Acetyl L Carnitine (Metabolic Response Modifier) L Carnitine is Underrated. New Meta Review Reminds Us Why. Pure L Carnitine Tartrate 1000 mg MLnaturals Ingredient Spotlight: L Carnitine Source: Biosynthesised in the body from the amino acids Lysine and Methionine, L Carnitine is a conditionally essential nutrient involved in energy metabolism and fat transport. Key Benefits The effects of L carnitine supplementation in athletic performance ScienceDirect Acetyl L carnitine physical chemical, metabolic, and therapeutic properties: relevance for its mode of action in Alzheimer's disease and geriatric depression Molecular Psychiatry