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 Acetyl L Carnitine Acetyl L Carnitine 500 mg Boost Energy & Brain Power with N Acetyl Cysteine & Acetyl L Carnitine Nature's Lab NAC (N Acetyl Cysteine) (120 caps) by Designs for Health IPM Supplements