Branched-chain amino acid (BCAAs) are one of the top four most frequently used sports supplements. BCAAs comprise Leucine, Isoleucine and Valine which are 3 of the 9 essential amino acids. There are approximately 20 amino acids but 9 the body can not synthesize so it is important to get them from foods.
How do they work?
To turn on protein synthesis via mTOR pathway “mechanistic target of rapamycin.” You must eat 3-4g of leucine in a meal which equates to 20-30g of a protein meal.
So surely now that you’ve eaten enough leucine and you’ve turned on protein synthesis, this should be enough to continue to build and maintain muscle whilst dieting?
Do they work?
Protein quality of a food is measured by the amino acid score. This is done by measuring the quantity of essential amino acids in a protein source. As BCAAs only contain 3 of the 9 essential amino acids, this makes it an incomplete protein source.
It’s all well and good that it can turn on protein synthesis via leucine but you need a complete protein source to lay down new muscle tissue.
Therefore, we recommend eating a complete protein source (containing all 9 amino acids) such as meat, eggs or whey protein.
For certain people, particularly those following a vegan diet, having Essential amino acids (EAA) is useful to add to incomplete protein sources. These foods (grains, legumes, seeds, nuts etc) are incomplete protein sources so adding EAAS can be useful to make sure you get all 9 essential amino acids in adequate amounts.
What do the studies show?
All the studies now show the BCAAs are ineffective at building and maintaining muscle muscle so they are a complete waste of money. If you are therefore eating complete protein sources then you do not need to supplement with BCAAs.
If your total protein intake is adequate 1.6g-2.2g/kg per day then BCAAs have absolutely no benefit.
These are some studies below that are factual proof.
Plotkin DL, Delcastillo K, Van Every DW, Tipton KD, Aragon AA, Schoenfeld BJ. Isolated Leucine and Branched-Chain Amino Acid Supplementation for Enhancing Muscular Strength and Hypertrophy: A Narrative Review. Int J Sport Nutr Excerc Metab. 2021 May;31(3):292301. PMID: 33741748
Marcon M, Zanella PB. The Effect of Branched-chain amino acids supplementation in physical exercise: A systematic review of human randomized control trials. Sci Sports. Available online 20 January 2022. https//doi.org/10.1016/j.scispo.2021.05.006.
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