Iodine is an essential element needed for the production of thyroid hormone, which controls metabolism and plays a major role in fetal neuro development. Its ionized form is called iodide. Iodine deficiency results in im-pairment of thyroid hormone synthesis and may lead to several undesirable consequences. 

    Children born in iodine deficient areas are at risk of neurological disorders and mental retardation because of the combined eVects of maternal, fetal, and neonatal hypothyroxinaemia. The reasons are that iodine is required for the synthesis of thyroid hormones and that thyroid hormones,in turn, act by regulating the metabolic pattern of most cells of the organism. They also play a determining part in.

     In 1990, 1.6 billion people, that is 28.9% of the earth’s population, were at risk of iodine deficiency,7 which therefore appeared as the world greatest single cause of preventable brain damage and mental retardation.

     The process of early growth and development of most organs, especially of the brain,2–4 which occurs in humans during fetal and early postnatal life. Consequently, iodine deficiency, if severe enough to aVect thyroid hormone synthesis during this critical period, will result in hypothyroidism and brain damage. The clinical consequence will be mental retardation.µg/day from 0 to 6 months, 90 µg/day from 6 months to 6 years, 120 µg/day from 7 to 10 years, 150 µg/day during adolescence and adulthood, and 200–300 µg/day during pregnancy and lactation.When these physiological requirements are not met in a given population, a series of functional and developmental abnormalities occur, including thyroid function abnormalities and, when iodine deficiency is severe, endemic goitre and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death and infant mortality. These complications,which constitute a hindrance to the development of the aVected populations are grouped under the general heading of iodine deficiency disorders.

     The World Health Organisation (WHO), the United Nations Children’s Fund (Unicef), and the International Council for Control for Iodine Deficiency Disorders (ICCIDD) have defined three degrees of severity of iodine deficiency: mild (iodine intake of 50–99 µg/day), moderate (20–49 µg/day), and severe (<20 µg/day).

    Chinese researchers have found that children living in iodine-deficient areas with no iodine supplementation/fortification had an average of 12.45 intelligence quotient points less than children living in an iodine-sufficient environment . IDD in pregnant women causes increased pregnancy loss and infant mortality,cretinism and neonatal hypothyroidism in their children . Even mild deficiency in women during pregnancy has been found to cause subsequent educational and cognitive impairments in their children . Iodine deficiency is one of the most common micronutrient deficiencies in the world.

    Iodine deficiency has been recognized as a severe public health problem in China since the 1930s.Data collected between the 1960s and 1990s recorded iodine deficiency of varying degrees in all of China’s provinces . In many endemic areas, 5%–15% of children suffered from mild retardation (intelligence quotient of 50–69) .

    As a result of these data demonstrating a significant IDD problem, salt iodization interventions were started in endemic areas of China in the 1960s. In 1993, as a follow up to the 1990 United Nations Summit for Children, the National Advocacy Programme for the Elimination of IDD by 2000 was launched.