Iodine Status in the UK – The Way Forward
A one-day meeting, ‘Iodine Status in the UK – The Way Forward’, was held in June 2012 at the Royal College of Pathology in London and was organised together with the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) and with the British Thyroid Association (BTA). The participants included representatives from ICCIDD, the salt and baking industries, and medical, nutrition and public-health experts.
The meeting concluded that the degree of iodine deficiency in the UK could be adversely affecting pregnancy outcomes and the cognitive development of offspring and that further monitoring of the iodine status in the UK is essential. It called for the development of a national strategy to manage this public health problem.
The meeting was prompted by the results of a survey of more than 700 teenage girls in the UK published in 2011, which found that two-thirds of teenage girls were mild-to-moderately iodine deficient and that a small number had very low levels of iodine1. The study, by BTA researchers led by Dr Mark Vanderpump, was published in the peer-reviewed medical journal The Lancet.
A number of international experts spoke at the meeting. Here are excerpts from some of the presentations:
Professor Michael Zimmerman, Executive Director of ICCIDD (Zurich, Switzerland): two recent randomised controlled trials in children with mild-to-moderate iodine deficiency have shown that iodine treatment significantly improves performance on tests of information processing, fine motor skills, and visual problem-solving.
Professor Margaret Rayman (Surrey, UK): the iodine contribution from food depends on what you consume. Although fish and eggs have the highest concentration of iodine they contribute only 11% and 5% respectively to average UK iodine intake, whereas the high consumption of milk and dairy products accounts for their major contribution to iodine intake, at 38%. Winter milk has a higher iodine concentration than summer milk due to iodine supplements in winter feed. Organic milk has 42% lower iodine content.
Dr Shiao Chan (Birmingham, UK): the iodine requirement in pregnancy is greatly increased compared with the non-pregnant state. There is evidence suggesting that iodine supplementation preferably before conception or early in the first trimester of pregnancy reduces the risk of pregnancy loss, infant mortality, preterm delivery and neurological deficits in women with severe iodine deficiency. However, direct evidence of poor pregnancy outcomes in women with mild-to-moderate iodine deficiency is more limited.
Dr Sarah Bath (Surrey, UK): preliminary results from an unpublished pilot study into the effects of iodine deficiency during pregnancy on offspring development found that children of women deficient in iodine were more likely to have scores in the bottom quartile for total IQ, reading accuracy and Key Stage 2 mathematics score.
Professor Peter Laurberg (Aalborg, Denmark): more than 90% of the population of Denmark was mild or moderately iodine deficient in the 1990s, leading to high prevalence of goitre and thousands of cases of nodular hyperthyroidism each year. A mandatory programme of iodising household and bread salt was started in 2000 which has brought the iodine intake into the recommended range and reduced the incidence of thyroid disease.
Professor Massimo Tonacchera (Pisa, Italy): the iodisation of household salt may not be sufficient to assure adequate iodine nutrition. He gave examples of the potential application of iodine to agricultural soils and iodine fortification of crops. However, further work is needed to develop these.
Ir Wouter Lox (European Salt Producers’ Association, Brussels, Belgium): there are significant challenges to salt producers due to the lack of an effective European public health policy regarding salt iodisation. He called for harmonised action across Europe.
Professor Kate Jolly (Birmingham, UK): there are three main public health strategies for addressing iodine deficiency: population dietary supplementation, supplementation of girls and women before conception, and supplementation during pregnancy. The initial consideration should be a trial of supplementation in early pregnancy.
Following the meeting the UK Iodine Group was established.