L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active Function of carnitine in the transport of mitochondrial long chain Download Scientific Diagram Carnitine Shuttle an overview ScienceDirect Topics L Carnitine helps shuttle fatty acids into the mitochondria (the power plants of your cells) where they can be burned for energy. It's often used in fat metabolism and energy support formulas.