An iodide ion is the ion I^-. Compounds with iodine in formal oxidation state -1 are called iodides. This page is for the iodide ion and its salts, not organoiodine compounds. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability.