University of Otago researchers are hoping to replicate a ground-breaking study linking iodine to intelligence, this time with adults.
Principal investigator Dr Sheila Skeaff, of the department of human nutrition, said if the trial did show a link she hoped the Government would make food manufacturers use iodised salt in processed food.
The researchers' previous study, of children aged 10 to 13 in 2007 and 2008, found iodine tablets improved intelligence, particularly problem solving.
Now researchers want to determine whether there are similar effects in adults aged 18 to 30.
Dr Skeaff said, as most types of bread were required to be iodised as of September 2009, subjects should consume two or fewer slices a day to maintain healthy iodine levels.
Before bread fortification, most New Zealanders were mildly iodine deficient, and still would be if they did not consume enough bread, Dr Skeaff said.
She said salt was in a host of processed foods, and it would be good if manufacturers were forced to used iodised salt.
Such regulation was common overseas, and should be in New Zealand because its soil was iodine deficient.
Dr Skeaff said, as the brain developed until about the age of 40, it was possible iodine continued to play a role among the older age group.
She was teaming up with Associate Prof Ted Ruffman, of the psychology department, to conduct the trial of about 200 people, of whom about 50 were still being sought.
The study is already under way, and preliminary results should be known by the end of next year, she said.
