L-Isoleucine is an essential branched-chain amino acid (BCAA) that plays a crucial role in protein synthesis and muscle metabolism. It is involved in energy production, particularly during exercise, and helps regulate blood sugar levels. Isoleucine plays a role in the synthesis of hemoglobin and is important for immune function. It works synergistically with the other BCAAs (leucine and valine) to support muscle growth and recovery.