Optimum Nutrition's BCAA 5000 Powder provides a 5000 mg blend of the three Branched Chain Amino Acids (L-Valine, L-Leucine and L-Isoleucine) in every serving. The Branched Chain Amino Acids (BCAA's), so named because of their unique branched chemical structure, are essential in that the body cannot make them from other compounds. In recent times, these amino acids have been investigated for their potential anticatabolic (preventing muscle breakdown) and anabolic (muscle building) effects.