Effect of Acute and Chronic Oral l Carnitine Supplementation on Exercise Performance Based on the Exercise Intensity: A Systematic Review 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: DR. MARTIN'S NUTRITION Extra Strength L Carnitine 200 Capsules 1000mg Per Serving Boost Your Metabolism and Increase Performance : Health & Household L Carnitine: Benefits & Supplementation Integrated Mobile Health