Nutrition

Iodine-Rich Foods: The Best Sources and How Much You Need

The foods richest in iodine, ranked by a realistic serving, with numbers from the federal iodine database, how much you need at every stage of life and how to keep your thyroid supplied without overdoing it.

By Dr. Josh Axe, DC, DNM, CNS·20-min read

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Evidence-based40 sources citedUpdated October 8, 2026

Published Oct 8, 2026Last updated Oct 8, 2026Editorial policyMedical review policyFact-checking policy

Seaweed, fish and eggs, three of the iodine sources on this list.

Iodine-rich foods at a glance

The richest everyday sources of iodine are wild white fish such as cod and haddock, sea vegetables such as nori, plain yogurt and milk, iodized salt and pasture-raised eggs, and most adults need 150 micrograms (mcg) a day.1 2

Three ounces of baked cod carries 146.3 mcg, 2 tablespoons of flaked nori 115.8, a cup of whole milk 81.8 and a hard-boiled egg 30.51
I recommend getting your iodine from food, mainly wild fish, eggs and sea vegetables in gentle amounts, and keeping it to normal amounts, not megadoses3
Unrefined sea salt carries minerals and almost no iodine, so in a kitchen that uses it, your iodine comes from the foods on this list1 4
Selenium is iodine's partner in making active thyroid hormone, and my protocol supplies it with one to two Brazil nuts a day5 3

Iodine is the mineral your thyroid builds its hormones from, and your body can't make any of it, so every microgram has to come from what you eat and drink. The element was discovered in seaweed. In 1811, a French chemist treating seaweed ash with acid watched a violet vapor rise from it, and the new element took its name from the Greek word for violet.6

Iodine collects mostly in coastal soils and the sea, which is why seaweed and other seafood are its most common natural sources, while milk picks it up on the farm.6 The list below ranks the best iodine-rich foods by the iodine in a realistic serving, using the federal iodine database, along with how much you need at each stage of life and who should be careful with it.1

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My approach to iodine is the one in my Hypothyroidism Protocol: get it from food, in normal amounts.3

Some of the best iodine-rich foods include sea vegetables, wild fish and eggs. If your thyroid antibodies are high, keep doses moderate.Dr. Josh Axe, DC, DNM, CNSWritten in The Hypothyroidism Protocol (2026), p. 13

What does iodine do in your body?

Quick answer

Your thyroid uses iodine to make its two hormones, T4 and T3, which help regulate your metabolism.6 When iodine runs too low, the gland can't make enough hormone, which can lead to an underactive thyroid and a goiter, an enlarged thyroid gland.7

In my Hypothyroidism Protocol, I describe the thyroid as the body's thermostat: when it's turned down, every room in the house goes cold.3 Iodine is one of the raw materials that keeps it running, alongside tyrosine, selenium, iron and zinc.3 Here's how the iodine on your plate becomes thyroid hormone:

1Iodide reaches your blood

Nearly all the iodine in milk is already iodide, and your body absorbs it well.8

2Your thyroid pulls it in

Thyroid cells take up iodide from the blood avidly, through a dedicated pump called the sodium/iodide symporter.9

3Iodine meets tyrosine

The enzyme thyroid peroxidase attaches iodine to tyrosine units on thyroglobulin, the protein the gland builds its hormones on.9

4Mostly T4 leaves the gland

About 80% of the hormone the gland makes is T4, the storage form.3

5Selenium makes the active form

Selenium-dependent enzymes called deiodinases turn T4 into T3, the active hormone your cells respond to.5

6A large load puts on the brake

A big dose of iodine briefly slows hormone making, for about a day in the original animal studies (the Wolff–Chaikoff effect). Most people adapt, while people with thyroid disease, including autoimmune thyroiditis, may not.10

That last step is the reason the goal is enough iodine, steadily, from food. And iodine is only one input. On my show, I put it plainly: "The thyroid is just the messenger."11 By the time symptoms show up, the real causes sit upstream, and as my protocol explains, most low-thyroid cases involve three or four of them working together, such as stress, gut health, blood sugar and missing nutrients, so iodine works best as part of the whole picture.3

Enough iodine also matters for a growing brain. In a placebo-controlled trial of 184 mildly iodine-deficient New Zealand children aged 10 to 13, in which neither the children nor the researchers knew who got what, a daily 150 mcg iodine tablet for 28 weeks raised median urinary iodine to 145 mcg/L, against 81 on placebo. It improved two of four reasoning tests, picture concepts and matrix reasoning, with no difference on the other two, and lifted their overall cognitive score above the placebo group's.12 A review that pooled two such trials in school-age children found the same kind of gain in perceptual reasoning, plus a gain in overall cognition.13

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How much iodine do you need a day?

