It is estimated that around 2 billion people worldwide may have an insufficient intake of iodine. Iodine is essential for the synthesis of the thyroid hormones thyroxine (T4) and tri-iodothyronine (T3), and there is increasing evidence for its importance in the early growth and development of many organs, including the brain and central nervous system.
A deficiency of iodine during pregnancy can lead to conditions such as maternal and foetal goitre, hypothyroidism, intellectual impairment, psychomotor defects and cretinism, a severe and irreversible form of mental retardation characterised by multiple neurological defects such as deaf-mutism, diplegia and squint, as well as dwarfism. On top of this, the risk of miscarriage, still birth and infant mortality is increased. Goitre, hypothyroidism and impaired cognitive function do not just affect infants either – they have also been noted to occur in childhood, adolescence and adulthood when iodine intake is insufficient.