In a country as fortunate as Australia, you could be forgiven for assuming nutrient deficiencies are a thing of the past. However, recent news of Australian children’s poor performance in Global Education Tests has given some commentators cause to reflect on the question of how diet can affect academic performance. A disappointed Julia Gillard announced the government’s aim for Australian schools to rank among the top five internationally by 2025 – quite a jump, considering that this year our kids came in at 27th in year 4 reading, and 25th in year 4 science. Amongst the reasons suggested for this – including underpaid teachers and lowered standards in university entrance – the under-consumption of the nutrient iodine was pinpointed as a contributing factor. It would, of course, be naïve to blame one factor in isolation for Australian schools’ miserable results, however in light of the proven rates of near or full-blown iodine deficiency across our country, it’s certainly an aspect that needs to be considered.
So what is iodine?
Iodine is a mineral involved in the production of thyroid hormones, which in turn lead to normal growth and development of body tissues and the brain. The World Health Organisation claims iodine deficiency is the biggest cause of mental retardation in the world, particularly in unborn babies of pregnant women: lack of iodine in a developing foetus can result in permanent brain damage (cretinism) or stillbirth. In children and adults, the body may compensate for the lack of iodine with an enlarged thyroid gland (a goitre), a condition commonly associated with the people of developing countries.
Iodine is found naturally in seafoods such as salmon and oysters, as well as in seaweed, all of which feature prominently in the diets of people in countries such as Korea and Hong Kong, both of which can also boast strong performances in international education rankings. Iodine levels in soil can also influence mineral levels in root vegetables.
Other than this, all regular table salt in Australia and worldwide is mandatorily fortified with iodine. This was a logical choice, salt being a shelf staple, affordable, widely used and unaffected in taste or appearance by fortification. Since 2009, Food Standards Australia New Zealand (FSANZ) has ensured that all bread is made with iodised salt – a move made to tackle the re-emergence of iodine deficiency in both Australia and New Zealand.
Iodine content in foods: (RDI being 150g/day for adults)
|Sushi (with seaweed)||90g|
|Cheese – Chedder||23g|
Are our kids really deficient?
Between 2003 and 2004, the Australian National Iodine Nutrition Study surveyed almost 2000 year 4 students from New South Wales, Victoria, South Australia, Western Australia and Queensland. The study aimed to evaluate the incidence of iodine deficiency in the country by measuring both iodine levels and thyroid volumes. The results were worrying. Overall, each of the five states tested were ‘borderline iodine deficient,’ with almost half (46.3%) testing mild – moderately iodine deficient. Considering the imperative role iodine plays in mental development, these results in school children are alarming.
A study carried out in New Zealand used iodine supplementation to determine its effect on cognition in school children aged between 10-13. As expected, those who received the supplement not only experienced increased iodine levels, but also improved cognitive results, while the control group who received a placebo showed no change in results.
Why are we deficient?
So with measures taken to reduce the inadequacies of the mineral in our diet, why are we still lacking in iodine? Strangely enough, the biggest contributor may be due to changes in the dairy industry. Half a century ago, dairy farms frequently used sanitisers containing iodine. An unintended consequence of this was that the mineral seeped into our dairy products, which then became Australia’s main source of iodine. The importance of this unwitting supplementation was made evident when sanitisers were changed to a more cost effective chlorine-based cleaner, after which iodine deficiencies began to resurface.
How about iodised salt? Although it is widely available across the country, are people actually using it? The influence of TV chefs and advertising might perhaps account for many of those who choose sea salt over common, not-so-glamorous table salt – the former of which usually remains unfortified. Furthermore, there’s the bad rap salt receives by health experts, including the government-run Dietary Guidelines. The constant reminders to limit salt use to prevent conditions such as hypertension and diabetes mean that people may avoid its use altogether.
So what’s the answer?
To ensure you’re reaching the recommended 150 micrograms (for adults) a day:
- Ensure the salt you buy and use is fortified.
- Increase your intake of seafood.
- Check that your bread uses iodised salt – many organic breads do not.
And above all, aim to eat a varied diet consisting of the five major food groups.
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