For hundreds of years, iodine has been known as the element that is necessary for thyroid hormone production. Altough iodine has other positive effects in the body, they are often overlooked or not mentioned. The World Health Organisation has recognised that iodine deficiency is the world’s greatest single cause of preventable mental retardation. Approximately one-third of the world’s population lives in iodine deficient areas and up to 72% of the world’s inhabitants is affected by an iodine deficiency disorder. Read on to understand why this is happening.