The bright and the dark sides of L carnitine supplementation: a systematic review Journal of the International Society of Sports Nutrition Springer Nature Link L Carnitine and Creatine are both game changers for fitness, but they each shine in different ways! SAVE this as your quick guide! L Carnitine, found in red meat, fish, and chicken, supports fat Understanding the Role of Carnitine in TPN and IDPN Therapy 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.