Branch Chain Amino Acids


BCAAs are branched chain amino acids. Amino acids are the building blocks of protein. There are 20 different amino acids, and all the structures in our bodies, be that muscle, bone, tendon, hair, skin are all made up of different combinations and amounts of the amino acids.

There are 8 essential amino acids, meaning that we cannot make them and therefore they must be eaten in the diet. This is why it’s important to make sure sufficient protein is taken in the diet, from a variety of sources. High quality or complete proteins will include all 20 amino acids, including the essential ones. High quality protein sources include all animal-based sources, such as meat, fish and dairy, and some plant-based sources such as soya. Some plant sources such as pea are not complete proteins and are not very digestible.


3 of the 8 essential amino acids make up a third of lean muscle mass; these are the branched chain amino acids valine, leucine and isoleucine. This means that for strength athletes looking to build lean muscle or endurance athletes looking to maintain lean muscle mass BCAA intake is very important.

In terms of lean muscle building the stimulus of muscle protein synthesis is also very important. Protein synthesis is stimulated when protein is ingested, and is broken down during exercise. This means it is crucial that protein is ingested around exercise in order to support the rate of muscle protein synthesis.  As well as a major building block the BCAA leucineacts as a further stimulusto muscle protein synthesis, so again it’s inclusion around exercise is crucial.

For endurance exercisers when energy (particularly carbohydrate) availability is low, protein can be oxidised to produce energy. This is common during long endurance events, particularly if carbohydrate fuelling levels are not maintained. The BCAAs are the most readily oxidised out all 20 amino acids, making lean muscle mass particularly susceptible to these anabolic losses. Of course this is not ideal as it is lean muscle that is needed to perform muscle contractions to produce force and drive them forwards