− | Iodine is essential because it is a major constituent of the '''thyroid hormones''' thyroxine (T<sub>4</sub>) and 3,5,3’-triiodothyronine (T<sub>3</sub>), the latter being considered the active form of the hormone. | + | Iodine is [[Nutrition Glossary#Essential Nutrients|essential]] because it is a major constituent of the '''thyroid hormones''' thyroxine (T<sub>4</sub>) and 3,5,3’-triiodothyronine (T<sub>3</sub>), the latter being considered the active form of the hormone. |