L-carnitine is a vitamin-like molecule that serves numerous functions in the body. Its main function is to stimulate the breakdown of fats. L-carnitine is an alpha-hydroxy acid that is primarily located in muscle. Carnitine is the critical player for the transport of fatty acids into mitochondria. Mitochondria are the powerhouses in the cell that produce the energy your body needs to function properly. This energy is produced when fats are burned in the mitochondria. Since mitochondria need oxygen to burn fat, it follows that supplementation with carnitine ensures an adequate supply of oxygen to the muscle. The supply of oxygen becomes extremely important during exercise.