Quick answer

Adults and teens 14 and older need 150 mcg of iodine a day, pregnant women 220 mcg and breastfeeding women 290 mcg.2 The upper limit for adults is 1,100 mcg a day from food, water and supplements combined.2

These are the Recommended Dietary Allowances from the Institute of Medicine, with adequate intakes for babies, whose needs come from breast milk or formula.2

Life stage	Daily need (mcg)	Upper limit (mcg)
Babies, birth to 6 months	110 (adequate intake)	Not set
Babies, 7 to 12 months	130 (adequate intake)	Not set
Children, 1 to 3 years	90	200
Children, 4 to 8 years	90	300
Children, 9 to 13 years	120	600
Teens, 14 to 18 years	150	900
Adults, 19 and older	150	1,100
Pregnancy	220	1,100 (900 under age 19)
Breastfeeding	290	1,100 (900 under age 19)

A day with two hard-boiled eggs, ¾ cup of whole-milk Greek yogurt and 2 tablespoons of nori comes to about 249 mcg, adding up the database values.1

Which foods are highest in iodine?

Quick answer

Lean white ocean fish lead the list: 4 ounces of raw haddock carries 249.7 mcg and 3 ounces of baked cod 146.3.1 Dried nori, milk, plain yogurt, iodized salt, cottage cheese and eggs follow.1

Every number here comes from the USDA, FDA and NIH Iodine Database (Release 4.0, 2024), which measured foods sold across the U.S. and reports each one per serving.1 The last column shows how much of an adult's 150 mcg a serving covers.

Food	Serving	Iodine (mcg)	Share of an adult's daily need
Haddock, raw	4 oz	249.7	166%
Cod, baked	3 oz	146.3	98%
Nori, dried	2 tbsp, flaked (5 g)	115.8	77%
Whole milk	1 cup	81.8	55%
Iodized table salt	¼ tsp	78.2	52%
Greek yogurt, whole milk, plain	¾ cup	71.9	48%
Iodized sea salt	¼ tsp	70.0	47%
Plain yogurt, whole milk	¾ cup	55.0	37%
Cottage cheese, full fat	½ cup	50.3	34%
Pollock, raw	4 oz	47.9	32%
Eggs, scrambled with oil	½ cup	46.8	31%
Swiss cheese	1 oz	41.2	27%
Egg, hard-boiled	1 large	30.5	20%
Wild pink salmon, raw	4 oz	28.8	19%
Wild sockeye salmon, raw	4 oz	20.2	13%
Sea salt, non-iodized	¼ tsp	0.02	0%

Natural foods vary from sample to sample. The 28 samples of baked cod ranged from 74.8 to 280.5 mcg per serving, and the haddock, nori and pollock figures each come from 3 samples, so read each number as a typical amount.1 Fruits, vegetables, grains and beans carry little iodine, because plants take up only what's in the soil and water where they grow.10

The best iodine-rich foods, ranked

My order follows the iodine in a realistic serving, and within dairy I put the fermented foods first, because the best dairy is the lacto-fermented kind.4 Each card's badge grades the human research showing that the food raises iodine levels in people.

Wild white fish: cod and haddock

Moderate evidenceHuman studyRandomized trial of 133 pregnant women, 122 finished · 28 samples of baked cod

Lean, white-fleshed ocean fish carry the most iodine per serving on this list. Three ounces of baked cod averages 146.3 mcg, nearly a full day's need, and 4 ounces of raw haddock measured 249.7 in the database's 3 samples. Pollock, another white fish, carries 47.9 mcg in 4 ounces raw.1

Cod has been tested as a food. In a randomized trial in Norway, 133 pregnant women in a group with mild-to-moderate iodine deficiency were assigned either to eat 200 grams (about 7 ounces) of cod twice a week for 16 weeks or to keep their usual diet. Among the 122 who finished, median urinary iodine was 98 mcg/L in the cod group and 73 in the comparison group, and their thyroid hormone levels didn't differ.14 For the babies, mothers in the cod group reported fewer social and emotional problems at 3 and 6 months; at 11 months, the babies scored no differently on two of three development scales and lower on the third, the cognitive scale.15 14

My Hypothyroidism Protocol lists wild salmon, sardines and cod among its eat-freely foods.3 Choose wild, ocean-caught fish with fins and scales, the standard Jordan Rubin and I lay out in The Biblio Diet.4 Bake, broil or poach the fillet, and see the best fish to eat for more choices.

