A LACK of iodine may partly explain why Australian schoolchildren are being beaten in international tests by their counterparts in Korea, Singapore and Hong Kong, an expert on iodine deficiency says.
The Prime Minister, Julia Gillard, has set the goal of Australia's school system being in the world's top five by 2025.
International test results released in December placed Australia 27th in the world in year four reading, 22nd in science and 18th in maths.
Writing for Fairfax Media, Cres Eastman, a professor of medicine at the University of Sydney and an internationally noted expert on iodine deficiency, says the top-performing education systems, including Singapore, Korea and Hong Kong, have diets that are rich in iodine, because of salt iodisation, and the consumption of fish and seaweed.
In contrast, he says a national survey of schoolchildren in 2003-04 has confirmed the re-emergence of iodine deficiency in Australia after an absence of almost half a century.
The main cause is that the dairy industry has stopped using iodine to sterilise milk containers, but this has been compounded by the reluctance of consumers to buy iodised salt for home use, and the fact that the local food industry makes only limited use of iodised salt in food manufacturing.
A spokesman for the Australian Food and Grocery Council said the dairy industry had stopped using iodine - a micronutrient essential for normal thyroid function - as a sterilising agent because of the fluctuations it caused in iodine levels.
Since 2009, Australian regulations have required iodised salt be used in all bread except organic bread.
The World Health Organisation has identified iodine deficiency as the ''commonest global cause of preventable loss of intellectual performance''.
Professor Eastman says research from New Zealand has shown the intellectual performance of children improved after they were given an iodine supplement.