L Carnitine Oral Bioavailability NOW l Carnitine Supplement Usefulness of Carnitine Supplementation for the Complications of Liver Cirrhosis L Carnitine Supplementation in Patients with Advanced Cancer and Carnitine Deficiency: A Double Blind, Placebo Controlled Study ScienceDirect Why is L carnitine used for Medium Chain Acyl CoA Dehydrogenase (MCAD) deficiency? If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.