http://dietary-supplements.info.nih.gov/factsheets/carnitine.asp
Office of Dietary Supplements, National Institutes of Health
This site provides information on Carnitine, a dietary supplement, which is derived from an amino acid, found in nearly all cells of the body. Carnitine plays a critical role in energy production. For genetic or medical reasons, some individuals (such as preterm infants), cannot make enough, so for them Carnitine is a conditionally essential nutrient.