Role of L carnitine in exercise training: Anti inflammatory, antioxidant, and metabolic interactions ScienceDirect L Carnitine is often marketed as a fat burner, but most people dont realize that oral and injectable L Carnitine are not the same..Oral L Carnitine has poor absorption (only 20% bioavailability), Assessing the In Vitro and In Vivo Performance of L Carnitine Loaded Nanoparticles in Combating Obesity L carnitine low bioavailability . oral L carnitine 5%