The iodine status of children in New Zealand has been improved with the mandatory use of iodised salt in commercial bread since 2009, but many remain mildly deficient in this essential nutrient, new research suggests.
In a study conducted by researchers at the University of Otago, the children’s median level of a short-term marker, urinary iodine concentration, was almost double that found in a 2002 study. It now falls just within the range for adequate iodine status.
The study measured biochemical markers of iodine status in 147 primary students from 18 randomly selected Dunedin and Wellington schools between November 2010 and February 2011. The children were aged between 8 and 10.
The researchers found that the median level of thyroglobulin (Tg) concentration in the children’s blood was still in a range indicating mild iodine deficiency in the children.
Tg is a protein produced by the thyroid gland and has been proposed as a longer-term marker for iodine status.
Dr Sheila Skeaff, lead author and senior lecturer at the Department of Human Nutrition, said that while it was pleasing that mandatory fortification of bread has had a positive impact, there was room for improvement.
“The raised Tg levels we found suggest that some New Zealand children may still have enlarged thyroids because they are not getting enough iodine,” she said.
As per a study published in 2009 and authored by Dr Skeaff and colleagues, it was revealed that correcting mild iodine deficiency led to small but significant improvements in children’s performance in cognitive tests.
“There are a number of steps parents can take to increase their children’s iodine intake. For example, if salt is used in preparing meals or at the table it should always be iodised. Dairy products, eggs, fish and other seafood are also good sources of iodine,” said Skeaff.
Skeaff said that it is important that children who eat little or no commercial bread products, which are now the main source of dietary iodine, get a sufficient intake from elsewhere.
“Our results also suggest that fortifying other staple foods needs to be considered if we want to ensure that New Zealand children have good iodine status,” she added.
British Journal of Nutrition
‘Mandatory fortification of bread with iodised salt modestly improves iodine status in schoolchildren’
Authors: Sheila A. Skeaff and Emily Lonsdale-Cooper