. Art. No.: CD001939. DOI: 10.1002/14651858.CD001939.pub4. Accessed 10 October 2022.

(4) Wolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr. 2017 Aug 22;14:30. doi: 10.1186/s12970-017-0184-9. PMID: 28852372; PMCID: PMC5568273.

(5) Madsen, K., MacLean, D. A., Kiens, B., and Christensen, D. Effects of glucose, glucose plus branched-chain amino acids, or placebo on bike performance over 100 km. J Appl.Physiol 1996;81(6):2644-2650.

(6) Mittleman, K. D., Ricci, M. R., and Bailey, S. P. Branched-chain amino acids prolong exercise during heat stress in men and women. Med Sci Sports Exerc. 1998;30(1):83-91

(7) Matsumoto, K., Koba, T., Hamada, K., Sakurai, M., Higuchi, T., and Miyata, H. Branched-chain amino acid supplementation attenuates muscle soreness, muscle damage and inflammation during an intensive training program. J Sports Med Phys.Fitness 2009;49(4):424-431.

(8) Solon-Biet, S.M., Cogger, V.C., Pulpitel, T. et al. Branched-chain amino acids impact health and lifespan indirectly via amino acid balance and appetite control. Nat Metab 1, 532–545 (2019).

(9) Solon-Biet, S.M., Cogger, V.C., Pulpitel, T. et al. Branched-chain amino acids impact health and lifespan indirectly via amino acid balance and appetite control. Nat Metab 1, 532–545 (2019).

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