L Carnitine Uses & Benefits Explained: A Complete Guide The Science of Good Health Meet L Carnitine a naturally occurring amino acid that plays a key role in helping the body convert fat into usable energy. It works by transporting fatty acids into your cells to Amazon.com: NOW Foods Supplements, Acetyl L Carnitine 500 mg, Amino Acid, Brain And Nerve Cell Function*, 200 Veg Capsules : Health & Household PCOS Nutrition Center L Carnitine Subscription (120 Capsules) PCOS Nutrition Center