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Protein is one of the most discussed topics in sports nutrition. This is probably because it’s the second-most abundant molecule in fat-free bodily tissues (water being the most abundant). It plays a pivotal role in exercise recovery and it is involved in nearly all bodily functions and processes.

Proteins are responsible for many functions throughout the body, including acid–base balance (the process of achieving, or the state of, equilibrium between acidic and alkaline molecules), energy production, cell signaling (the process of communication between cells by biological messengers to govern cellular function), and nutrient transport. For these reasons and many more, protein is an essential dietary nutrient for healthy living.

We’ve all seen BCAAs (Branched Chain Amino Acids) and EAAs (Essential Amino Acids) being sold by our favourite sports nutrition/supplement companies - but which is ‘better’? A better question to ask might be: which purpose do they both best serve?

To have this discussion we need to look a little broader first:

Amino Acids

All proteins are made up of amino acids. There are hundreds of amino acids in nature, but there are just 20 amino acids that the human body needs to perform its various functions.

Amino acid structure and arrangement has five main blocks: a central carbon, a carboxyl group (organic acid – COOH), a hydrogen, an amino group (NH2), and a side chain (R group). The side chain is what makes each individual amino acid unique. The side chain is different between every amino acid. For example, glycine only has a single hydrogen in the side-chain position, while leucine’s side chain is a more complex carbon and hydrogen structure (Figure 1).

Fig 1: The structure of amino acids

Essential Amino Acids

EAAs are amino acids that are necessary for bodily functions but can’t be synthesized by the body and, therefore, must be obtained in the diet. EAAs must be consumed in our diets through food or supplementation because they are necessary for bodily functions and cannot be synthesized in the body.

There are nine EAAs, which include three BCAAs (the three essential amino acids [leucine, isoleucine, and valine] which are abundant in skeletal muscle tissue and named for their branch-like structure).

There are also six conditionally essential amino acids. Unlike EAAs, conditionally essential amino acids are considered nonessential under normal circumstances and can be synthesized in the body; however, under certain physiological conditions, requirements can outweigh their availability or rate of synthesis, making them essential for some individuals. When this happens, the conditionally essential amino acids have to be obtained through diet. Healthy adults typically don’t need to be concerned about consuming enough conditionally essential amino acids as they only become essential during infancy, injury, disease, or trauma. Nonessential amino acids can be synthesized in the body from other amino acids, typically the EAAs, so they don’t need to be consumed through diet.

With this in mind - if the primary goal is to maximize recovery and facilitate optimal muscle growth, Essential Amino Acids will give the most ‘bang for your buck’ in that the majority of the 20 amino acids can be formed in the body, provided there is a sufficient supply of the 9 essential amino acids.

When supplementing with BCAAs it’s worth considering your main goal. Are you trying to maximize muscle protein synthesis? Do you want some sugar free squash? BCAA’s serve the purpose of supplying leucine - a vital amino acid in signaling/triggering muscle protein synthesis. Leucine in isolation will not build muscle, but supplementing leucine into an otherwise high-protein diet can help enhance muscle hypertrophy. However, BCAAs don’t supply the full amino acid profile required for muscle protein synthesis to occur, at least not optimally. Another essential amino acid may become a limiting factor to this process and hinder it. This could be avoided by supplementing with EAAs instead and providing your body with a more appropriate amino acid profile for your goals.

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