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: Life Extension Optimized Carnitine, Three Forms of L carnitine, Promotes Heart & Brain Health, Gluten Free, Non GMO, Vegetarian, 60 Capsules : Health & Household The Brain and Mitochondria Boosting Benefits of Acetyl L Carnitine (ALCAR) by Alex Leaf, M.S. The Energy Blueprint 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.