Iodine

Why do we study iodine intake?

• Iodine is an essential micronutrient and a key component of the thyroid hormone, which is an important regulator of many metabolic processes. By extension, iodine plays an important role in modulating the basal metabolic rate, regulating body temperature, and in growth, neurodevelopment and cognitive function. 
• Iodine is found in two forms in food: iodide (I-) and iodate (IO3-). It is naturally present in both animal and plant sources like dairy, fish, eggs, and grains and grain products and fortified salt. 
• Because iodine deficiency is a public health issue, also in Belgium, table salt is fortified to improve the iodine status of the population. Iodised salt is recommended by the Belgian Superior Health Council to be used as a replacement for regular table salt, as an additional source of iodine. It is, however, not recommended to consume additional salt to improve iodine status, because of the negative consequences of excessive salt intake.
• Especially among pregnant and breastfeeding women, and young children, iodine deficiency is a common nutritional concern. Insufficient iodine intake can lead to iodine deficiency disorders, causing impaired cognitive and physical development in children, and fatigue, mental slowing, weight gain and metabolic disorders in adults. The Belgian Superior Health Council states that a healthy and varied diet, opting for iodised salt and products produced with iodized salt, such as bread, provides enough iodine.
• Although iodine deficiency is a widespread issue, especially in pregnant and breastfeeding women, it is important to note that excessive intake of iodine, particularly through supplements, can have adverse effects, such as thyroid disorders, like goiter. Monitoring intake is essential to ensure a balance between sufficiency and safety.

How do we study it?

• The prevalence of inadequate iodine intake from food only, and food and supplements combined was estimated as the proportion of individuals with an habitual iodine intake below the reference values set by the European Food Safety Authority (EFSA): 90 µg/day for children, 120 to 130 µg/day for adolescents, depending on age and 150 µg/day for adults 18 years and above.
• The prevalence of excessive iodine intake is calculated by comparing the intake of iodine from food and from food and supplements to the reference values set by EFSA established by health authorities. between 200 and 300 µg/day for children depending on age, between 450 and 500 µg/day for adolescents depending on age, and 600 µg/day for adults 18 years and above.
• Habitual intake of iodine was analysed using the SPADE® program. A detailed description of the methodology for deriving the habitual iodine intake, the type of reference values used and the age-and-sex-specific values of these references can be found here.
• Due to statistical limitations, the results of iodine cannot be presented by educational level or region.
• Only intake of iodine present in foods was able to be assessed, but not intake of iodine from the use of iodised salt added during cooking or at the table. Therefore, the results shown for iodine are an underestimation of the real intake.