Chapter 47 - The U-Shaped Curve of Iodine Intake and Thyroid Disorders

Abstract

The association between iodine intake level and the risk of disease is U-shaped, as both low and high iodine intakes are associated with an increase in the risk of thyroid problems. The curve is nonsymmetrical with the most serious problems associated with iodine deficiency, which should be corrected. Both low and high iodine intakes are associated with an increase in the risk of thyroid problems. The most serious problems are associated with iodine deficiency, which should be corrected. However, the iodine intake should only be brought to the level where iodine deficiency disorders are avoided. Optimally, the iodization program should be planned to keep population iodine intake within a relatively narrow range around the recommended level. To compensate for the low iodine supply that was previously highly prevalent in the world, complex mechanisms have been developed in the thyroid gland. Mechanisms are able to accumulate and utilize even very small supplies of iodine. The thyroid immediately reacts to a sudden load of iodine to avoid overproduction of thyroid hormone. As usual when complex mechanisms are involved, this leads to a risk of malfunction—and disease.