PUBLIC HEALTH
IODINE: COMBATTING DEFICIENCY Charlie Cooke Nutritionist and Personal Trainer Nutritionist Charlie Cooke focuses on teaching simple nutrition science, boxing fitness and nutritious home-cooking knowledge to the general/ low-income public. He is now pursuing a writing, reviewing and media career. Charlie runs the website www. knowhownutrition. co.uk/
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Iodine is most probably something that you’re not losing regular sleep over. But, as iodine deficiency is one of the top three public health problems worldwide, affecting two billion people and 245 million school-age children, and being the leading preventable cause of brain damage and mental development issues worldwide (WHO, 2007),1 it perhaps should surely have been eradicated by now. Since 1990, the International Council for Control of Iodine Deficiency Disorder’s (ICCIDD - try saying it 10 times really fast) proposal on Iodine Deficiency Disorders (IDD), as imposed by the United Nations summit in 1992, has been working to make global IDD a distant memory. Yet, the only distant memory is the date which the UN had planned to achieve its target. We are almost two decades away from the year 2000 and, despite 12 countries moving their iodine status to optimal and an overall reduction in iodine deficiency in school-aged children by 5% (among other advances), the UK hasn’t quite seen such gleaming developments, as outlined by Vanderpump and colleagues in 2011, who found 51% of school-age girls to be mildly deficient and 16% to be moderately so.2 CRITIQUE OF METHODS
The typical method of assessing iodine status is by median urinary iodine (UI) levels in school-age children. This is a very easy method, with Vanderpump et al2 being able to assess over 700 samples, though the median must be used in lieu of the mean, due to the large amounts of individual variability. Not only that, but UI levels represent the 90% of iodine consumed because, you guessed it, 90% is excreted. This does mean, however, that we are only measuring the most recent levels of iodine consumption and most especially not measuring levels of thyroid function. Nevertheless, this method followed a similar structure to that used by the WHO in their global assessments and correlates with the guideline methods established by Dr Michael Zimmerman of 44
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the ICCIDD,3 though preferably bloodspot thyroglobulin would be used. WHAT ARE THE RISKS OF IDD?
The very same Dr Zimmerman (2009)4 found that those iodine deficient children suffered an IQ score of 10-15 points lower than their optimally iodised counterparts. This trend has been concordantly correlated in 37 different studies in China, finding an average deficiency of 10 IQ points and thus further correlated by a meta-analysis of another 18 studies demonstrating an average difference of 13.5 IQ points. Reading and writing is hard enough, we need all the help we can get. In the more severe cases of deficiency, more prices are to be paid. Goitre is an excessive enlargement of the thyroid gland which is essentially the processing centre for about 70-80% of our iodine to form the crucially important T3 and T4 hormones. When our iodine levels are at the point of deficiency, the thyroid is no longer able to function properly and is, therefore, underactive (hypothyroidism). If untreated, this condition may progress to a large growth. A foetus is at risk of cretinism when a mother is unable to meet her minimum requirement of iodine during pregnancy. Cretinism is a state of severe mental and developmental retardation due to iodine’s dramatically large role in tissue synthesis (modulation of gene transcription by heterodimerisation with RXR 9-cis-retinoic acid), especially in the brain, spinal cord, liver, kidneys and alike. There are two forms of cretinism: