The thyroid gland requires
iodine to synthesize
thyroid hormones, and
iodine deficiency results in the inadequate production of
thyroxine and related thyroid, metabolic, developmental, and reproductive disorders.
Iodine requirements are higher in infants, children, and during pregnancy and lactation than in adult men and non-pregnant women.
Iodine is available in a wide range of foods and water and is susceptible to almost complete gastric and duodenal absorption as an
iodide ion. A healthy diet usually provides a daily
iodine consumption not exceeding 50% of the recommended intake.
Iodine supplementation is usually necessary to prevent
iodine deficiency disorders (IDDs), especially in endemic areas. The community-based strategy of
iodine fortification in
salt has eradicated IDDs, such as
endemic goiter and
cretinism, in countries providing adequate measures of
iodine prophylaxis over several decades in the 20th century.
Iodized salt is the cornerstone of
iodine prophylaxis in endemic areas, and the continuous monitoring of community
iodine intake and its related clinical outcomes is essential. Despite the relevant improvement in clinical outcomes, subclinical
iodine deficiency persists even in Western Europe, especially among girls and women, being an issue in certain physiological conditions, such as pregnancy and lactation, and in people consuming unbalanced vegetable-based or
salt-restricted diets. Detailed strategies to implement
iodine intake (supplementation) could be considered for specific population groups when
iodized salt alone is insufficient to provide adequate requirements.