Frontiers The effects of L carnitine supplementation on glycemic markers in adults: A systematic review and dose response meta analysis L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy. Vitacost Acetyl L Carnitine HCl 500 mg 300 Capsules Vitacost Carnitine for your metabolism TISSO Naturprodukte A Guide to L Carnitine on Keto Keto Nutrition Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health