Branched Chain Amino Acids (BCAA)

Professor Jo-Anne Murray
PhD, MSc, PgDip, BSc (Hons), BHSII, RNutr, PFHEA University of Glasgow Veterinary School

What are branched chain amino acids?

Amino acids are individual units that combine to make up proteins. There are 22 amino acids that are structured in different ways to make proteins of different sizes and shapes and with a variety of functions. Some amino acids are made in the body while others are not. Those that are not are known as essential amino acids as these need to be supplied in your horse’s diet. If these essential amino acids are not provided this means that certain proteins cannot be formed. Branched Chain Amino Acids, also known as BCAA, are a group of three essential amino acids: leucine, isoleucine and valine. These are known as branched chain amino acids due to their structure, which has a chain that branches off to one side.

Why are branched chain amino acids important?

BCAAs comprise around 35 percent of the essential amino acids found in muscle proteins. They have been shown to be important in building muscles, decreasing muscle fatigue and alleviating muscle soreness.

BCAA and muscle development

Your horse’s body contains a large amount of muscle, which makes up between 40 and 55 percent of their total body weight. Muscle itself contains around 70 percent water, 20 percent protein and 10 percent fat, glycogen, vitamins and minerals. However, proteins make up the majority of solid skeletal muscles and therefore are of particular interest in performance horses.

It takes time and effort to build muscle in your horse and understanding the factors that help a horse to build or lose muscle can be of great benefit in training. Muscle mass is determined by protein synthesis and breakdown (also known as protein turnover) and this happens simultaneously. BCAAs comprise around 35 percent of the essential amino acids found in muscle proteins. Amino acids must be present in adequate amounts for this to take place. Leucine, which is one of the BCAAs, is reported to be particularly important for muscle protein synthesis. In humans, BCAA have been shown to activate the enzymes that are responsible for building muscle. Studies in other animals have also shown that isoleucine (another BCAA) supplementation induces glucose uptake into cells and increases muscle growth.

During exercise there is an increase in muscle protein turn over, which means that the body breaks down the protein and then re-synthesises it. This process is an important cycle of events for building muscle and therefore the greater protein turnover results in increased muscle mass. There are a number of factors that affect muscle mass including; age, health status, hormones, medications, level of physical activity, and nutrition. However, BCAA supplementation appears to be beneficial in supporting muscle development.

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