Myo Flex Nutrition Matrix Whey is High-Quality Whey protein contains all nine essential amino acids, making it a complete protein. Essential amino acids cannot be synthesized by the body and must be obtained through diet. Rich in Branched-Chain Amino Acids (BCAAs): Whey protein is particularly high in BCAAs, including leucine, isoleucine, and valine. Leucine, in particular, plays a critical role in stimulating muscle protein synthesis, which is the process by which the body repairs and builds new muscle tissue.