Quick answer

Adults need 150 mcg of iodine a day from all sources, pregnant women 220 mcg and breastfeeding women 290 mcg. Many multivitamins already contain 150 mcg. The upper limit for adults is 1,100 mcg a day, and some iodine-only and kelp supplements go past it in a single dose.^1,2,3,4

Key facts

TSH, the hormone that drives the thyroid, starts to rise when intake falls below about 100 mcg a day.²
Teens aged 14 to 18 have a lower upper limit than adults: 900 mcg a day.²
Babies under a year should get iodine only from breast milk, formula and food.²
In one analysis, supplements made from seaweed or kelp held 5 to 5,600 mcg of iodine per daily dose.⁴

Recommended amounts by age

Recommended iodine per day, from all sources^1,2
Age or stage	Recommended
0 to 6 months	110 mcg
7 to 12 months	130 mcg
1 to 8 years	90 mcg
9 to 13 years	120 mcg
14 years and older	150 mcg
Pregnancy	220 mcg
Breastfeeding	290 mcg

Pregnant women need 220 mcg of iodine a day and breastfeeding women 290 mcg. The World Health Organization recommends 250 mcg a day for both.^1,2

The figures for babies under a year are adequate intakes based on healthy breastfed infants rather than full recommended allowances.²

How much you may already get

In FDA's Total Diet Study, average iodine intake in the US was 216 mcg a day from foods sampled in 2008 to 2012, a figure that leaves out salt added at the table. About 28% to 29% of adults also take a supplement containing iodine.²

Iodized salt in the US contains 45 mcg of iodine per gram, so a quarter teaspoon provides about 78 mcg. Processed foods almost never use iodized salt, and sea salt, kosher salt and Himalayan salt are usually not iodized.^1,2

Bread has much iodine only when it is made with iodate dough conditioners, which about 20% of US bread products list. The iodine in milk varies with farming practices: 59 samples of nonfat milk ranged from 38 to 160 mcg per cup.²

Labels rarely show the iodine that occurs naturally in food, so it is hard to add up your own intake exactly. As a guide, a cup of nonfat milk, a large egg and a quarter teaspoon of iodized salt already come to about 190 mcg, more than an adult's daily need.^1,2

What supplements contain

Of 89 best-selling US adult multivitamins, 74% contained iodine, with a median of 150 mcg per daily serving, all as potassium iodide. Of 59 prenatal vitamins, 34 contained iodine, from 25 to 290 mcg, and about a quarter of those used kelp.³

Products that contain only iodine are a different matter: NIH notes they often hold large amounts, some over the 1,100 mcg limit on their own. Check the micrograms on the Supplement Facts panel, not just whether iodine is listed.²

How much is too much

Upper limit for iodine per day, from all sources^1,2
Age	Upper limit
Under 12 months	Not set; breast milk, formula and food only
1 to 3 years	200 mcg
4 to 8 years	300 mcg
9 to 13 years	600 mcg
14 to 18 years	900 mcg
19 years and older	1,100 mcg

The limits cover iodine from food and supplements combined, but not people taking iodine as a treatment under a doctor's care. Long-term intakes above them raise the risk of thyroid problems, and people with autoimmune thyroid disease may react at lower amounts.²

Questions people ask

Is 1,000 mcg of iodine a day too much?

It is just under the 1,100 mcg adult upper limit but nearly seven times what adults need, and it leaves little room for the iodine in food. Take that much only if a doctor has advised it.²

Should children take iodine supplements?

Children need 90 to 120 mcg a day, which a varied diet with iodized salt usually provides, and their upper limits are low, starting at 200 mcg for ages 1 to 3. Ask a pediatrician before giving any iodine supplement.^1,2

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line

Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.