L Carnitine 1000mg Energy, Metabolism & Fat Burning PCOS Nutrition Center L Carnitine (120 Capsules) Amazon.com: NOW Foods Supplements, Acetyl L Carnitine 500 mg, Amino Acid, Brain And Nerve Cell Function*, 200 Veg Capsules : Health & Household L Carnitine Benefits: A Complete Research Based Guide 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. Liquid L Carnitine Energy, Metabolism & Fat Burning