Sea vegetables, in gentle amounts: nori, dulse and kelp

Emerging evidenceHuman studyStudy of 42 women, no comparison group · absorption test in 22

Seaweed was easing goiters thousands of years before anyone knew iodine existed. Chinese medical writings from about 3600 B.C. are the first on record to describe goiters shrinking after people ate seaweed, and Hippocrates and Galen later wrote about the same remedies.6 My Hypothyroidism Protocol ranks sea vegetables third among its top 10 thyroid foods: kelp, nori and dulse give whole-food iodine and tyrosine, the building blocks of the hormone, in gentle amounts.3

Two tablespoons of flaked dried nori carries 115.8 mcg, the average of the database's 3 samples.1 Kelp and its relatives vary far more, from one species and harvest to the next, which is why the amounts stay small.16

In a 2-week study of 42 British women who ate little dairy or seafood, with no comparison group, half a gram of encapsulated whole seaweed a day raised their median urinary iodine from 78 to 140 mcg/L; their TSH rose from 1.5 to 2.1 mIU/L, and two women went just above the normal range while their free T4 stayed normal.17 The researchers found the seaweed palatable and effective as an iodine source; in their absorption test of 22 women, about 33% of its iodine was absorbed (59% from a potassium iodide pill).17 In a study of 20 young Chinese adults split between a kombu meal and potassium iodide, 18 of whom finished, 23.7% to 29.5% of the kombu's iodine was absorbed, against 63.7% to 83.5% of the iodide.18 The kombu's iodine came through in a gradual rise where the iodide's surged, and the researchers suggest kombu as an alternative to iodized salt.18

Use sea vegetables in seasoning amounts: a sheet of nori wrapped around fish and vegetables, a pinch of dulse flakes over eggs, a small strip of kombu in a pot of soup. If you have a thyroid condition, check the safety section before adding them.

Half a gram of seaweed a day: iodine up from 78 to 140

Source: Combet et al. · British Journal of Nutrition, 2014 [17]Median urinary iodine before and after the 2 weeks of seaweed.

Yogurt, kefir and milk

Moderate evidenceHuman studyAbsorption study of 12 adults, 11 finished, each tried all three drinks · study of 111 U.S. adults

Milk gets its iodine on the farm, from the iodine given to the cows and the iodine-based cleansers used on their teats and on milk cans.6 1 A cup of whole milk carries 81.8 mcg, ¾ cup of plain whole-milk Greek yogurt 71.9, ½ cup of full-fat cottage cheese 50.3 and an ounce of Swiss cheese 41.2.1 Kefir hasn't been measured in the iodine database yet. Farming practices matter: the 59 whole-milk samples ranged from 41.5 to 204.5 mcg per cup.1

That iodine is well absorbed. In a Swiss study of 12 adults, 11 of whom finished, each drank three test drinks in random order: milk naturally high in iodine, low-iodine milk with iodide added and iodide in water. The amount of iodine they excreted didn't differ among the three, and 80% to 93% of the milk's iodine was in the form of iodide.8 In a study of 111 young U.S. adults who collected their urine for 24 hours and reported what they ate, dairy was the strongest dietary predictor of their iodine levels.19

The best dairy is the lacto-fermented kind: yogurt, kefir, hard cheeses and cottage cheese, ideally full-fat and A2.4 I steer people away from conventional dairy, so choose plain, full-fat yogurt or kefir, from A2 cows or from goat milk, when you can.3

Iodized salt

Strong evidenceHuman studyU.S. population records since 1924 · review of salt iodization

Iodized salt greatly reduced iodine deficiency in the United States a century ago.20 Before the 1920s, 26% to 70% of children in the "goiter belt" of the Great Lakes, Appalachian and Northwestern states had visible goiter. Iodized salt reached grocery shelves in Michigan on May 1, 1924, and the country's iodine status improved significantly through that decade.6 Worldwide, carefully monitored salt iodization is considered the best way to prevent iodine deficiency in most countries.21

A quarter teaspoon of iodized table salt carries 78.2 mcg, and the same amount of iodized sea salt 70.0.1 Iodization in the U.S. is voluntary, and when 88 brands of table salt were sampled, 47 contained less iodine than the FDA's recommended range. Most of the salt Americans eat comes in processed foods, which are made primarily with non-iodized salt.6 The next section covers how unrefined sea salt fits in.

