Abstract
Iodine is a micronutrient that is essential for thyroid hormone production. Adequate iodine intake is especially important during pregnancy and early life, when brain development is dependent on thyroid hormones. Iodine intake recommendations vary around the world, but most recommendations generally reflect the increased requirements during pregnancy and lactation, although adequate iodine intake prior to pregnancy is also important. Tremendous progress has been made in improving iodine intake across the world over the past 30 years, mainly through salt iodisation programmes. However, in countries without strong iodine fortification programmes, and with shifts in dietary patterns, a need has arisen for health organisations, governments and clinicians to ensure adequate iodine is consumed by everyone in the population. For example, in countries where adequate iodine intake depends on individual food choice, particularly of iodine-rich milk and dairy products, intake can be highly variable and also vulnerable to changing dietary patterns. In this Review, iodine is considered in the wider context of the increasing prevalence of overweight and obesity, the dietary trends for salt restriction for cardiovascular health, and the increasing uptake of plant-based diets.