L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Your body already makes L Carnitine, so why do people take it as a supplement? Because while it helps burn fat for energy, it only works when paired with the right lifestyle., So before you jump on Frontiers Discovery and validation of acetyl L carnitine in serum for diagnosis of major depressive disorder and remission status through metabolomic approach Didn't another study show carnitine was good for the heart?