Pasture-raised eggs

Emerging evidenceHuman studyStudy of 111 U.S. adults · 35 samples of hard-boiled eggs

One hard-boiled egg carries 30.5 mcg of iodine, and nearly all of it sits in the yolk: a quarter cup of frozen liquid yolk measured 107.9 mcg, against 0.9 for the same amount of egg white.1 In the same 24-hour urine study of 111 young U.S. adults, egg intake was the second dietary predictor of iodine levels, after dairy.19

My Hashimoto's Protocol puts pasture-raised eggs among its top 10 thyroid foods at 2 to 3 a day, for their selenium, iodine in normal amounts and choline, and my Hypothyroidism Protocol calls them the most digestible tyrosine there is.22 3 Three hard-boiled eggs come to about 92 mcg, a little over half of an adult's day, adding up the database values.1 Eat the whole egg, yolk included.

Shellfish are left off this list on purpose. For seafood, I hold to the standard in The Biblio Diet: wild, ocean-caught fish with fins and scales, and cod, haddock, pollock and salmon all qualify.4 See fish you should never eat for the full skip list.

Wild salmon carries modest iodine, 28.8 mcg in 4 ounces of raw wild pink salmon and 20.2 in wild sockeye, several times the 3.6 mcg in the same amount of farmed Atlantic salmon.1 My Hypothyroidism Protocol ranks wild salmon and sardines second among its thyroid foods for their omega-3s, vitamin D and selenium.3

Iodine in a typical serving of the top sources

Source: USDA ARS, FDA and NIH ODS · Iodine Database Release 4.0, 2024 [1]Adults need 150 mcg a day.

Here's how to put the list to work this week:

Eat wild white fish twice a week. Three ounces of baked cod averages 146.3 mcg, and the Norwegian trial used two 7-ounce cod meals a week.1 14
Season with sea vegetables. A sheet of nori, a pinch of dulse flakes or a small strip of kombu is enough; 2 tablespoons of flaked nori carries 115.8 mcg.1
Choose plain, full-fat fermented dairy. Three-quarters of a cup of whole-milk Greek yogurt carries 71.9 mcg.1
Eat the whole egg. Nearly all of a hard-boiled egg's 30.5 mcg sits in the yolk.1
Add one to two Brazil nuts a day for the selenium your body uses to turn T4 into active T3.3 5
Read your supplement labels. Most top-selling adult multivitamins already carry iodine, usually 150 mcg, so count it before adding more.28

Does sea salt have iodine?

Quick answer

Unrefined sea salt has almost no iodine: a quarter teaspoon of non-iodized sea salt carries 0.02 mcg, compared with 78.2 mcg in iodized table salt and 70.0 in iodized sea salt.1 Pink Himalayan salt hasn't been measured in the federal iodine database.1

I recommend salt on real food. My advice on the show is not to go crazy with it, but to sprinkle a quality sea salt or Himalayan salt on your food regularly.23 The Biblio Diet, my book with Jordan Rubin, explains that salts differ in their mineral makeup, and that unrefined sea salt carries minerals such as calcium, magnesium and potassium, with no additives.4 Table salt is about 97.5% sodium chloride and 2.5% additives, and the book counts the added iodine among them: generally well tolerated, though it could cause thyroid dysfunction in people who are more sensitive to its effects.4 See unrefined sea salts for more on how they're made.

Unrefined salt seasons your food without adding iodine, so in a kitchen that uses it, your iodine comes from the fish, sea vegetables, dairy and eggs above.1 If those foods rarely make it onto your plate, iodized salt is the dependable fallback.

Planning your iodine for the week?

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Is iodine deficiency coming back?

