L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Carnitine supplementation improves metabolic flexibility and skeletal muscle acetylcarnitine formation in volunteers with impaired glucose tolerance: A randomised controlled trial eBioMedicine L Carnitine has become one of our top 5 sellers the last few years and when you review the research, you can see why. L carnitine is a supplement probably more well known if L carnitine is an amino acid that is produced in your body that helps the body turn fat into energy. Carnitine is found in nearly all cells of the body and researchers have Carnitine supplementation improves metabolic flexibility and skeletal muscle acetylcarnitine formation in volunteers with impaired glucose tolerance: A randomised controlled trial eBioMedicine L Carnitine Fumarate Olympian Labs