Carnitine: the claims and why it may not work Most oral L carnitine supplements are glorified flavored chemical waters., , Low bioavailability = very little of it actually gets picked up for use by the body., , So when companies sell $40$60 Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health CARNITOR (levocarnitine) Oral Solution (1 g per 10 mL multidose) L carnitine is effective for both fat loss and athletic performance. However, oral L carnitine has lower bioavailability and can be harmful at high doses, so it should be avoided. , Even cardiologists