β-Alanine-13C3,15N is the isotope labeled analogue of β-Alanine (A637320), which is a naturally occurring beta amino acid. β-Alanine is formed in vivo by the degradation of Dihydro Uracil (D449990) and Carnosine. β-Alanine is also the rate-limiting precursor of Carnosine, as a result supplementation with β-Alanine increases the concentration of Carnosine in muscles.