L Carnitine: Benefits, side effects, and dosage What is carnitine? Carnitine is produced in the body from the amino acid lysine and naturally occurs in some foods. It supports energy metabolism and muscle function, which are important factors in L Carnitine: Benefits, Uses, Side Effects, and More Assessing the antioxidant and metabolic effect of an alpha lipoic acid and acetyl L carnitine nutraceutical ScienceDirect Frontiers Carnitine and Depression