“Iodised salt for household use is available in most European countries, but unfortunately much of the salt used in food production is not iodised,” said Dr Maria Andersson, lead author of the paper, which was published in the April issue of The Journal of Nutrition.
“The issue of iodine deficiency is unfortunately a low priority in many European countries. Coordinated actions for a common EU policy are needed, particularly for salt used by the food industry.”
Researchers from the Swiss Federal Institute of Technology Zurich and the International Council for the Control of Iodine Deficiency Disorders analysed data from the WHO database, research papers published in peer-reviewed journals and survey reports to document the prevalence of iodine deficiency worldwide.
11 countries in Europe were classified as ‘iodine deficient’, based on the median urinary iodine concentration (UIC), with Russia, Ukraine, the Baltic countries, and the UK and Ireland faring worst in the study.
“In Russia, Ukraine and the Baltic countries, salt iodisation slipped backwards and the dietary iodine intake decreased after the collapse of the Soviet Union,” said Andersson.
“A similar trend is seen in the UK and Ireland where the iodine intake has long been assumed to be adequate, mainly due to sufficient iodine intake from milk, but where the population is now iodine deficient. Iodisation of salt is not regulated in the UK and only about five per cent of all salt sold in the UK is iodised.”
‘Aye’ to mandatory iodine
By contrast, Denmark, where legislation mandates salt used in bread production to be iodised, and Portugal, where iodine supplementation has been introduced for pregnant women, were both found to have ‘optimal iodine nutrition’.
The reason iodine deficiency is a concern is that iodine is a critical component of the thyroid hormones that are need to modulate growth, development and energy metabolism.
“Iodine deficiency has multiple adverse effects on growth and development due to inadequate thyroid hormone production...Iodine deficiency remains a major global threat to health and development, because it is the most common cause of preventable mental impairment...Pregnant women and young children are particularly susceptible,” wrote the authors.
Beside iodised salt, the major dietary iodine sources are bread and milk; bread due to a combination of the native iodine content in grains and the use of iodised salt, and milk due to iodine fortification of cattle feed, explained Andersson.
She dismissed the suggestion that salt reduction drives in some EU countries could be contributing to iodine deficiency, saying: “The low iodine intake in some European countries is likely a combination of low household use and low use of iodised salt by the food industry. Coordinated actions between the food industry (the use of iodised salt at adapted fortification levels) and salt reduction strategies would ensure adequate iodine intake despite a lower salt intake.”