October 2024

While it’s not a recognized official event, World Iodine Deficiency Prevention Day, celebrated on October 21 every year, has grown organically so that it is now used in countries around the world to raise awareness of the critical role iodine plays in public health and in safeguarding learning capability in children.  For us at IGN, it’s a time to remember that continued iodization of salt helps us to achieve a world without iodine deficiency.

At the World Iodine Association International Conference on Iodine in Food Systems in Health earlier this month, IGN and WHO presented the newly published report on prevention and control of iodine deficiency in Europe.  Presentations reflected on the fact that the more visible signs of iodine deficiency – goiters, severe mental retardation, and other health disorders were widespread in the region and others, such as the United States, a century ago.  Thankfully, these have largely been eliminated – not just in these countries, but globally – by the public health campaign to iodize household salt in the 1990s.

But the fact that the outwards signs of iodine deficiency have disappeared may mask a re-emerging problem.  The report points out that changes in diet and lifestyle – a shift to the use of processed foods rather than cooking in the home; a move away from dairy products (which contain iodine) to milk and meat substitutes (which may not); the popularity of vegan diets – may all be eroding iodine status, as most of these foods don’t contain iodine.

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The report raises another concern – where salt iodization is mandatory, the population is generally iodine sufficient.  But there are still countries in Europe and around the world where this is not the case.  This problem is compounded by the fact that routine iodine status surveillance using nationally representative population-based studies is lacking in most European counties.  This is also true globally, with data so old that we may no longer know the true situation.  This is borne out by a couple of recent surveys (Sri Lanka and Bhutan) which show re-emergence of iodine deficiency.

While the outward signs of iodine deficiency have not returned, the damage caused even by mild deficiency is significant, both economically in terms of health care costs. Moderately low iodine levels, particularly in early pregnancy, may be associated with lower verbal IQ in children[i], and there is evidence that moderate deficiency negatively impairs children’s cognitive functions[ii].

The more rapidly a country can assess both iodine status and salt consumption, the quicker they can act to prevent iodine deficiency.  IGN, in partnership with the Bill & Melinda Gates Foundation and UNICEF, are developing tools to quickly and cost-effectively assess population iodine status through a sentinel site methodology, and to help countries understand whether or not their iodine program is optimal.

With such knowledge and interventions, a problem that is totally preventable can remain that way.  On World Iodine Deficiency Day, that is our hope for the future.

[i] Levie D, Korevaar TIM, Bath SC, Murcia M, Dineva M, Llop S, Espada M, van Herwaarden AE, de Rijke YB, Ibarluzea JM, Sunyer J, Tiemeier H, Rayman MP, Guxens M, Peeters RP. Association of Maternal Iodine Status With Child IQ: A Meta-Analysis of Individual Participant Data. J Clin Endocrinol Metab. 2019 Dec 1;104(12):5957-5967. doi: 10.1210/jc.2018-02559. PMID: 30920622; PMCID: PMC6804415

[ii] Bailote HB, Linhares D, Carvalho C, Prazeres S, Rodrigues AS, Garcia P. Iodine Intake and Related Cognitive Function Impairments in Elementary Schoolchildren. Biology (Basel). 2022 Oct 14;11(10):1507. doi: 10.3390/biology11101507. PMID: 36290411; PMCID: PMC9599038