High Quality Content by WIKIPEDIA articles! Iodised salt is table salt mixed with a minute amount of various iodine-containing salts. The ingestion of iodide prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of mental retardation. It also causes thyroid gland problems, including endemic goitre. In many countries, iodine deficiency is a major public health problem that can be cheaply addressed by iodisation of salt.