How much iodine do I need?
The amount of iodine you need each day depends on your age. Average daily recommended amounts are listed below in micrograms (mcg).
| Life Stage | Recommended Amount |
|---|---|
| Birth to 6 months | 110 mcg |
| Infants 7-12 months | 130 mcg |
| Children 1-8 years | 90 mcg |
| Children 9-13 years | 120 mcg |
| Teens 14-18 years | 150 mcg |
| Adults | 150 mcg |
| Pregnant teens and women | 220 mcg |
| Breastfeeding teens and women | 290 mcg |
Sources from supplements come as potassium iodide or sodium iodide. Many multivitamin-mineral supplements contain iodine. Dietary supplements of iodine-containing kelp (a seaweed) are also available.
Am I getting enough iodine?
Most people in the United States get enough iodine from foods and beverages. However, certain groups of people are more likely than others to have trouble getting enough iodine:
- People who do not use iodized salt. Adding iodine to salt is the most widely used strategy to control iodine deficiency. Currently, about 70% of households worldwide use iodized salt.
- Pregnant women. Women who are pregnant need about 50% more iodine than other women to provide enough iodine for their baby. Surveys show that many pregnant women in the United States may not get quite enough iodine, although experts do not know whether this affects their babies.
- People living in regions with iodine-deficient soils who eat mostly local foods. These soils produce crops that have low iodine levels. Among the regions with the most iodine-poor soil are mountainous areas, such as the Himalayas, the Alps, and the Andes regions, as well as river valleys in South and Southeast Asia.
- People who get marginal amounts of iodine and who also eat foods containing goitrogens. Goitrogens are substances that interfere with the way the body uses iodine. They are present in some plant foods including soy, and cruciferous vegetables such as cabbage, broccoli, cauliflower and brussels sprouts. For most people in the United States who get adequate amounts of iodine, eating reasonable amounts of foods containing goitrogens is not a concern.
What happens if I don’t get enough iodine?
Iodine deficiency is uncommon in the United States and Canada. People who don’t get enough iodine cannot make sufficient amounts of thyroid hormone. This can cause many problems. In pregnant women, severe iodine deficiency can permanently harm the fetus by causing stunted growth, mental retardation, and delayed sexual development. Less severe iodine deficiency can cause lower-than-average IQ in infants and children and decrease adults’ ability to work and think clearly. Goiter, an enlarged thyroid gland, is often the first visible sign of iodine deficiency.
What are some effects of iodine on health?
Scientists are studying iodine to understand how it affects health. Here are some examples of what this research has shown.
Fetal and infant development
Women who are pregnant or breastfeeding need to get enough iodine for their babies to grow and develop properly. Breastfed infants get iodine from breast milk. However, the iodine content of breast milk depends on how much iodine the mother gets.
To make adequate amounts of iodine available for proper fetal and infant development, several national and international groups recommend that pregnant and breastfeeding women and infants take iodine supplements. In the United States and Canada, the American Thyroid Association recommends that pregnant and breastfeeding women take prenatal vitamin/mineral supplements containing iodine (150 mcg/day). However, only about half the prenatal multivitamins sold in the United States contain iodine.
Cognitive function during childhood
Severe iodine deficiency during childhood has harmful effects on the development of the brain and nervous system. The effects of mild iodine deficiency during childhood are more difficult to measure, but mild iodine deficiency might cause subtle problems with neurological development.
Giving iodine supplements to children with mild iodine deficiency improves their reasoning abilities and overall cognitive function. In children living in iodine-deficient areas, iodine supplements seem to improve both physical and mental development. More study is needed to fully understand the effects of mild iodine deficiency and of iodine supplements on cognitive function.
Fibrocystic breast disease
Although not harmful, fibrocystic breast disease causes lumpy, painful breasts. It mainly affects women of reproductive age but can also occur during menopause. Very high doses of iodine supplements might reduce the pain and other symptoms of fibrocystic breast disease, but more study is necessary to confirm this. Check with your healthcare provider before taking iodine for this condition, especially because iodine can be unsafe at high doses.
Radiation-induced thyroid cancer
Nuclear accidents can release radioactive iodine into the environment, increasing the risk of thyroid cancer in people who are exposed to the radioactive iodine, especially children. People with iodine deficiency who are exposed to radioactive iodine are especially at risk of developing thyroid cancer. The U.S. Food and Drug Administration has approved potassium iodide as a thyroid-blocking agent to reduce the risk of thyroid cancer in radiation emergencies.
