Abstract
- Background
Iodine is an essential micronutrient required for the synthesis of thyroid hormones and the maintenance of metabolic, neurodevelopmental, and immune function. Because iodine cannot be synthesized endogenously, adequate intake depends entirely on dietary sources and environmental availability. Despite decades of global progress in improving iodine supply, both iodine deficiency and iodine excess remain significant public health challenges.
- Methods
This review synthesizes current scientific evidence on iodine physiology, including its established role in thyroid hormone biosynthesis and emerging extrathyroidal immunomodulatory and antioxidant functions. It evaluates major dietary sources, global intake patterns, and diagnostic approaches to assess iodine status—such as urinary biomarkers, salivary iodide measurements, and dietary screening tools. Furthermore, it examines clinical outcomes across the spectrum of iodine intake and analyzes public health strategies, including universal salt iodization and targeted supplementation.
- Results
Iodine deficiency continues to cause goiter, hypothyroidism, and impaired neurocognitive development, particularly in vulnerable populations such as pregnant women and infants. Conversely, excessive iodine intake can precipitate iodine-induced thyroid dysfunction, trigger autoimmune thyroid disease, and cause adverse systemic effects. While public health interventions like salt iodization have dramatically improved global iodine sufficiency, emerging salt-reduction initiatives present new policy challenges that threaten long-term stability in iodine intake monitoring.
- Conclusions
Achieving and maintaining optimal iodine intake remains essential for global thyroid health and population well-being. Sustained public health success requires coordinated monitoring, adapted fortification strategies, and updated policy frameworks that balance cardiovascular salt-reduction goals with iodine sufficiency.
https://www.mdpi.com/2072-6643/18/8/1262