Beta-alanine is a non-proteogenic amino acid that is produced endogenously in the liver. In addition, humans acquire beta-alanine through the consumption of foods such as poultry and meat. By itself, the ergogenic properties of beta-alanine are limited; however, beta-alanine has been identified as the rate-limiting precursor to carnosine synthesis, and has been consistently shown to increase levels of carnosine in human skeletal muscle. Doses of 4 to 6 g/day of beta-alanine have been shown to increase muscle carnosine concentrations by up to 64 % after 4 weeks, and up to 80 % after 10 weeks. Baguet et al. demonstrated that individuals vary in the magnitude of response to 5 to 6 weeks of betaalanine supplementation (4.8 g/day), with high responders increasing muscle carnosine concentrations by an average of 55 %, and low responders increasing by an average of only 15 %. The difference between high and low responders seems, at least in part, to be related to baseline muscle carnosine content and muscle fiber composition.
