Branched Chain Amino Acid Powder 12 oz by NOW FoodsOf the eight essential amino acids that cannot be produced by the body, the three branched chain aminos Leucine, Isoleucine and Valine are of key importance. Based on their unique structure, activity, storage and metabolism, BCAA's have become a staple in the lives of many athletes and physically active individuals. They account for nearly 1 3 of the amino acids in muscle protein, and play a number of key roles in the repair and growth of muscle