Branched-chain Amino Acids Peripheral muscle proteolysis, as occurs in cancer cachexia, works to metabolize amino acids required for the synthesis of liver and tumor protein. The administration of amino acids may theoretically serve as a protein-sparing metabolic fuel by providing substrate for both muscle metabolism and gluconeogenesis.88 Branched-chain amino acids (BCAA: leucine, isoleucine, and valine) have been used with the aim of improving nitrogen balance, particularly muscle protein metabolism.88 It was reported that BCAA-enriched total parenteral nutrition resulted in improved protein accretion and albumin synthesis.112 BCAA may also serve to counteract anorexia and cachexia by competing for tryptophan, the precursor of brain serotonin, across the blood-brain barrier and thus blocking increased hypothalamic activity of serotonin (Figure 1). It is known that increased plasma levels of tryptophan can lead to increased CSF tryptophan concentrations and increased serotonin synthesis during cancer.109 Oral supplementation of BCAA successfully decreased the severity of the anorexia in cancer patients.113 Applicable References: 88. Argiles JM, Meijsing SH, Pallares-Trujillo J, et al. Cancer cachexia: A therapeutic approach. Med Res Rev 2001;21:83-101 109. Laviano A, Meguid MM, Yang ZJ, et al. Cracking the riddle of cancer anorexia. Nutrition 1996;12:706-710. 112. Tayek JA, Bistrian BR, Hehir DJ, et al. Improved protein kinetics and albumin synthesis by branched chain amino acid-enriched total parenteral nutrition in cancer cachexia. A prospective randomized crossover trial. Cancer 1986;58:147-157. 113. Cangiano C, Laviano A, Meguid MM, et al. Effects of administration of oral branched-chain amino acids on anorexia and caloric intake in cancer patients. J Natl Cancer Inst 1996;88: 550-552. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.