Potassium plus Iodine by Now Foods 60 Tablet Potassium Iodide (KI) is a compound that contains Iodine a nutient necessary for normal thyroid function. Iodine in the form of Iodide is an integral part of thyroid hormones which regulate cellular metabolism and energy production. NOW Potassium Iodide Plus also supplies Potassium a mineral that is essential for the maintenance of healthy water balance and whole body pH.