When to take L carnitine: Dosage, forms, and side effects 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 Solaray Acetyl L Carnitine Capsules 500mg, 30 ct Fred Meyer Life Extension Acetyl L Carnitine Cellular Energy, Brain, Nerve Support + N Acetyl L Cysteine Immune, Top 5 Benefits of CoQ10 and L Carnitine Combination for Athletes iThrive Essentials High l Carnitine Ingestion Impairs Liver Function by Disordering Gut Bacteria Composition in Mice Journal of Agricultural and Food Chemistry