UK population deficient in iodine

12 April 2011

The UK population could be iodine-deficient according to a study presented today at the Society for Endocrinology annual conference. Iodine deficiency can affect brain development and result in lower IQ.

The study concludes that a full review and evidence-based recommendations are needed to safeguard public health.

The findings provide the only current data on the UK’s iodine status and demonstrate iodine-deficiency in a large sample population. Iodine-deficiency is the most common cause of preventable mental impairment worldwide.

In the study, which was funded by the Clinical Endocrinology Trust and is the first of its kind in the UK, Dr Mark Vanderpump of the Royal Free Hampstead NHS Trust and colleagues measured urinary iodine levels in samples from 737 14-15 year old girls from nine UK centres.

The median urinary iodine level in participants was 80μg/L, making the group ‘deficient’ by World Health Organisation standards (defined as below 100μg/L). 69% of the samples were in this deficient category (below 100ug/L) and 18% of samples showed very low iodine levels below 50μg/L.

As this was a relatively small audit study that was confined to a single age group and sex, a full-scale investigation into the iodine status of the entire UK population is now warranted to see whether public health bodies need to implement any health measures.

Iodine is an essential trace element that helps the thyroid gland function properly. Most people get their iodine from their diet. Iodine-deficiency is the most common cause of preventable mental impairment worldwide and accordingly, the World Health Organisation has conducted a global programme of salt iodisation since 1993. The UK is yet to join this programme and does not require salt producers to iodise their salt.

Young women of childbearing age are the most susceptible to the adverse effects of iodine-deficiency and even mild deficiency may have an impact on the developing brain of foetuses and young children. It can also cause goitre. According to the World Health Organisation, iodine-deficient communities have IQs up to 13.5 points lower than similar but iodine-sufficient communities.

Researcher Dr Mark Vanderpump, Consultant Physician and Honorary Senior Lecturer in Diabetes and Endocrinology at the Royal Free Hampstead NHS Trust said: “Our data suggest the UK is now iodine deficient, warranting a full investigation of the UK iodine status. We need to look into this now to decide whether public health bodies need to step in.

“The World Health Organisation has made iodine-deficiency a global priority and has been campaigning for at-risk countries to add iodine to their salt, a campaign which has been very successful. If it turns out that we do have a problem, this could be the most viable solution.

“We are very concerned about these findings as the consequences of iodine-deficiency are grave: iodine-deficient communities score lower in IQ tests, and even mild iodine-deficiency during pregnancy can cause serious mental impairments in children.”