Branched Chain Amino Acids

When you type Branch Chain Amino Acids (BCAA) into a search engine, immediately a number of different brands of supplements pop up suggesting their benefits, mainly to the weight training athletes with their immediate claims being that they:

·         Maintain lean tissue
·         Preserve stores of glycogen
·         Prevent tissue breakdown during training

What are BCAA?

Amino Acids are known as the building blocks for skeletal muscles, enzymes, hormones and other proteins which are necessary for the optimum functioning of the body. Of these amino acids there are both essential and non-essential, with essential amino acids being those which must be ingested by the body through the diet. There are eight known amino acids which can be found in dairy, poultry, eggs, beef and pork, and soy protein for a vegetarian source. The essential amino acids valine, leucine and isoleucine are known as BCAA’s and are thought to be metabolized differently to other amino acids by being taken up by the skeletal muscle rather than the liver to contribute to the energy production, this means they can be quickly depleted.

There are many thoughts as to how BCAA’s within the diet or supplementation can help towards athletic performance the main theory is through Central Fatigue.

Central Fatigue Theory- Prolonged exercise lowers BCAA plasma concentration through oxidation of the amino acids with an increase in plasma free fatty acid concentration from fat oxidation. This creates a cascade effect which ultimately leads to an increase in free tryptophan levels in the brain which can be converted into serotonin. Serotonin can have a negative effect on mood and therefore compromise athletic performance through the feeling of fatigue.

There are two theories in which this can happen:

• During the latter stages of prolonged exercise when there is low blood sugar- this stimulates the body to find glucose from non-carbohydrate sources and BCAA are broken down and used as a fuel source. This creates a reduction BCAA/Tryptophan ratio leaving a higher level of tryptophan to enter the brain and convert to serotonin.

• FFA’s are broken down in higher amounts as glycogen depletion and fat oxidation increases. This creates more competition between Tryptophan and FFA’s to free albumin site and can therefore increase the amount of free tryptophan to cross the blood-brain barrier which can be converted to serotonin.

Other benefits include:

Immune Response- May improve serum glutamine levels leading to a lesser incidence of illness following exercise.

Overtraining- During a period of overtraining glutamine stores can be depleted faster than the body can replenish them and therefore over trained athletes typically suffer from low glutamine levels and BCAA could as above help to improve serum glutamine levels. 

It is thought that by supplementing BCAA in the diet, there will be a higher level of BCAA in the blood during prolonged exercise and decrease the amount of serotonin being produced and resulting in less central fatigue.

But does it really work?

The research is still conflicting on the issue of BCAA and the increase aerobic performances however BCAA’s are as mentioned earlier are essential amino acids and should be consumed within the diet. Although there will be a number of supplements claiming to increase BCAA and athletic performance as with all nutrients, the best sources are those that are natural and choosing a wide variety of food types will ensure a good intake of BCAA's as well as  a wide variety of other nutrients as well. 

The best sources will be protein rich foods, and are normally consumed in sufficient quantities in the regular diet and include, lean red meat, poultry, eggs, dairy including milk, cottage cheese and yoghurts. Non-meat sources include soy protein, brown rice, beans, nuts and lentils.