Iodine
Also known as I, Iodide
Iodine is an essential trace mineral that the thyroid gland uses to make thyroid hormones, which regulate metabolism and are critical for brain and skeletal development, especially during pregnancy and infancy. Iodine deficiency remains a leading preventable cause of intellectual disability worldwide. Iodized salt and dairy are major dietary sources. Requirements are set as an RDA in micrograms and rise sharply during pregnancy.
The recommended intake sits at about 14% of the level considered the safe daily ceiling, leaving comfortable headroom.
Why it matters
What it does in your body
- Synthesis of thyroid hormones
- Regulation of metabolism
- Fetal and infant brain development
- Normal growth and skeletal development
- Nervous system function
By age, sex, and life stage
How much you need
Iodine uses an RDA for children and adults (AI for infants 0 to 12 months). The adult requirement is 150 mcg for both sexes. Pregnancy raises it sharply to 220 mcg and lactation to 290 mcg to protect fetal and infant brain development.
Recommended intake across life
in mcg/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Infants 0-6 mo | 110 (AI) | 110 (AI) |
| Infants 7-12 mo | 130 (AI) | 130 (AI) |
| Children 1-3 | 90 | 90 |
| Children 4-8 | 90 | 90 |
| Children 9-13 | 120 | 120 |
| Teens 14-18 | 150 | 150 |
| Adults 19+ | 150 | 150 |
| Pregnancy | n/a | 220 |
| Lactation | n/a | 290 |
Values in mcg/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Age
Needs rise from 90 mcg in young children to 150 mcg by the teen years and stay there through adulthood.
Sex
No difference between adult men and women; both need 150 mcg.
Body weight / size
Adult requirements are set equally for both sexes; childhood values scale with growth.
Pregnancy and lactation
Pregnancy jumps to 220 mcg and lactation to 290 mcg because iodine is vital for fetal brain development and is passed through breast milk.
Diet type
Vegans and people who avoid iodized salt, seafood, and dairy are at higher risk of falling short.
Running low
Signs you might not get enough
Most at risk: Pregnant women, vegans and people who avoid seafood and dairy, those who use non-iodized salt, and people living in regions with iodine-poor soil are at higher risk.
Too much
Can you get too much?
Both excess and deficiency can paradoxically cause goiter and thyroid dysfunction. People with autoimmune thyroid disease are especially sensitive to high iodine intakes.
Where to get it
Best food sources
The bottom line
Iodine is small in quantity but enormous in impact, especially for a developing brain, so pregnant and breastfeeding women need substantially more. Iodized salt and dairy make deficiency rare in many countries, but vegans and salt-avoiders should watch their intake. Seaweed can deliver wildly excessive amounts, so use it in moderation.
Track iodine automatically
Iodine is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- NIH Office of Dietary Supplements, Iodine Fact Sheet for Health Professionals
- Institute of Medicine (IOM/NASEM), Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.