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BCAAs: what they are, what they are used for and what the acronyms 8:1:1, 4:1:1 and 2:1:1 mean
BCAAs: what they are, what they are used for and what the acronyms 8:1:1, 4:1:1 and 2:1:1 mean

BCAAs: what they are, what they are used for and what the acronyms 8:1:1, 4:1:1 and 2:1:1 mean

Date: August 18, 2022

BCAA, what is it about?

Branched-chain Amino Acids are three alpha amino acids called Leucine, Isoleucine and Valine. Like the other alpha amino acids, also leucine, isoleucine and valine are made up of an amino group (-NH2), a carboxylic group (COOH) and a side chain on the carbon in alpha, i.e. of the carbon atom immediately adjacent to the carbon of the carboxylic group, from which they take the name of alpha amino acids.

Each alpha amino acid has a characteristic side chain which gives it part of its chemical-physical characteristics. The fact that these three alpha amino acids are called "branched” is due precisely to the particular structure of the side chains which, when represented through the structural formulas used in chemistry to study molecules, look like branches that branch out from the alpha carbon of the amino acid.

Leucine, isoleucine and valine are part of the 9 alpha amino acids that are defined as essential, as they are not synthesized by the human body and must be introduced with the diet. The content of BCAAs in foods is generally related to the total protein content of the same, and these represent on average 50% of the essential amino acids and 20% of the total amino acids that derive from the diet. The ratio of the three BCAAs found in protein-rich foods has been identified as 1.6: 2.2: 1 where valine, leucine and isoleucine are the amino acids indicated (therefore in the ratio 1.6 valine: 2.2 leucine: 1 isoleucine).

What are branched chain amino acids used for?

Branched chain amino acids have 3 main functions: they are used for protein synthesis where, together with the other 17 alpha amino acids, they are the constituent "blocks" of Protein, they are used for energy purposes and act as signal molecules. Another factor that unites these 3 amino acids is that they are not metabolized in the liver, but directly in the muscle tissue. The first stage of BCAA metabolism is shared and takes place by the BCAT enzyme of which there are 2 isoforms, one cytosolic (BCAT1) and one mitochondrial (BCAT2). This first reaction, called transamination, is of the reversible type and leads to the obtaining of BCKAs or branched-chain alpha-ketoacids, an intermediate. The second step is the reaction catalyzed by the BCKDH enzyme, located on the inner membrane of the mitochondria and, unlike the first reaction, it is irreversible. The products obtained from this second reaction will undergo further chemical reactions that will lead to the production of more products, including the intermediates of the Krebs cycle, used by the cell to produce energy.

An example of the ability of BCAAs to act as signal molecules is represented by the bond that leucine is able to establish with Sestrin2, a protein encoded by the SESN2 gene. This protein in the absence of leucine binds and inhibits GATOR2, an inhibitor of the activity of the factor mTORC1, which in turn is a promoter of protein synthesis. Therefore, thanks to the binding of leucine with the Sestrin2 protein, the GATOR2 complex can positively regulate mTORC1 and consequently promote protein synthesis.

What do 2:1:1, 4:1:1, and 8:1:1 mean?

In the sports world, branched chain amino acids are certainly one of the best known and most used supplements: from bodybuilding to fitness, it is unlikely that a "gym goer" has not heard of or even made use of this type of supplement.

Several formulations of BCAAs are available on the market, which differ in the amount of leucine. This difference is easily identifiable by observing the 2: 1: 1, 4: 1: 1 and 8: 1: 1 symbols, visible on the packaging containing the amino acid supplement.

This abbreviation represents the ratio of the three branched amino acids in the supplement: Valine - Isoleucine - Leucine. If a 2: 1: 1 ratio is indicated, the amount of leucine will be equal to 2 times that of isoleucine and valine. Similarly, if the abbreviation indicated is 8: 1: 1, the amount of leucine will be 8 times that of isoleucine and valine. The reason for the presence on the market of this type of formulations lies in the fact that, as previously mentioned, leucine is able to promote protein synthesis.

The importance of Leucine for protein synthesis has been verified by several scientific studies, which have confirmed that this BCAA is able to elevate and prolong protein synthesis, helping to create an anabolic environment immediately after a workout by activating the pathway. cell signaling mTORC1 (also mentioned above).

So… which ones to choose?

The answer to this question is not the most obvious. In fact, it is necessary to take into account many variables, and in many cases the motivation for using the supplement. We will try to leave you some advice below that can help you in your choice.

BCAA 2: 1: 1 - Mainly they have an energy support function during long and intense workouts and muscle recovery. Therefore suitable for pre and post-workout.

BCAA 4: 1: 1 - Reduction of fatigue, support to increased energy demands and recovery: these are the main benefits deriving from the intake of this type of BCAA. Ok, then, in the intra and post-workout.

BCAA 8: 1: 1 - At the end of training do we need to recover to the maximum? The high amount of leucine supports this process while satisfying the energy demands that occur at the end of the workout.


BCAAs are, as we have already said, among the most widely used supplements in the world of fitness. There is a lot of evidence to support their use: in addition to the plastic purpose (of muscle building and support), they also have a role in the production of energy during muscular effort and in recovery. The choice of type and quantity to be taken are obviously strictly personal, and may vary on the basis of individual needs.


  1. Neinast M, Murashige D, Arany Z. Branched Chain Amino Acids. Annu Rev Physiol. 2019;81:139-164. doi:10.1146/annurev-physiol-020518-114455
  2. Kamei Y, Hatazawa Y, Uchitomi R, Yoshimura R, Miura S. Regulation of Skeletal Muscle Function by Amino Acids. Nutrients. 2020;12(1):261. Published 2020 Jan 19. doi:10.3390/nu12010261
  3. Branched-Chain Amino Acid Metabolism E. Harper, R. H. Miller, K. P. Block Annual Review of Nutrition 1984 4:1, 409-454
  4. Brestenský, Matej & Nitrayová, S. & Patras, Peter & Heger, Jaroslav & Nitray, Jozef. (2015). Branched chain amino acids and their importance in nutrition. Journal of Microbiology Biotechnology and Food Sciences. 5. 197-202. 10.15414/jmbfs.2015.5.2.197-202.

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