Adding L Carnitine and Selenium to Methimazole in Graves' Disease: A Prospective Randomized Trial on Thyroid Markers and Quality of Life Thyroid Supplement with L Carnitine for Cats Only Natural Pet 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. Role of carnitine in disease Nutrition & Metabolism Springer Nature Link