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Why do I need branched-chain amino acids?

Leucine, isoleucine and valine are the three branched-chain amino acids. These 3 BCAAs are also essential amino acids, meaning they cannot be made by the body and must be obtained from dietary sources. BCAAs are unique as they can be metabolised by the skeletal muscle, while the other essential amino acids are metabolised in the liver.

BCAAs have been commonly used in body building communities for years, but now they are gaining popularity with other athletes and the general active population.

BCAAs have been suggested to be beneficial by:

  • Stimulating muscle protein synthesis (through leucine)
  • Preventing muscle protein breakdown
  • Reducing markers of exercise induced muscle damage and so reducing muscle soreness
  • May have the potential of acting as a fuel source for muscles during exercise
  • May reduce fatigue by interfering with tryptophan transport to the brain and reducing serotonin.

However, studies have shown that they do not always correlate with improved performance and the evidence for the above benefits is only low to moderate at this stage.

The evidence is not conclusive whether BCAA supplementation is superior to whole protein supplementation or carbohydrate intake. Athletes with a tight energy budget may benefit as they may help to build muscle without a large kilojoule load.

For the best effect, BCAA supplementation should be used in amount to provide 2-3g leucine and so far, no negative or toxic effects have been found.

However, It is important to keep in mind that many protein sources contain BCAAs such as meat and eggs and those already consuming adequate protein may not need supplementation.

When considering any supplementation, it is important to consider what is right for you as an individual and consult an Accredited Sports Dietitian or Accredited Practising Dietitian if you’d like more information and guidance of safe and effective supplementation.

References
Foure, A., Bendahan, D. (2017). Is Branched-Chain Amino Acids Supplementation an Efficient Nutritional Strategy to Alleviate Skeletal Muscle Damage? A Systematic Review, Nutrients, 21, 9(10).
Cheng, I.S., Way, Y.W., Chen, I.F., Hsu, G.S., Hsueh C.F. et al. (2016) The Supplementation of Branched-Chain Amino Acids, Arginine, and Citrulline Improves Endurance Exercise Performance in Two Consecutive Days, Sport Sci Med, 5,15 (3), 509-515.
Ferreria, M.P., Li, R., Cooke, M., Kredier, R.B., Willoughby, D.S. (2014) Periexercise coingestion of branched-chain amino acids and carbohydrate in men does not preferentially augment resistance exercise-induced increases in phosphatidylinositol 3 kinase/protein kinase B-mammalian target of rapamycin pathway markers indicative of muscle protein synthesis. Nutr Res, 34 (3), 191-198.
Kephart, W.C., Mumford, P.W., McCloskey, A.E., Holland, A.M., Shake, J.J., et al. Post-exercise branched chain amino acid supplementation does not affect recovery markers following three consecutive high intensity resistance training bouts compared to carbohydrate supplementation, J Int Soc Sport Nutr, 26, 13, 30.