Australian children suffering from iodine deficiency

Thursday, February 23, 2006 

Almost half of all Australian primary school children are mild to moderately iodine deficient, researchers say. A new study documenting iodine nutritional status in Australian schoolchildren has revealed many are not getting enough iodine - which can lead to mental and growth retardation. The report's authors say iodine deficiency is "the sleeper health issue in Australia", and potentially a very serious one.

The results of the Australian National Iodine Nutrition Study published in the Medical Journal of Australia this week, revealed that children in mainland Australia are borderline iodine deficient. The report has prompted calls for all edible salt to be iodised. They say adding the mineral to salt is the simplest and most effective method of preventing iodine deficiency disorders.

A cross-sectional survey of 1709 schoolchildren - aged 8–10 years, from 88 schools - was carried out in New South Wales, Victoria, South Australia, Western Australia and Queensland, between July 2003 and December 2004. Tasmania was excluded from the study - where an voluntary iodine fortification program using iodised salt in bread, is ongoing.

The authors say the results confirm the existence of inadequate iodine intake in the Australian population. They call for "urgent implementation of mandatory iodisation of all edible salt in Australia." Most iodine in food comes from seafood, milk and iodised salt.

Professor Cres Eastman, Director of the National Iodine Nutrition study, and Chairman of the Australian Centre for Control of Iodine Deficiency Disorders, says it is crucial that children and pregnant women in particular have an adequate intake of iodine. Iodine deficiency can lead to serious health problems including brain damage, stunted growth and deafness.

Professor Eastman says manufacturers could easily remedy the situation by using iodised salt in their products in line with the United States and most European countries. "I suspect they won't do that on a voluntary basis, we've tried so far and haven't succeeded, so we've convinced the Food Standards of Australia and New Zealand| that all salt should be iodised," he said.

The report says the decline in iodine intake appears to be due to changes in the dairy industry, where chlorine-containing sanitisers have replaced iodine-containing sanitisers. Iodine released from these chemicals into milk has been the major source of dietary iodine in Australia for at least four decades, but is now declining. Another contributory factor has been the decreasing consumption of iodised salt used in foods. The report states that few if any food manufacturers use iodised salt in the preparation and manufacture of foods.

Professor Eastman says iodine is added to only 10 per cent of Australian salt in contravention of a World Health Organisation recommendation that all salt be iodised. He says authorities are reacting slowly to his urgent calls for mandatory iodised salt.

"The effects of iodine deficiency are dependent upon how severe it is and when it occurs. So if we go to the pregnant woman, she doesn't get enough iodine, she won't make enough thyroid hormone, and the foetus won't get the amount of thyroid hormone it needs for adequate and proper development of the brain, so you'll then see consequences being loss of IQ, learning difficulties, hearing difficulties and other neurological problems," Professor Eastman said.

"If an infant's not getting enough iodine... brain development won't be completed and they won't grow normally, and as you get older the problem will be that you will develop a goiter and your thyroid won't function as well as it should, so that may have all sorts of pernicious effects upon normal function in life."

More than two billion people around the world live in areas prone to iodine deficiency, and yet the problem is easily fixed. The World Health Organisation (WHO) recommends that every country should iodise all edible salt. The most well known effects of IDD are visible goiter and cretinism, a condition characterised by severe brain damage occurring in very early life. WHO say Iodine deficiency is the world’s most prevalent, yet easily preventable, cause of brain damage.

Professor Eastman said he is alarmed by what they found. "Pregnant women in Australia are getting about half as much as what they require on a daily basis. So that alarms me, because there's quite serious potential for adverse effects and brain damage in the next generation of children born in this country," he said. "If Iodine deficiency is serious you lose 15 IQ points, on average. There shouldn't be anyone suffering from iodine deficiency in a developed country like Australia."

Lydia Buchtmann for Food Standards Australia New Zealand, says they are looking at mandatory guidelines on iodine by the end of the year. She says the issue is complicated and will take time to get right. We need to "make sure there's sufficient iodine added into the food supply, to help those people with a deficiency. But at the other end of the scale we've got to make sure the people who eat a lot of food - we all know the teenage boy who comes home from school and eats a whole loaf of bread - that those people don't get too much and get overdose," Ms Bauchtman said. "One of the reasons that iodine is going down is because people are taking that good healthy eating message and not adding salt during cooking."

Senior researcher Mu Li, of the University of NSW's school of public health, said "it is reasonable to assume that pregnant women and breastfeeding mothers are also iodine deficient, putting the next generation of children born in this country at risk of the neuropsychological consequences of iodine deficiency."

Sources

• Reporter: David Mark. "Report finds iodine deficiency in Australian children" — The World Today - ABC Radio, February 20, 2006
• "Results of the Australian National Iodine Nutrition Study" — The Medical Journal of Australia, February 20, 2006
• "Children's diets too low in iodine" — Australian Broadcasting Corporation, February 20, 2006
• "Children's development at risk from iodine deficiency" — Sydney Morning Herald, February 19, 2006
• "Iodine deficiency disorders" — World Health Organization, 2006