Mild iodine deficiency in pregnancy may harm your baby’s IQ, say scientists

Women should eat more iodine-rich food in the early stages of pregnancy, suggest scientists, who've linked iodine deficiency with poorer IQ scores for the baby-to-be


More mums-to-be are becoming mild to moderately deficient in iodine – and it’s possible this could end up having a negative effect on our baby’s IQ.


So say UK scientists, who, in separate studies, have found that two-thirds of pregnant women now have a mild to moderate iodine deficiency – and that children of women who are more iodine-deficient when they’re pregnant are more likely to score poorly for verbal IQ, reading accuracy and reading comprehension at the age 8 and 9.

The researchers, from the Universities of Surrey and Bristol, say that their study demonstrates the importance of adequate iodine intake during early pregnancy. They say that the results “emphasise the risk that iodine deficiency can pose to the developing infant, even in a country [such as the UK, that is] classified as only mildly iodine deficient”.

Further studies have been conducted by the University of Glasgow who have found that women in the UK are not aware of how important iodine is during pregnancy. Dr Emilie Combet, who led the research says, “Women aren’t receiving the message about the importance of iodine in pregnancy, meaning they cannot make informed choices to ensure they get the amount they require.

 “Iodine is crucial during pregnancy and the first months of life, to ensure adequate brain development, but achieving over 200ug a day of iodine through diet requires regular consumption of iodine-rich foods such as milk and sea fish. Not everyone will have the knowledge, means or opportunity to achieve this.

“There is an ongoing debate as to whether there should be some form of fortification of food with iodine. Iodine-fortified salt is common in other countries, but using salt as the delivery method has raised concerns since it is perceived to clash with public health messaging around reducing salt intake to combat high blood pressure. However, other countries have demonstrated that both measures could be held simultaneously. We need to work toward a solution.”

So do I need to take iodine supplements if I’m pregnant?

Recent research by Kate Jolly at the University of Birmingham has speculated that it might be a good idea for pregnant women to take an iodine supplement, however, the study remains inconclusive as there has been no actual research into the impact of giving an iodine supplement to women who are only mildly deficient. 

Dr Louis Levy, head of nutrition science, diet and obesity, at Public Health England (PHE), thinks it’s unnecessary: “The longstanding government advice is that everyone including pregnant women should be able to get all the iodine they need from a varied and balanced diet.” 

Iodine is essential for growth and development of the brain, and pregnant women need 50 per cent more (250mcg) than women who are not pregnant (150 mcg). But you should still be able to get enough iodine from the food you eat.

The best food sources of iodine are milk, yoghurt and fish. Conventional milk contains more iodine than organic milk, and white fish more than oily fish.

So, if you’re pregnant and you eat 2 portions of fish a week and 3 portions of dairy products a day, your iodine intake should be fine.

If you have an allergy to dairy or fish (or just plain don’t like them), then take a regular pregnancy supplement, checking the label first to make sure it contains iodine (all reputable pregnancy supplements should).

It is important not to have too much iodine: more than 600mcgs a day can cause thyroid problems. In particular, it’s wise to avoid kelp and seaweed supplements when you’re pregnant, as they can contain excessive amounts of iodine.

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