The thyroid gland incorporates iodine into the hormones triiodothyronine (T3) and thyroxine (T4), which regulate metabolism, growth, and development. Adults need approximately 150 mcg/day; pregnancy and breastfeeding increase requirements significantly (220 mcg and 290 mcg respectively).
Iodine deficiency remains a global public health concern. In India, the National Iodine Deficiency Disorders Control Programme mandates iodisation of all edible salt — one of the most cost-effective public health interventions ever implemented. Before widespread iodisation, endemic goitre (enlargement of the thyroid gland in response to low iodine) was widespread in inland and hilly regions.
Dietary sources: iodised salt is the most reliable for most Indians. Seafood (fish, prawns, seaweed) and dairy are other significant sources; the iodine content of plant foods depends entirely on soil iodine levels and is unpredictable.
A critical counterpoint: excess iodine — from supplements, kelp powder, or seaweed — can also trigger thyroid dysfunction, including both hypothyroidism and hyperthyroidism, particularly in people with pre-existing thyroid conditions or Hashimoto’s thyroiditis. More is not better. If you have a thyroid condition, discuss iodine supplementation with your clinician before taking it.