Quick answer

Mild shortfalls are becoming more common in the U.S., especially among women of childbearing age: in national survey data, their median urinary iodine fell from 135.0 mcg/L in 2001–2002 to 103.5 in 2017–2020.24

That analysis covered 6,828 women aged 14 to 45 in the National Health and Nutrition Examination Survey (NHANES), and the share below 100 mcg/L, the World Health Organization's cutoff for adequate iodine in a population of nonpregnant women, rose from 37.6% to 47.7%.24 A second NHANES analysis of 22,851 people aged 14 and older found that the share of women and girls 14 and older falling below the average iodine requirement doubled, from 12% in 2001–2002 to 24% in 2017–2018, and in 2017–2018, 46% of pregnant women fell below it.25 A 2025 review of U.S. studies named the main reason: people are drinking less milk.20

U.S. women's iodine levels have slipped

Source: Cheng et al. · BMC Pregnancy and Childbirth, 2025 [24]The share of women below 100 mcg/L rose from 37.6% to 47.7%.

Urinary iodine works as a population yardstick. One person's level swings with what they ate the day before, so a single urine test can't tell you whether you're low.6 The people most likely to run short are easy to name:

Little or no dairy, fish or eggs: These are the main whole-food sources on the list above, and national survey researchers single out women who don't consume dairy as a group that may be at risk.26
Vegans and vegetarians: In a review of 15 studies with 127,094 adults, vegans had the lowest iodine levels, followed by vegetarians, and omnivores had the highest intakes in 83% of the studies.27 See the vegan diet for planning help.
Pregnancy and breastfeeding: Needs climb to 220 and 290 mcg a day, and the section below covers them.2

How much iodine do you need during pregnancy?

Quick answer

Pregnant women need 220 mcg of iodine a day and breastfeeding women 290 mcg, compared with 150 for other adults.2 The American Thyroid Association recommends a daily supplement with 150 mcg for women who are pregnant, breastfeeding or planning a pregnancy; confirm the dose with your OB.28 40

Dr. Will Cole and I include iodine in the table of key nutrients for women in Heal Your Cells: it's essential for thyroid function, especially during pregnancy, and mild deficiencies are common and can affect fetal development.29

In a UK study that followed 1,040 mothers and their children, children whose mothers had low iodine early in pregnancy (below 150 mcg per gram of creatinine) had about 1.5 to 1.7 times the odds of scoring in the lowest quarter for verbal IQ at age 8 and for reading at age 9.30 A later pooled analysis of 6,180 mother-child pairs from three cohorts, including that one, found a smaller effect: verbal and nonverbal IQ averaged 0.6 points lower below 150 mcg per gram, differences too small to rule out chance, and the link with verbal IQ appeared only in the first 14 weeks of pregnancy.31

A 2020 review of 37 studies, including 10 randomized trials, found that iodine supplements in mildly deficient pregnant women lowered the mothers' thyroglobulin in most of those trials and, in three, prevented or limited the growth of the mothers' thyroid during pregnancy; pooling the two trials that tested the children found no difference in their cognitive, language or motor scores.32

Food helps here too. In the randomized Norwegian cod trial above, two 7-ounce cod meals a week raised pregnant women's iodine levels.14 Prenatal vitamins differ: of 59 top-selling U.S. prenatal vitamins, 57.6% contained iodine, usually 150 mcg, and about a quarter of those that did used kelp as the source.28 Check your label. If you have Hashimoto's, have your thyroid and antibodies checked before and early in pregnancy, because needs change quickly.22

Why does selenium matter for iodine?

Iodine builds thyroid hormone, and selenium turns it into the active form. The deiodinase enzymes that convert T4 to T3 depend on selenium, and the thyroid holds onto its selenium more tightly than most tissues, which is why extra selenium in healthy people hasn't shown clear effects on thyroid hormone levels.5 On my show, I've called selenium one of the most critical nutrients for thyroid function. With Hashimoto's, I've said to be careful about how much iodine you take and to calm the autoimmune reaction first with nutrients like selenium.11

Brazil nuts top my Hypothyroidism Protocol's list of thyroid foods at one to two a day, and my Hashimoto's Protocol adds a reminder not to overdo it.3 22 The research on selenium in Hashimoto's is encouraging. A 2024 review of 35 randomized trials found that selenium supplements lowered TPO antibodies, the marker of the immune attack on the gland, with a large effect across 2,358 patients, and lowered TSH in people not taking thyroid hormone, with side effects no different from the comparison groups; free T4 and T3 didn't change.33 In an earlier placebo-controlled trial of 70 women with autoimmune thyroiditis, 200 mcg of selenium a day for 3 months brought antibodies down to 63.6% of where they started, against 88% on placebo, and 9 women on selenium reached normal antibody levels, against 2 on placebo.34

