Iodine is a trace element that is indispensable in the human body. Iodine deficiency refers to a group of diseases caused by natural environmental iodine deficiency or due to insufficient intake. They include endemic goiter, endemic cretinism, fetal miscarriage, premature birth, stillbirth and congenital malformations. Iodine deficiency in newborns mainly causes congenital hypothyroidism. Iodine deficiency in infants and children causes mental retardation or associated neurological damage. Iodine deficiency in adolescents affects intellectual development and physical development, causing motor, visual and auditory impairment and goiter. The main effect of iodine deficiency on adults is goiter.