When Caryn was five months pregnant she was told by her doctor she had an iodine deficiency. Initially she wasn’t unduly worried. She had worked hard to stay fit and healthy during her pregnancy and was taking some supplements. How could it be serious? Tests had shown her to be mildly to moderately iodine deficient, and alarmingly she was not alone. A nationwide survey of the iodine status of 170 pregnant women in New Zealand undertaken by the University of Otago (Pettigrew Porter et al 2006) showed moderate iodine deficiency to be very common. Why is this deficiency such a huge cause for concern? And how can it be treated?
During pregnancy, thyroid hormone requirements are increased by about 50% over pre-pregnancy levels. A lack of iodine during pregnancy can have a significant impact on the brain development of babies both in-utero and after being born. In addition, young children can experience developmental and learning problems if there is an iodine deficiency. If the deficiency is severe the child may get a condition called iodine-deficiency disorder (IDD). IDD is the single most common cause of preventable mental retardation and brain damage in the world today. However, once the damage is done, it is irreversible.
Iodine is used by the thyroid gland to make thyroid hormone – one of the important hormones that drives our metabolism. With insufficient iodine, the mother (or the infant) can’t make enough thyroid hormone to keep up with the needs of the growing brain. If hypothyroidism, (that is, insufficient thyroid is produced), develops early in pregnancy, there is significant risk of miscarriage, premature labour and neurological damage to the fetus.
Professor Eastman, an endocrinologist at the University of Sydney and medical advisor to the Thyroid Foundation warns that, “Pregnant women in Australia are getting about half as much as what they require on a daily basis. 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. In areas where iodine deficiency is severe, IQ scores in children are decreased by 10-15 points, hearing may be impaired, and there is a markedly increased prevalence of attention deficit hyperactivity disorder (ADHD).” The Professor adds that, “It is of serious concern that at least half the babies being born in this country are at risk of suffering some form of mild intellectual impairment as a consequence of maternal iodine deficiency.”
Given the worrying nature of statistics that many pregnant women in New Zealand have an iodine deficiency, women need to be very pro-active in ensuring they are getting enough iodine.
So how can women prevent this condition? Firstly you cannot do it by diet alone. You would need to eat large quantities of food in order to do so. You need an extra 100 – 200 ug of iodine a day during pregnancy. The Food Standards Australia and New Zealand (FSANZ) have implemented the mandatory use of iodised salt in bread in an effort to help increase levels of iodine in food, but this fortification is insufficient.
- drink between half to one litre of milk a day
- use iodised salt. This is not the same as sea salt. You need to check it is the correct one as sea salt is an insufficient source of iodine
- eat food rich in iodine. Seafood and seaweed (such as kelp and nori), is especially high in iodine
- the most useful thing you can do is take iodine supplements, as part of multivitamin supplements. Most contain between 50 – 150 ug of iodine – you need 100 – 200 ug of iodine a day. However it is vital you check your supplements carefully to ensure they do contain iodine as many of the more popular ones do not
In New Zealand, from July 2010, pregnant and breastfeeding women will have access to a new iodine-only tablet (NeuroKare), which will enable them to meet their iodine requirements. NeuroKare contains 150 micrograms of iodine and meets appropriate quality and safety standards – and it is subsidised for pregnant and breastfeeding women. Refer to the Ministry of Health website for more details.
When Caryn checked, she discovered she was taking a supplement that didn’t include iodine and she immediately switched to one that did. In addition, she made some small changes to her diet to incorporate more iodine. For Caryn protecting the development of her baby’s brain was vital and with a little knowledge on the subject she had to tools to do so effectively.