BCAA is a triad of branched chain amino acids, leucine, isoleucine and valine. The three amino acids are called essential, because the body is unable to synthesize them endogenously thus it is necessary to obtain them from dietary sources.

   Natural sources of BCAA’s are mainly animal protein foods such as meat and dairy products, while good plant sources are legumes. Compared with other amino acids, BCAA are not metabolized in liver, but directly in muscle tissue. Due to their cell metabolism, it is believed that BCAA may improve athletic performance, particularly in pursuit of moderate-high intensity exersise, influencing mainly the fatigue in central nervous system.

   BCAA’s are hydrophobic molecules which are the energy substrate of muscle cells, particularly in situations of increased energy requirements.  They are the building block of muscle fibers (~ 35%) and are involved in energy production and in gluconeogenesis in liver. During prolonged exercise BCAA, which are the third source of energy in muscle cells after carbohydrates and fat, are mostly catabolized. When exercise intensity and duration is high, the cellular storage of BCAA is depleted, leading to increased uptake of tryptophan by brain cells. This increase leads to serotonin synthesis in brain and thus there is a central fatigue. Fatigue is the biggest stumbling block in the performance of athletes and trainees. Studies have shown that BCAA supplementation before and after exercise resulted in reduced fatigue and improved athletic performance. BCAA catabolism was lower when during exercise was consumed carbohydrates.

   Because branched amino acids play an important role in building muscle tissue, it was considered that their ingestion before and after exercise will help to decrease muscle catabolism and to increase muscle protein synthesis. Because of the involvement of branched amino acids in protein synthesis, it became apparent and the role of BCAA in immunization. There is evidence that support that BCAA supplementation helps in strengthening the immune system because they involved in the production protein molecules, DNA and RNA of lymphocytes.

   The concentration of BCAA’s is abundant in protein foods. The supplement intake of BCAA should happen with empty stomach. Daily intake of 10-30gr. appears to have no negative health effects.



  • Negro, Massimo, et al. “Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system.”  Journal of Sports Medicine and Physical Fitness  48.3 (2008): 347.
  • Shimomura, Yoshiharu, et al. “Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise.”  The Journal of nutrition  134.6 (2004): 1583S-1587S.
  • Ohtani, Masaru, Masaaki Sugita, and Kimiaki Maruyama. “Amino acid mixture improves training efficiency in athletes.”  The Journal of nutrition  136.2 (2006): 538S-543S.