Brazil nuts deliver it in food form, though the amount varies from nut to nut. In a 12-week randomized trial of 59 New Zealand adults, two nuts a day supplied about 53 mcg of selenium on average, anywhere from 20 to 84 mcg depending on the nuts, and raised plasma selenium 64.2%, as much as a 100 mcg selenium supplement (61.0%), compared with 7.6% on placebo.35 For more food sources, see selenium foods.

Do cruciferous vegetables block iodine?

Cooked cruciferous vegetables are fine; only very large amounts of raw greens or juices are worth limiting.22 In a 4-week study of 10 volunteers with no comparison group, adding 150 grams (about 5 ounces) of cooked Brussels sprouts a day caused no change in TSH, T4 or T3.36 Raw crucifers carry glucosinolates, and some of them break down into compounds that can interfere with the thyroid; the researchers credit cooking, which inactivates the plant enzyme myrosinase that starts that breakdown.36

That's why I recommend cooking your crucifers, which deactivates their goitrogens. Broccoli and cabbage stay on my top 10 thyroid foods for the sulforaphane they supply; the habit to drop is the large raw cruciferous smoothie.3

Should you take an iodine supplement?

Carefully. I recommend getting your iodine from food, because high-dose iodine can worsen Hashimoto's, and testing your thyroid before you supplement.3 Food brings iodine along with the other materials your thyroid uses, such as tyrosine in eggs and sea vegetables and selenium in Brazil nuts and wild fish.3 Check your multivitamin before you add anything, too: in a study of top-selling U.S. products, 74.2% of 89 adult multivitamins contained iodine, usually 150 mcg a day.28 If you're pregnant or planning a pregnancy, the pregnancy section above covers supplements.

A thyroid panel tells you more about your thyroid than a urine iodine test. Ask your doctor for TSH, free T4, free T3 and TPO antibodies, the markers my protocol reads against functional ranges.3 6

Four thyroid markers worth knowing

These tests show how your thyroid is working and whether autoimmunity is part of the picture, and no single result diagnoses a thyroid condition on its own.

TSH: The pituitary's signal to your thyroid. It rises when the thyroid is underactive.
Free T4: The main hormone your thyroid releases, the raw material for T3.
Free T3: The active thyroid hormone, made mostly by selenium-dependent enzymes.
TPO antibodies: The antibodies that mark autoimmune (Hashimoto's) thyroiditis.

See the cellular bloodwork panel

Have results? Analyze them free → →

Who should be careful with iodine?

Quick answer

Iodine above the daily need is generally well tolerated, but people with Hashimoto's or another thyroid condition, older adults, unborn and newborn babies, and people taking amiodarone or lithium are more likely to react to large amounts.10 Adults should stay under 1,100 mcg a day from all sources.2

Your thyroid works best in a middle range. A Chinese study followed 3,018 adults for 5 years in three regions with different iodine intakes. New cases of subclinical hypothyroidism, a raised TSH with normal thyroid hormone, ran 0.2% where intake was mildly low (median urinary iodine 84 mcg/L), 2.6% where it was more than adequate (243) and 2.9% where it was excessive (651), and autoimmune thyroiditis followed the same pattern, at 0.2%, 1.0% and 1.3%.37 The study compared regions rather than assigning intakes. A major review of iodine deficiency concludes that the relatively small risks of too much iodine are far outweighed by the risks of too little, and that's why the goal is enough.21

Take extra care with iodine if any of these apply:

