Research

Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)

BMJ 2007; 334 doi: https://doi.org/10.1136/bmj.39147.604896.55 (Published 26 April 2007) Cite this as: BMJ 2007;334:885

Re: Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)

Iodine status in the UK – the way forward

Concern that iodine deficiency may now be widespread in the UK prompted a meeting of medical, nutrition and public-health experts, and representatives from the salt and baking industries. The meeting, on the 29th June 2012 in London, was organised by the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) with the British Thyroid Association and the British Thyroid Foundation.
Last year, the first UK national survey for over 60 years to assess iodine status was reported in the Lancet.1 The median urinary iodine concentration (80.1µg/L) in the cohort of teenage schoolgirls was indicative of mild iodine deficiency and, based on this UK-wide survey, the UK now finds itself among the top ten iodine-deficient countries worldwide in terms of numbers of iodine-deficient school-age children.2
Currently the UK does not have a policy of salt iodisation, the primary method worldwide for the eradication of iodine deficiency and provision of adequate iodine to the population. Therefore a concerted effort is required by a multidisciplinary group to ensure that the risk of iodine deficiency is minimised in the UK.

The meeting, which was called to discuss the problem as well as potential solutions and strategies, included presentations from a range of experts and was followed by a panel discussion. It was noted that randomised placebo-controlled trials in children from areas of mild-to-moderate iodine deficiency have shown improvements in cognitive scores3,4 and that preliminary results from a UK birth-cohort study showed that children of women deficient in iodine were more likely to have scores in the bottom quartile for total IQ, reading accuracy and mathematics5. It is therefore likely that the degree of iodine deficiency prevalent in the UK could be adversely affecting pregnancy outcomes and child cognitive development, although high-quality trial evidence in the UK population is currently lacking.

The meeting also included presentations on UK sources of iodine, alternative methods of optimising iodine prophylaxis, public-health approaches that could be utilised in the UK and lessons that have been learnt from other European countries that have successfully implemented programmes to improve iodine status in their populations.

Further monitoring of UK iodine status is essential to provide documentation of its extent and identify the prevalence of the adverse effects of iodine deficiency. The meeting concluded with the unanimous recommendation that a national strategy be developed to manage this public health problem.

1. Vanderpump MP, Lazarus JH, Smyth PP, et al. Iodine status of UK schoolgirls: a cross-sectional survey. Lancet 2011; 377: 2007-2012.
2. Andersson M, Karumbunathan V, Zimmermann MB. Global Iodine Status in 2011 and Trends over the Past Decade. J Nutr 2012; 142: 744-750.
3. Gordon RC, Rose MC, Skeaff SA, Gray AR, Morgan KM, Ruffman T. Iodine supplementation improves cognition in mildly iodine-deficient children. Am J Clin Nutr 2009; 90: 1264-1271.
4. Zimmermann MB, Connolly K, Bozo M, Bridson J, Rohner F, Grimci L. Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study. Am J Clin Nutr 2006; 83: 108-114.
5. Bath S, Steer C, Golding J, Emmett P, Rayman MP. Maternal iodine status during pregnancy and the impact on cognitive outcomes in the offspring. Proc Nutr Soc 2011; 70: OCE6, E386.

The authors confirm that they have no no support from any organisation for the submitted work ; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years , no other relationships or activities that could appear to have influenced the submitted work

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Competing interests: No competing interests

20 August 2012
John H Lazarus
Prof Clinical Endocrinology
Sarah Bath, Kate Jolly, Margaret Rayman, Mark Vanderpump, Graham Williams, Michael Zimmermann
Cardiff University
University Hospital of Wales, Heath Park, Cardiff