Ingredient Type: ConstituentAlso Known As: Desiccated thyroid, Thyroid extractThyroid is desiccated bovine thyroid gland tissue, where the thyroid glands are dried and powdered for therapeutic use. These animal extract thyroid preparations were developed in the late 19th century, and are still in use today. Thyroid is used in health supplements to support natural thyroid gland function. MORE COMING SOON In the meantime see this Naturopath authored article on glandular therapy for more information.