Hashimoto's and other thyroid conditions: Get your iodine from food, and avoid kelp and high-dose iodine unless your doctor has tested you and advised it, because too much can worsen autoimmunity.22 Kelp's iodine varies enormously: in a lab analysis of 12 seaweeds, iodine ran from 16 mcg per gram in nori to more than 8,165 mcg per gram in one sample of kelp granules sold as a salt substitute, and some seaweed dishes may pass the 1,100 mcg adult upper limit.16 Case reports describe an overactive thyroid in one woman who drank kelp tea for 4 weeks and in another patient who took kelp supplements for years.10 Small doses of iodine pills matter too: when 40 people with Hashimoto's in Germany took 250 mcg of potassium iodide a day for about 4 months, 9 developed thyroid dysfunction, mostly subclinical hypothyroidism, compared with 1 of 43 similar patients who took none, and 4 of them returned to normal after stopping.38
Thyroid medication: Keep taking it exactly as prescribed, on an empty stomach and at least four hours apart from iron, calcium and fiber supplements.22 Keep it apart from milk too: in 10 healthy adults who each took levothyroxine with and without 12 ounces of 2% milk, the milk lowered how much of the hormone reached the blood.39
Amiodarone and lithium: Amiodarone, a heart-rhythm drug, is rich in iodine, and lithium raises the risk of iodine-related thyroid problems.6 10 If you take either, check with the prescribing doctor before adding seaweed or an iodine supplement.
Pregnancy, newborns and older adults: These groups are less able to adapt to large iodine loads.10 In pregnancy, aim for the 220 mcg target.2

The bottom line

Why food is the best way to get your iodine

Your thyroid needs a steady, modest supply of iodine, and a handful of everyday foods cover it: a fillet of wild cod or haddock, a little nori or dulse, a bowl of plain yogurt or kefir, a couple of pasture-raised eggs. Those same foods bring the selenium, tyrosine and protein your thyroid uses alongside iodine, which is why I want your iodine coming from food.3 To me, seaweed's long record against goiter deserves real weight.6

Build your week around wild fish, a little sea vegetable, fermented dairy and pasture-raised eggs, add one to two Brazil nuts a day, and season with unrefined sea salt. The free Hypothyroidism Protocol turns these foods into a week of thyroid-supportive meals, and if you have recent labs, analyze your bloodwork free →

Give your thyroid what it was built to run on, a little iodine from real food every day, and it can keep every room in the house warm.

Iodine-rich foods: frequently asked questions

What foods are highest in iodine?

Lean white ocean fish: 4 ounces of raw haddock carries 249.7 mcg and 3 ounces of baked cod 146.3.1 Dried nori, milk, plain yogurt, iodized salt, cottage cheese and eggs follow.1

How much iodine do you need a day?

Adults and teens 14 and older need 150 mcg a day, pregnant women 220 and breastfeeding women 290.2 The adult upper limit is 1,100 mcg a day from all sources.2

Does sea salt have iodine?

Almost none: a quarter teaspoon of non-iodized sea salt carries 0.02 mcg, while the same amount of iodized sea salt carries 70.0.1 With unrefined salt, your iodine comes from fish, sea vegetables, dairy and eggs.

Is iodized salt a good source of iodine?

Yes: a quarter teaspoon supplies 78.2 mcg, and iodized salt's arrival in the 1920s significantly improved iodine status in the United States.1 6 I recommend sprinkling a quality sea salt on real food and getting your iodine from foods.23 3 When fish, sea vegetables, dairy and eggs are rare in a diet, iodized salt is the dependable fallback.

Do eggs have iodine?

Yes. One hard-boiled egg carries 30.5 mcg, about a fifth of an adult's daily need, and nearly all of it is in the yolk.1 My Hashimoto's Protocol includes pasture-raised eggs at 2 to 3 a day.22

Does milk have iodine?

Yes. A cup of whole milk averages 81.8 mcg, though samples ranged from 41.5 to 204.5, and ¾ cup of plain whole-milk Greek yogurt carries 71.9.1 I recommend fermented, full-fat dairy such as yogurt and kefir.4

Which fish has the most iodine?

Haddock and cod: 4 ounces of raw haddock measured 249.7 mcg and 3 ounces of baked cod 146.3.1 Pollock follows with 47.9 mcg in 4 ounces raw.1

Does salmon have iodine?

Yes, in modest amounts: 4 ounces of raw wild pink salmon carries 28.8 mcg and wild sockeye 20.2, several times the 3.6 in farmed Atlantic salmon.1 My Hypothyroidism Protocol ranks wild salmon and sardines second among its thyroid foods for their omega-3s, vitamin D and selenium.3

Is seaweed good for your thyroid?

In gentle amounts, yes: kelp, nori and dulse give whole-food iodine and tyrosine, and my Hypothyroidism Protocol ranks sea vegetables third among its thyroid foods.3 In 42 women who ate little dairy or seafood, half a gram of seaweed a day for 2 weeks raised median urinary iodine from 78 to 140 mcg/L, in a study with no comparison group.17 With a thyroid condition, check the safety section before adding seaweed.

