Leucine is classified as a branched-chain amino acid (BCAA) and an essential amino acid, meaning it cannot be made by the body, and must be acquired through food or dietary supplements. The branch chain amino acids valine, leucine, and isoleucine enhance protein synthesis in liver cells and muscle cells and help promote muscle recovery after exercise. They contribute to energy production in the body by being oxidized in the cell's mitochondria. Branch chain amino acids are used by body builders and athletes to produce an anabolic effect and assist in the repair of micro tears in muscle tissue that are a normal result of exercise. Leucine is thought to be the most effective BCAA for preventing the body's burning of muscle stores for energy during intense workouts because it is converted to glucose more quickly than isoleucine and valine. NutraBios L-Leucine is non-GMO, gluten free, soy free, third-party tested, made in the USA, and certified kosher.