What Is Carnitine and Why Is It Important? The Amino Company Supplement of the week: L Carnitine! This one doesn't just boost fat metabolismit can also improve recovery, endurance, and even brain function. If you're serious about performance and longevity, this might be The Role of l Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.