L-Leucine, L-Isoleucine, L-Valine Pharmaceutical Grade Non-GMO GMP Quality Assured A Dietary Supplement The Branched Chain Amino Acids (BCAAs), Leucine, Isoleucine and Valine are essential amino acids, and thus cannot be made in the body. BCAAs are critical for muscle protein synthesis, and because BCAAs can be used as fuel during intense exercise, BCAA supplementation can help to preserve existing muscle tissue. In addition, BCAAs can support the recovery process by promoting the normal repair processes that take place after exertion. BCAAs also play an important role in the maintenance of proper immune system function and the support of healthy aging.