Iodine deficiency can cause mental retardation and brain damage yet, alarmingly, it's on the rise in Australia. With up to 50% of children and 25% of adults affected, it's fast emerging as our next big health issue.
Changes in diet and manufacturing practices have created a new health issue in Australia. Iodine deficiency is a re-emerging problem, and is fast becoming a major one. The Australian National Iodine Nutrition Survey 2003-2004 found that almost 50% of school children are mildly to moderately deficient in iodine – which is enough of a deficiency to reduce IQ scores by 10-15% when compared with healthy children. Furthermore, 20% of pregnant women and more than 25% of 'healthy' Australians are affected.
Why is iodine important?
Iodine is vital for a healthy functioning thyroid gland – that small butterfly-shaped gland at the front of your neck. The hormones secreted from the thyroid gland control metabolism, and are essential for healthy growth and development of the brain. One teaspoon of iodine is all you need in a lifetime, yet iodine deficiency at critical stages of development – such as in foetal life and early childhood – can cause lifelong mental retardation.
Why has iodine deficiency become so common?
While the decline in the iodine status of Australians is not completely understood, changes to our food supply may form the best answer. Firstly, the dairy industry has reduced the use of iodine-containing sanitising agents, leading to less iodine in milk.
Secondly, while most people consume too much salt, only 10% of us purchase iodised salt, opting instead for sea or river salt. At the same time, the salt added to our food during processing is also mostly uniodised.
Finally, it is also possible that there has been a decrease in iodine levels in Australian soils.
Iodine deficiency through the stages
If a growing foetus is not exposed to enough thyroid hormones – and therefore iodine – it may not survive or may develop permanent mental retardation. Low birth weight may also result.
Severe iodine deficiency can affect a child's development, giving rise to cretinism (severely stunted physical and mental growth). Symptoms of mild deficiency are less obvious, but include poor school performance and reduced intellectual ability.
Severe iodine deficiency can increase the thyroid gland, causing a goitre - a large swelling on the neck - to form.
Maternal iodine deficiency may cause miscarriage, premature delivery and infertility. It can also be damaging to the mental development of the foetus.
Where can I find iodine?
Iodine is found in seawater, so all seafood and seaweed contain iodine. Sea salt is not a good source, so use iodised salt (in moderation). Milk, yoghurt and some vegetables have small amounts. Under the Food Standards Code, iodine may be added to dairy products such as milk, cheese and yoghurt, as well as beverages such as Milo B-Smart. Iodine fortification of bread is currently being discussed by the Department of Health.