Can vegans get enough iodine?

It's harder: in a review of 15 studies, vegans had the lowest iodine levels of any diet group.27 Sea vegetables in gentle amounts are the main plant source, since fruits, vegetables and grains carry little.3 10

Do cruciferous vegetables block iodine?

Not when they're cooked: cooked cruciferous vegetables are fine, and only very large amounts of raw greens or juices are worth limiting.22 In a small study of 10 volunteers with no comparison group, 150 grams of cooked Brussels sprouts a day for 4 weeks didn't change TSH, T4 or T3.36

Should I take an iodine supplement?

Carefully. I recommend getting iodine from food, because high-dose iodine can worsen Hashimoto's, and testing your thyroid status before you supplement.3 In pregnancy, the American Thyroid Association recommends a daily supplement with 150 mcg; confirm the dose with your OB.28

How much iodine do you need when pregnant?

220 mcg a day, and 290 mcg while breastfeeding.2 The American Thyroid Association recommends a daily supplement with 150 mcg; confirm the dose with your OB.28

Can you get too much iodine from food?

From everyday foods it's uncommon, since the adult upper limit is 1,100 mcg a day and a serving of baked cod carries 146.3.2 1 Seaweed is the food to keep to gentle amounts, and the safety section lists the people who should take the most care.

Is iodine good for Hashimoto's?

In food amounts, yes: iodine is essential, and with Hashimoto's it should come from food without megadosing, because high doses can worsen autoimmunity.22 3 The safety section has the details.

What are the signs of low iodine?

The classic sign is a goiter, an enlarged thyroid, and low iodine can also leave the thyroid underactive.7 An underactive thyroid can show up as fatigue that sleep doesn't fix, feeling cold, weight gain, hair thinning, dry skin, constipation and brain fog, and a thyroid panel confirms it.3 See iodine deficiency for more.

Freshness & method note

October 5, 2026 — Rewrote the page in Dr. Axe's voice around his food-first approach to iodine, replacing the 2024 version by Jillian Levy. Food values now come from the USDA, FDA and NIH Iodine Database (Release 4.0, 2024). Corrected the seaweed figure the earlier page listed as "up to 2,984 mcg" per kelp sheet (published analyses report iodine per gram, from 16 in nori to more than 8,165 in one kelp product), and removed iodine values for lima beans, prunes, corn and wakame that the current database doesn't support. Removed shellfish, which Dr. Axe doesn't recommend, and uncited claims about deficiency rates, cancer and sweating out toxins. Added a ranked list with study evidence for each food, the full intake and upper-limit table, three charts, a diagram of how your thyroid uses iodine, sections on salt, pregnancy, selenium, cruciferous vegetables and supplements, one safety section and an FAQ, with 39 numbered references.

October 6, 2026 (second update) — Replaced the pull-quote with Dr. Axe's own wording and rewrote his other quoted lines as complete sentences (the "messenger" line, the selenium line, the thermostat line and the at-a-glance food line). Kept iodized salt in fact voice in the FAQ, and added The Biblio Diet's note that table salt counts iodine among its additives. Added the measured 20 to 84 mcg range for two Brazil nuts, a six-step "put the list to work" checklist from figures already on the page, the scrambled-egg label as the database lists it ("with oil"), and the American Thyroid Association's 2017 pregnancy guideline as reference 40. Read time corrected to the body length. Simplified the UK pregnancy study's odds to a range (about 1.5 to 1.7 times), split the pregnancy evidence paragraph, and trimmed the closing phrase from the Hashimoto's pregnancy line.

October 7, 2026 — Per Dr. Axe's Oct 7 ruling, strawberries are out of the pull-quote's list of iodine-rich foods (the Iodine Database lists 0.4 mcg per ¾ cup), and the quote's source line now names his Hypothyroidism Protocol directly.

References

Dr. Josh Axe, DC, DNM, CNS

Doctor of Natural Medicine · Founder, DrAxe.com

Dr. Axe is a certified doctor of natural medicine, clinical nutritionist, and multiple New York Times bestselling author. He has spent 20+ years in clinical practice helping people heal at the root cause and founded one of the most-visited natural-health platforms in the world.

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This article is for educational purposes. See our medical disclaimer.