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Research shows adding iodine to salt may pose risks to some populations

A new study by the Norwegian’s Scientific Committee on Food and the Environment (VKM) concluded that although the addition of iodine to salt used in products throughout the country would benefit adolescents and women of childbearing age, the same increase could also be harmful in infants and small children.

Based on a benefits and risk analysis, the study concluded that achieving the specific iodization level needed for the deficient group cannot be determined without “posing increased risk of harm to others” or “that the benefits in one group outweigh the risks in others.” Infants and small children are at particular risk from over-iodized products due to their lower intake needs, according to the study.

At the same time, the study noted that while certain populations in Norway have “worryingly low” levels of iodine in their diets, there is currently no data on the prevalence of severe iodine deficiency in Norway. Nor could researchers identify any clinical consequences of mild to moderate intake deficiencies of iodine intake. The effects of severe iodine deficiency are well documented and include spontaneous abortion, stillbirth, low birth weight and stunted infant growth.

This research was performed by analyzing scientific papers and publications to evaluate the estimated intakes of iodine in population segments across the country as well as the effect of different scenarios of increasing iodization levels in household salt. While there was “limited” evidence surrounding the effects of hyper-consumption of iodine, the study was able to identify the existence of adverse effects for deficient intakes.

The study did determine that the adequate level of iodization or women of childbearing age and 13-year-olds is between 15 to 20 milligrams of iodine per kilogram of salt. Norwegian law limits the addition of iodine in salt to 5 milligrams, and the iodization of salt is not compulsory in the country.

Other European countries have increased the amount of iodine in salt in order to combat low levels of intake in the general population. Last year the Danish Food Agency increased the required iodine levels in salt from 13 milligrams per kilogram to 20 milligrams per kilogram. The decision was based on a 2013 study that found pregnant Danish women who were not taking iodine supplements remained deficient in the mineral even when ingesting iodine-fortified salt.

Food Navigator reported that Sweden and Finland increased the amount of iodine in salt to 50 and 25 milligrams per kilogram respectively. France and Germany take a voluntary approach to salt iodization.