Iodine deficiency refers to a condition where an individual's body does not have enough iodine, which is an essential mineral needed for proper thyroid function. The thyroid gland requires iodine to produce hormones that regulate metabolism and growth in the body. When there is a lack of iodine, it can lead to various health problems such as goiter (enlarged thyroid), hypothyroidism (underactive thyroid) or developmental delays in children. Iodine deficiency is most commonly seen in areas where seafood and salt are not consumed regularly, or where there is a lack of access to iodized salt.