Carnitine, a derivative of the amino acid lysine, carries activated fatty acids through the mostly impermeable inner mitochondrial membrane, allowing the respiration of fatty acids. Carnitine was initially believed to be a vitamin called “vitamin BT”. It was discovered humans can synthesize L-carnitine, although under certain conditions and depending on the diet the demand for L-carnitine may exceed an individual's capacity to synthesize it. This makes it a conditionally essential nutrient. This active improves the tone and texture of the skin. It is also a powerful antioxidant that reduces free radicals formed by the sun, pollution, and heat.