Iodine deficiency is often considered a relic of the past, but this is not entirely accurate. During the 20th century, the iodisation of salt emerged as one of the most effective public health interventions, preventing conditions such as goiter and irreversible neurological damage. The World Health Organization still regards iodised salt as a safe and effective strategy, while UNICEF highlights it as the most widely used method to improve iodine intake globally.
However, the success of this measure has pushed iodine out of public discourse. Today, in several countries, signs of insufficient intake are reappearing in certain groups, particularly pregnant or breastfeeding women and those on restrictive diets. This is not a dramatic resurgence of severe symptoms but a silent risk of deficiency where vigilance has waned.
Iodine's Role in the Body
Iodine is essential for synthesising thyroid hormones, which regulate metabolism, growth, and physiological processes. Adequate intake during pregnancy and early childhood is critical for central nervous system development and brain maturation. Needs increase during pregnancy and breastfeeding due to heightened hormone production, renal excretion, and transfer to the fetus or infant.
Why Deficiency Is on the Rise Again
The issue is not reduced salt consumption but a shift in salt types and dietary sources. Iodised salt has been replaced by gourmet or natural salts like sea salt, pink Himalayan salt, flaked salt, and kosher salt, often perceived as healthier but not necessarily iodised. Iodised salt suffers from an image problem, viewed as ordinary compared to its trendy rivals.
Additionally, much sodium now comes from processed and ultraprocessed foods, where iodised salt use is not guaranteed. The WHO has called for coordination between sodium reduction policies and iodised salt promotion. Dietary changes also play a role: iodine is naturally present in seafood, dairy, and eggs, but levels vary. When people reduce these sources without consuming iodised salt or fortified foods, deficiency risk increases.
Plant-Based Diets
Vegetarian and vegan diets can be healthy but require attention to iodine. A 2023 review in the British Journal of Nutrition found that people on plant-based diets, especially vegans, may struggle to meet iodine recommendations from food alone. The solution is straightforward: just as vitamin B12 is recommended for those reducing fish or dairy, iodine should be considered.
Pregnancy and Breastfeeding
Iodine deserves special attention during pregnancy. Severe deficiency can affect fetal development and thyroid function. The US National Institutes of Health considers a urinary concentration of 150–249 micrograms per liter adequate for pregnant women. While concerns about mild or moderate deficiency are legitimate, evidence on cognitive benefits of supplementation is inconclusive. Nonetheless, the American Thyroid Association recommends 150 μg of iodine daily in prenatal supplements for women planning conception, pregnant, or breastfeeding.
Why 'More Salt' Is Not the Answer
Advocating for iodised salt does not mean higher salt intake. The WHO recommends reducing sodium to prevent hypertension and cardiovascular disease. The solution is less salt, but what we consume should be iodised. The WHO emphasises that reducing salt and fortifying with iodine are compatible if concentrations are adjusted and industry salt is fortified. This avoids the pitfalls of defending table salt or assuming sodium reduction solves all health issues. Striking a balance between preventing cardiovascular disease and iodine deficiency is possible.
