l Carnitine Supplementation in Recovery after Exercise L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Why the l carnitine sport supplement is controversial 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. Carnitine Deficiency: What Is It, Causes, Symptoms, and More Osmosis