L-Leucine is an essential amino acid that cannot be synthesized by the human body and must be obtained through diet or supplementation. It is one of the three branched-chain amino acids along with L-isoleucine and L-valine and is found in high concentrations in muscle tissue. 61-90-5 L-Leucine is widely used in the food and supplement industries due to its numerous health benefits, including stimulating muscle protein synthesis, reducing muscle breakdown, promoting muscle recovery, and improving exercise performance. It is also involved in regulating blood sugar levels, promoting wound healing, and enhancing immune function.