A concentrated dietary supplement for injection containing the essential amino acids leucine, isoleucine, lysine, valine, phenylalanine, histidine, threonine, methionine and tryptophan as well as the non-essential amino acids alanine, arginine, glycine, proline, serine and tyrosine, with potential anabolic and anti-catabolic activities. Upon dilution and intravenous infusion of the amino acid nutritional supplement, the amino acids serve as protein building blocks, promote protein synthesis in muscle cells and prevent protein breakdown.