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 History of L carnitine: Implications for renal disease Journal of Renal Nutrition Acetyl L Carnitine, 500 mg, 200 Quick Release Capsules Acetyl L Carnitine 637.5mg Source of Carnitine Energy & Cognitive Nutridom Acetyl L Carnitine