Thyroid Formula from Doctors Nutra- Zinc Oxide and Copper Oxide FREE, Vegetarian - Gluten Free. In the Journal of Nutrition 129, 12, D.H. Baker states directly that “Copper Oxide Should Not Be Used as a Copper Supplement for Either Animals or Humans”. Doctors Nutra Thyroid supplement contains no Copper Oxide and no Zinc Oxide, but instead utilizes the highest bioavailable forms, Copper Gluconate and Zinc Orotate. The Iodine in our thyroid complex is vital to the creation of thyroid hormones that control much of the body’s functions.