The number of countries where iodine deficiency is a public health problem has halved over the past decade, says the World Health Organization (WHO) in a new global report on iodine status.
Iodine deficiency is a significant cause of mental developmental problems in children. The main strategy - universal salt iodization - has been successful. However, 54 countries are still iodine-deficient and sustained efforts are required to strengthen salt iodization programs, according to the report, Iodine status worldwide.
"Iodine deficiency is a major threat to the health and development of people worldwide, particularly preschool children and pregnant women," said Dr LEE Jong- wook, WHO Director-General. "This report shows that the goal of eliminating iodine deficiency around the world is within reach." Deficiency results when the soil is poor in iodine, causing a low concentration in food products and insufficient iodine intake in the population. When iodine requirements are not met, the thyroid may no longer be able to synthesize sufficient amounts of thyroid hormone. The resulting low-level of thyroid hormones in the blood is the principal factor responsible for the series of functional and developmental abnormalities, collectively referred to as iodine deficiency disorders.
Cretinism is the most extreme manifestation of iodine deficiency, but the primary motivation behind the current worldwide drive to eliminate iodine deficiency is the more subtle degree of mental and neurological impairment leading to poor school performance, reduced intellectual ability and impaired work capacity.
WHO recommends universal salt iodization, namely the use of iodized salt for human and animal consumption, to prevent and control iodine deficiency. This strategy has been implemented in most countries where iodine deficiency is a public health problem under the leadership of UNICEF and WHO. Globally, UNICEF estimates that 66% of households now have access to iodized salt.
The new WHO report estimates the iodine status of the population worldwide and the progress made by each country over the last decade towards achieving the goal of eliminating iodine deficiency. The report is based on the WHO Global Database on Iodine Deficiency, which compiles data on urinary iodine concentration and the prevalence of goitre (enlarged thyroid gland) and monitors the magnitude, severity and distribution of iodine deficiency worldwide. The database is maintained thanks to the financial support of UNICEF.
The number of countries where iodine deficiency is a public health problem was reduced to 54 in 2003, from 110 in 1993, showing the effectiveness of the universal salt iodization strategy, says WHO. Of the 126 countries for which data was available in 2003, iodine intake is now adequate in 43. Of the 54 iodine-deficient countries, 40 are mildly iodine deficient and 14 moderately or even severely iodine deficient. Salt-iodization programmes need to be further strengthened in these countries.
In 29 countries, iodine intake was slightly too high or even excessive. Daily iodine intake above a safe level may result in iodine-induced thyroid dysfunction in susceptible groups. This highlights the important need to reinforce the monitoring of iodized salt quality so that the level is adequate to ensure optimal iodine nutrition but not too high. WHO also emphasizes that promoting iodized salt should not lead to the over-consumption of salt, which can contribute to hypertension: salt iodization can be carried out with a level of salt consumption compatible with WHO's recommendations of up to 5 g/day.
In order to meet the goal of eliminating iodine deficiency by 2005 adopted by the United Nations General Assembly at the Special Session for Children in 2002, WHO faces a dual challenge: first to continue to maintain the Global Databank on Iodine Deficiency in order to monitor and track progress made by countries. To achieve this, WHO is encouraging Member States to reinforce the effectiveness of their iodine nutrition status surveillance systems. Second, to assist Member States to ensure that populations at risk have access to iodized salt by working closely with governments and WHO's partners in the area of iodine deficiency. These include in particular UNICEF, nongovernmental organizations such as the International Council for Iodine Deficiency Disorders, the Micronutrient Initiative, Kiwanis International, and the salt industry, which make up the Global Network for the Sustained Elimination of Iodine Deficiency.