Direct effects of thyroid hormones on hepatic lipid metabolism Nature Reviews Endocrinology L Carnitine 500 mg Carnitine Protocol for Life Balance Association between fatigue, peripheral serotonin, and L carnitine in hypothyroidism and in chronic fatigue syndrome American ME and CFS Society 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.