Iodine
What it is and what it does
- Iodine is a trace element found naturally in some foods and added to some types of salt. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- Iodine is an essential part of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- A healthy adult with enough iodine has about 15-20 mg of it, 70-80% of which is in the thyroid. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- The body needs iodine to make thyroid hormones, which control the body's metabolism and many other important functions. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- Thyroid hormones are needed for proper bone and brain development during pregnancy and infancy. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- Thyroid hormones regulate many biochemical reactions, including protein synthesis and enzyme activity, and are critical determinants of metabolic activity. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
Why it matters
- Iodine deficiency has many adverse effects on growth and development. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- Goitre, an enlarged thyroid gland, is often the first visible sign of iodine deficiency. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- In pregnancy, severe iodine deficiency can permanently harm the baby, causing stunted growth, intellectual disability and delayed sexual development. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- ICMR-NIN: iodine from iodised salt is essential for proper brain growth of the baby in the womb and in early infancy. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Too much: high iodine intakes can cause some of the same problems as deficiency, including goitre, raised TSH and hypothyroidism. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
General information, not medical advice — for your own needs, ask a doctor or dietitian.
How much is needed
| Who | Amount | What the figure is | Whose figure |
|---|---|---|---|
| Adult man (all activity levels) | 140 ug/day | RDA | ICMR-NIN 2020 |
| Adult woman (all activity levels) | 140 ug/day | RDA | ICMR-NIN 2020 |
| Pregnant woman | 220 ug/day | RDA | ICMR-NIN 2020 |
| Lactating woman | 280 ug/day | RDA | ICMR-NIN 2020 |
| Adults incl. pregnancy and lactation | 1100 ug/day | TUL (tolerable upper limit) | ICMR-NIN 2020 |
| Adults 19+ years, men and women (US) | 150 ug/day | RDA | US NASEM via NIH ODS (not an Indian value) |
| Pregnancy / breastfeeding (US) | 220 / 290 ug/day | RDA | US NASEM via NIH ODS (not an Indian value) |
| Pregnant women (WHO, UNICEF, ICCIDD) | 250 ug/day | Recommended intake | WHO, UNICEF and ICCIDD, as reported by NIH ODS (not an Indian value) |
| Adults 19+ years, incl. pregnancy and breastfeeding (US) | 1,100 ug/day | UL (tolerable upper intake level) | US NASEM via NIH ODS (not an Indian value) |
India’s own figure (ICMR-NIN 2020) comes first. Figures from other bodies are shown only where they help, and say whose they are.
Sources: ICMR-NIN Expert Group. Short Report of Nutrient Requirements for Indians: Recommended Dietary Allowances and Estimated Average Requirements - 2020; NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05)
Absorption and food
- Iodide is quickly and almost completely absorbed in the stomach and duodenum. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- Some plant foods, including soy and cruciferous vegetables, contain substances that interfere with the way the body uses iodine. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- This interference is a concern mainly for people living in areas prone to iodine deficiency. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- Regions with the most iodine-poor soils include mountain areas such as the Himalayas, and river valleys in South and Southeast Asia. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Consumers (updated 2024-05-01))
- ICMR-NIN advises using iodised salt; its model day's meals use 5 g of iodised salt. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Dairy products contain iodine, though the amount in them varies. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))
- Soils contain varying amounts of iodine, and this affects the iodine content of crops. (NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals (updated 2024-11-05))