It is important that all of us get enough branched chain amino acids (BCAA) but even more so for those who are professional athletes and those who exercise on a regular basis.  The essential BCAA amino acids include leucine, isoleucine and valine.  These three amino acids contain at least one side chain methyl group making them branched.  These essentials are actually metabolized in skeletal muscle as opposed to liver.  Remember, liver metabolizes most molecules.  Amino acids are generally used to make proteins or broken down to make energy.  So, why would BCAA be important for athletes?  Athletes use their amino acids to make protein which is muscle building and important for advanced performance.  Studies indicate that if the athlete’s diet is high in the essential BCAAs then they will be in good shape.  With an improper diet, performance is greatly hindered.  Supplementation of BCAA may be required.  High levels of BCAAs have also been demonstrated to decrease fatigue in anaerobic as well as endurance activities.  Of the three essential branched chain amino acids, leucine has been found to be the most important BCAA due to its anti-catabolic ability and the part it plays in protein synthesis. 

Large amounts of leucine in the diet actually stimulates protein synthesis in skeletal muscle as well as burn body fat.  It is also reported that physical exercise tends to damage muscle fiber cells which in turn stimulates satellite cells to come together as well as fuse with muscle fiber cells.  These satellite cells are actually stem cells found within the muscle tissue.  They have the ability to fuse to muscle cells and cause them to hypertrophy (grow or get larger as well as repair).  Leucine does this by enhancing mTor signaling in muscle.  The mammalian target of rapamycin (mTor) activation is required for skeletal muscle hypertrophy.  Mtor, although not well understood at this time,  is responsible for protein synthesis because it is believed to inhibit an initiation factor that is responsible for repression of translation of muscle protein and it is also believed to activate ribosome biogenesis by modulating the activity of the kinase that phosphorylates the 70kDa ribosomal subunit which in turn is important for translation of ribosomal proteins and expression of ribosomal RNA. 

Interestingly, BCAAs escape certain modifications that other amino acids receive.  This has to do with the fact that the liver doesn’t have a branched chain aminotransferase enzyme.  What that means is that leucine, isoleucine and valine essentially enter the blood as is meaning that the amount you ingested will be the same amount that is found in blood.  This means that the amount you consume will essentially be at the same concentration in skeletal muscle.

Studies demonstrate that making use of diets that are higher in protein and lower in carbohydrates enhance weight loss with increased loss of body fat with reduced loss of lean body mass.  In other words  high protein diets spare muscle protein loss and at the same time enhance sugar control.  It is believed that leucine interacts with the insulin-signaling pathway by way of protein synthesis resulting in sparing of muscle protein during limited energy intake during exercise.  During exercise glucose is recycled maintaining proper levels of glucose maintaining low insulin responses.  High levels of leucine inhibit aerobic respiration such that skeletal muscle uses glucose directly from blood or glycogen stores while increasing the rate of gluconeogenesis.         

Athletes have been aware of BCAAs for some time and have supplemented their diets to improve performance and prevent muscle deterioration during heavy exercise.  Some people use BCAAs to stave off fatigue and improve concentration when they need to pay attention to detail whether during study or presentations.  Clinically, BCAAs have been used on individuals with chronic liver disease that have loss of brain function such as spinocerebellar degeneration, amyotrophic lateral sclerosis, or muscular dystrophy as well as patients who have certain kidney diseases.

Why You Should Take Branched Chain Amino Acids

Branched chain amino acids (BCAA) are important for protein synthesis.  This is true for every cell in the body but particularly important for skeletal muscle not only for growth but repair as well.  You may not get enough BCAAs depending on your diet or if you exercise heavily.  Clinical studies have reported that  higher levels of BCAAs in the diet enhance skeletal muscle recovery and growth.  Skeletal muscle hypertrophy is a direct result of taking in high levels of BCAAs and in particular leucine.  If you are interested in losing body fat while maintaining lean muscle, a diet high in protein preferably foods rich in BCAAs and low in carbohydrates is for you.  If you want to improve brain function, the benefits of BCAAs are far reaching.  Many neurotransmitters in the brain are amino acids or amino acid derivatives.  If you are concerned about maintaining a healthy cardiovascular system, BCAAs maintain healthy heart muscle.  If you’re interested in maintaining a healthy immune system, consider taking in more BCAAs.  BCAAs  boost the immune system and will help to reduce inflammation.  As you can see, the benefits of BCAAs are important for athletes and individuals who have chronic liver and kidney disease.


Ohtani M, Sugita M, Maruyama K. Amino acid mixture improves training efficiency in athletes. J Nutr. 2006 Feb; 136(2): 538S-543S.

Kraemer WJ, Ratamess NA, Volek JS, Hakkinen K, Rubin MR, French DN, Gomez AL, McGuigan MR, Scheett TP, Newton RU, Spiering BA, Izquierdo M, Dioguardi FS. The effects of amino acid supplementation on hormonal responses to resistance training overreaching. Metabolism. 2006 Mar; 55(3): 282-91.  (all about BCAAs)