Micronutrient deficiencies
Iodine deficiency disorders (IDD)
Iodine deficiency is the greatest cause of preventable mental retardation in the world. Together with the International Council for Control of Iodine Deficiency Disorders (ICCIDD) and United Nations Children’s Fund (UNICEF), WHO is at the forefront of a worldwide public health drive to eliminate IDD, which is underpublicized yet devastating. WHO provides both technical tools – scientifically sound standards, guidelines and methodologies – and technical guidance to build up national salt iodization programmes.
The challenge
In 2004, it was estimated that 2 billion people were at risk of iodine deficiency and 20% were in the WHO European Region. These people live in iodine-deficient environments, which make them susceptible to endemic goitre, cretinism, mental deficiency, decreased fertility, and perinatal and infant death. Children with IDD and its resulting hypothyroidism can suffer from stunted growth, with mental retardation and problems in movement, speech or hearing.
Iodine is obtained primarily from food, and people in areas near the ocean where soils have higher contents of iodine are less prone to IDD. Low iodine concentrations in soil and water result in iodine deficient plants and animals The soil in large areas of the globe is deficient in iodine. It is estimated that close to one third of the world’s population, affecting 130 countries, live in areas of deficiency.
The most susceptible group for IDD is women of reproductive age, whose neonates, if iodine deficient in utero, are at high risk of irreversible mental impairment. Moreover, the other susceptible group is women providing breast milk to their children, as this may be the only source of iodine for an infant during the first 6 months of life.
When a woman with iodine deficiency becomes pregnant, she risks miscarriage, stillbirth and mental retardation of the child. Even what is considered a mild iodine deficiency can affect the growth of children’s brains, reduce their IQ and cause learning disabilities. In fact, the percentage of iodine-deficient pregnant women has possibly increased in some countries and regions; this causes particular concern as maternal iodine deficiency is well documented to be particularly dangerous to a developing foetus.
WHO’s response
Salt iodization is the preferred strategy for control of IDD and is implemented in more than 120 countries around the world. It is very simple, universally effective, easy and cheap to implement. Many countries worldwide have successfully eliminated IDD or made substantial progress in their control, largely as a result of salt iodization.
In 2014, WHO issued new guidelines on the fortification of food-grade salt with iodine for the prevention of IDD to help Member States and their partners design, implement and scale up iodization programmes. Furthermore, WHO has demonstrated the compatibility of iodization with simultaneous policies targeting reductions in the population-level intake of salt. It has been established that iodization methods can provide the recommended concentrations of iodine for the <5g of salt intake per day that WHO recommends as part of a healthy diet.
