Branched-chain amino acids (leucine, isoleucine, and valine) and skeletal muscle

The branched-chain amino acids (BCAAs), leucine, isoleucine, and valine, comprise ~17% of human skeletal muscle. BCAAs are essential amino acids that need to be provided by dietary protein. Dietary protein-derived amino acids are transported via the circulation to skeletal muscle where they are used to support protein synthesis. Besides serving as substrate for protein synthesis, the BCAA leucine acts as a signaling molecule that activates the muscle protein synthetic machinery. This chapter provides an overview of the current understanding of the role of BCAAs in stimulating muscle protein synthesis and promoting muscle growth. In addition, BCAA catabolism will be addressed, and we will discuss the hypothesis that BCAAs may play a role in the development of insulin resistance.