Amino acids are referred to as the building blocks of proteins, as these are required for the synthesis of proteins. Branched-chain amino acids (BCAA) are named so, due to their structure. Basically, these are amino acids that have aliphatic side-chains with a branch, which means that a carbon atom is bound to more than two other carbon atoms. These are called essential amino acids, as these cannot be synthesized by the body. These can be synthesized through one's diet. These include essential amino acids called leucine, isoleucine, and valine. It is believed that BCAAs might play a vital role in protein synthesis, and might lower the rate of protein breakdown, thereby facilitating muscle gain. Also, these might lower the serotonin levels, thereby enhancing exercise endurance. Since these are metabolized in the muscle, they get absorbed into the bloodstream quickly. This allows one to perform intensive workouts. BCAAs are needed for the maintenance of muscle tissue, and appear to preserve muscle stores of glycogen (a storage form of carbohydrate that can be converted into energy). However, a study suggests that BCAA supplementation (typically 10-20 grams per day) does not result in meaningful changes in body composition, nor does it improve exercise performance or enhance the effects of physical training. BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat. Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning. BCAAs can activate glutamate dehydrogenase, which is an enzyme that is deficient in people affected by amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease. In one double-blind trial, daily intake of 26 grams of BCAA supplements helped ALS patients maintain muscle strength. However, a larger study was ended early when people using BCAAs not only failed to improve, but experienced higher death rates than the placebo group. Other studies have shown no benefit of BCAA supplementation for ALS or other neuromuscular diseases, though a small group of people affected by diseases of the nervous system collectively called spinocerebellar degeneration did improve when given BCAAs in a preliminary study. A study investigating the advantages of BCAA supplementation in diabetics undergoing an intense exercise program found no additional benefit of BCAAs on reducing abdominal fat or improving glucose metabolism. Individuals affected by liver diseases (hepatic encephalopathy that could lead to coma) have low concentrations of BCAAs, and elevated levels of certain amino acids. Preliminary research suggested that the use of BCAA supplements in people affected by this condition might prove beneficial. Double-blind studies have produced somewhat inconsistent results, but a reanalysis of these studies found an overall benefit for those experiencing the symptoms of encephalopathy. Therapeutic effects of BCAAs have also been shown in children with liver failure and adults with cirrhosis of the liver. People affected by chronic kidney failure may also benefit from BCAA supplementation. A preliminary study found improved breathing and sleep quality in people who were given BCAAs intravenously during kidney dialysis. Phenylketonuria (PKU) is a genetic disease that causes abnormally high amounts of phenylalanine and its end products to accumulate in the blood, which in turn causes damage to the nervous system. A controlled trial demonstrated that the regular use of BCAAs by adolescents and young adults with PKU improved performance on some tests of mental functioning. This outcome makes sense because BCAAs may compete with phenylalanine, thereby reducing its toxic effects. On a concluding note, it's advisable to take BCAA supplements under medical supervision. So, if you are planning to take this supplement for increasing muscle mass or endurance, make sure that you do so after consulting your healthcare provider. Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.