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 Propionyl l carnitine: Health Benefits, Side Effects, Uses, Dose & Precautions Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications The Role of L Carnitine in Kidney Disease and Related Metabolic Dysfunctions