Iodine Deficiency Disorders
Iodine is the raw material the thyroid needs to make hormone. When intake is too low, the thyroid enlarges in an attempt to capture more iodine — producing a goitre — and hormone production can eventually fall.
Iodine deficiency remains an important public health issue in some regions and is particularly harmful during pregnancy and childhood.
Last medically reviewed: 15 November 2025
How deficiency develops
The body cannot make iodine, so it must come from food, water and iodised salt. Where soil and water are low in iodine, and iodised salt is not widely used, deficiency can develop across a whole population.
The thyroid compensates by growing and by working harder, which is why goitre is the classic sign.
Consequences
In adults, iodine deficiency causes goitre and sometimes hypothyroidism. During pregnancy it can impair the baby’s brain development, and in children it can affect growth and cognition.
Severe deficiency has been largely reduced in many countries by iodising salt, but pockets of deficiency persist.
Prevention and treatment
Prevention is straightforward: using iodised salt and eating iodine-rich foods such as dairy, seafood and eggs. In most settings, supplements are unnecessary and excess iodine can itself cause thyroid problems.
Treatment of established deficiency — and of the goitre it causes — depends on the individual, and any iodine supplementation should be guided by a clinician, especially in pregnancy.
Frequently asked questions
Should I take iodine supplements?
Not routinely. In most settings iodised salt provides enough. Excess iodine can cause thyroid problems, so supplements should only be taken on medical advice.
Can iodine deficiency be reversed?
Early goitre often shrinks once iodine intake is corrected, but long-standing changes may persist. Prevention is far better than treatment.
Why does iodine matter in pregnancy?
The baby depends on the mother for iodine to build its own thyroid hormone, which is essential for brain development. Adequate iodine in pregnancy is important.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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