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Published: 22 May 2013

Discovering the impact of iodine deficiency

New research reveals that iodine deficiency during pregnancy adversely affects children’s mental development.

It’s a vital nutrient, essential for producing the hormones made by the thyroid gland and the development of babies’ brains during early life, yet most people are unaware of the importance of iodine – and the impact deficiency could have on future generations.

Professor Margaret Rayman and Dr Sarah Bath, from the Department of Nutritional Sciences, have published research in The Lancet which reveals that iodine deficiency in pregnancy may have an adverse effect on children’s mental development.  The research raises concerns that the iodine status of pregnant women is a public-health issue that needs to be addressed.

The research was conducted in collaboration with Bristol University and the Avon Longitudinal Study of Parents and Children — a long-term study of more than 14,000 mothers and their families which started in the early 90s — and focused on a group of mothers with mild-to-moderate iodine deficiency during pregnancy and the measure of intelligence quotient (IQ) of their children aged eight. It found that children from women with insufficient levels of iodine (an iodine-creatinine ratio of less than 150 μg/g) were more likely to have scores in the lowest quartile for verbal IQ, reading accuracy and reading comprehension than those from mothers with sufficient levels of iodine (ratios of 150 μg/g or more).

Professor Rayman and Dr Bath have focused on iodine research for several years, working to improve understanding about iodine deficiency in pregnancy, the causes, and the impact that this could have on developing babies in the UK.

Dr Bath, who completed her undergraduate degree in Nutrition and Dietetics at the University of Surrey, was recently awarded a three-year MRC Population Health Scientist Fellowship that will allow her to continue to study iodine nutrition in the UK. Her previous work has included the important discovery that the iodine concentration of organic milk – often favoured by pregnant women – is lower than that of conventional milk. Future projects include looking at ways of assessing pregnant women for iodine deficiency and supplement intervention trials.

Dr Bath said: “I trained as a dietician, so have an interest in translating the information that we get from research into information that pregnant women and the public can use that’s practical and relevant. The requirement for iodine is much higher during pregnancy, so it’s harder to meet from diet alone. At the moment, when you’re pregnant you get no information on iodine, yet that’s the main area of risk and where the most problems arise if you’re deficient.

“The hope is that this might change and people might get more information on iodine, as well as the other nutrients you need during pregnancy.”

The team has put together a website with facts and figures about iodine and information about iodine levels in common foods. An iodine fact sheet, written by Dr Bath and Professor Rayman, is also available.

Read the full press release here.