Did you know L carnitine, a vital amino acid, is naturally produced by your body and found in various foods? While acetyl L carnitine (ALCAR) can be a beneficial supplement for some, most people get Amazon.com: Momentous Acetyl L Carnitine Brain Function & Cognitive Support Supplement Boosts Mental Clarity & Energy Production NSF Certified for Sport 500 mg 60 Servings : Health & Household L Carnitine acetyl L carnitine pathway in coronal mouse brain tissue Download Scientific Diagram Nutrex Research Superior Sports Nutrition Supplements L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.