Metabolic Optimizer L Carnitine supports cellular energy production. NOW Foods L Carnitine 1000 mg, 50 Tablets Walmart.com L Carnitine CAM Cancer Doctor's Best L Carnitine Fumarate with Biosint Carnitines, 855 mg, 60 What is L Carnitine? L Carnitine is a naturally occurring amino acid derivative that the human body can synthesize itself. It is mainly found in red meat and dairy products. [1] Core Benefits of Ingredient Spotlight: L Carnitine Source: Biosynthesised in the body from the amino acids Lysine and Methionine, L Carnitine is a conditionally essential nutrient involved in energy metabolism and fat transport. Key Benefits