Carnitine is found in almost all cells of the body and plays an important role in the production of energy. It transports long-chain fatty acids into the mitochondria so they can be oxidized, or burned, to release energy. L-carnitine is synthesized in the brain, liver, and kidneys from the amino acids methionine and lysine and is vital to heart and brain function, muscle movement, and several other processes in the human body. Insufficient levels of carnitine can lead to problems in the liver, heart, and muscles