L Carnitine: The Energy Booster Your Body Loves Turn fat into fuel and power up your recovery with one of our favorite performance vitamins. Boosts metabolism & fat burning Corebolics L Carnitine Liquid (450 ml, 30 serving) Acetyl L Carnitine 1000mg Brain, Energy, Metabolism Support Purecell Supplements Nature's Bounty L Carnitine 500 Mg 30 Tablets Nahdi L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.