The importance of Iodine


Iodine is found in seafood, kelp, eggs, bread and some vegetables. But in decades past, most of us got much of our iodine in our diet in two ways - from iodised salt, and through iodine-containing sanitisers used in milk production. These days, the dairy industry no longer uses these sanitisers, and more than 80% of Australian families (and our food manufacturers) don’t use iodised salt. You probably use rock salt or sea salt in your home, and most of these do not contain any iodine. Because of this, iodine intake has more than halved over the last ten years.

These changes have led to some drastic effects in terms of iodine levels in the body. There is now irrefutable evidence that iodine deficiency is widespread in Australia. The World Health Organization (WHO) classifies the Australian population as mildly iodine deficient. Several studies have shown the reemergence of mild-to-moderate iodine deficiency in school-aged children, healthy adults and pregnant women. Studies of pregnant Australian women show that their estimated daily iron intake is about half of the recommended daily requirement.

So, what’s the big deal about iodine? Why is it so important to pregnant and lactating women?

Iodine is one of the main components of thyroid hormones (Thyroxine, or T4, and T3) which regulate much of our metabolism and promote the growth and development of our brains and bodies. Iodine deficiency reduces the amount of thyroxine that the fetus receives. This is vital to the development of the brain and body in babies and young children. A reduced amount of thyroxine can cause stunted growth, diminished intelligence and mental retardation (sometimes known as cretinism). These changes are usually irreversible.

In fact, iodine deficiency is the commonest cause of preventable intellectual impairment around the world. In places where iodine deficiency is severe (and Australia does not fall into that category) IQ scores in children are reduced by between ten and fifteen points.

As well as the intellectual impacts, hearing can also be impaired. There may be a link between iodine deficiency and Attention Deficit Hyperactivity Disorder, or ADHD. The World Health Organisation (WHO) recognises iodine deficiency as one of the major world public health issues.

So, to ensure the unborn child is protected from these adverse and irredeemable effects, pregnant women or mothers who are breastfeeding need sufficient iodine. An average adult needs a minimum of 150 micrograms of iodine per day. But women who are pregnant or breastfeeding need at least 250 micrograms every day. There are no concerns about the safety of iodine supplements at these dosages.

Of course not all women will have an iodine deficiency. And the good news is that there are several ways improved iodine levels can be achieved. You can increase your iodine intake by dietary means. However, be wary of kelp and seaweed extracts, which may contain large amounts of iodine and other contaminants. Since October 2009, iodised salt has replaced non-iodised salt in all bread sold in Australia, except organic bread. You can use iodised salt rather than untreated salts. Or you can take iodine supplements. Pregnancy and breastfeeding vitamins now contain iodine at appropriate levels, usually 150 micrograms. Your GP or obstetrician will be able to help you with addressing any iodine deficiency you may have.

The exception to iodine supplementation is for those women with pre-existing thyroid disease - they should be individually managed to ensure normal thyroid function during pregnancy.

This is an important issue. The evidence of significant and increasing iodine deficiency in pregnant and lactating women in Australia is too conclusive to ignore. If you’re pregnant or breastfeeding, talk to your GP or obstetrician about your thyroid function and iodine levels.