Is it safe to take L carnitine with levothyroxine (thyroid medication)? 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. How Should I Use Thyroid Supplements? Did you miss this article on John Meadows' www.mountaindogdiet.com ? Dancing with the Devil: L Carnitine (TLDR: L Carnitine might a actually be counteracting your fat loss by *blocking* thyroid action. More is not ONLY NATURAL PET Thyroid Support Supplement for Cats Multivitamin with L Carnitine & Lemon Balm Vet