Is sea salt a good source of iodine?
Usually not. Specialty salts such as sea salt, kosher salt, Himalayan salt and fleur de sel are not usually iodized, and noniodized sea salt provides almost no iodine. The label says when a salt is iodized.
Trace mineral
Iodine, for your thyroid
Iodine is a trace mineral your thyroid needs to make the hormones thyroxine (T4) and triiodothyronine (T3), which regulate metabolism and are required for normal growth and brain development1.
What iodine does for you.
Thyroid hormones
An essential part of thyroxine (T4) and triiodothyronine (T3), the thyroid hormones1.
Metabolism
Thyroid hormones regulate protein synthesis and enzyme activity and help set metabolic activity1.
Growth & development
Needed for normal bone and brain development in fetuses and infants1.
Steady thyroid
With enough iodine, TSH keeps hormone levels steady; without it the thyroid can enlarge into a goiter1.
Immune response
Iodine appears to play a role in immune response as well1.
How your body uses iodine.
Iodide is quickly and almost completely absorbed in the stomach and duodenum; the thyroid concentrates what it needs and most of the rest leaves in urine1. In thyroid cells the sodium-iodide symporter (NIS) brings iodide in, it is bound to tyrosines on thyroglobulin, and the coupled hormones T4 and T3 are released into the blood3. TSH from the pituitary raises thyroid iodine uptake and hormone release1.
Foods and other sources.
SeaweedCodIodized saltMilkGreek yogurtEggsOystersShrimpCheese
Vegetarian
| Food and serving | Amount |
|---|---|
| Bread, white, made with iodate dough conditioner, 2 slices | 296 µg |
| Seaweed, nori, dried, 2 tbsp flaked (5 g) | 116 µg |
| Yogurt, Greek, plain, nonfat, ¾ cup | 87 µg |
| Milk, nonfat, 1 cup | 84 µg |
| Iodized table salt, ¼ teaspoon | 78 µg |
| Pasta, boiled in water with iodized salt, 1 cup | 30 µg |
| Cheese, cheddar, 1 oz | 14 µg |
Non-vegetarian
| Food and serving | Amount |
|---|---|
| Cod, baked, 3 oz | 146 µg |
| Oysters, cooked, 3 oz | 93 µg |
| Fish sticks, cooked, 3 oz | 57 µg |
| Egg, hard boiled, 1 large | 31 µg |
| Beef liver, cooked, 3 oz | 14 µg |
| Shrimp, cooked, 3 oz | 13 µg |
| Tuna, canned in water, 3 oz | 7 µg |
Iodine in food varies widely: milk depends on cow feed and cleaning agents, only bread made with iodate dough conditioners is rich in it, and seaweeds range enormously1. Amounts per serving from1.
Iodized salt
Many countries iodize table salt, but sea, kosher and Himalayan salts usually are not, and processed foods rarely use iodized salt1.
Supplements
Many multivitamin/mineral products contain iodine; iodine-only products are often high dose1.
Soil and region
Crops from iodine-poor soils, such as mountain areas and flood-prone river valleys, hold less iodine1.
Your daily reference amounts.
The same reference table draws the reference lines on your charts in Ayuvo. Needs differ in pregnancy and breastfeeding, which are not covered here.
| Age | Women | Men | Upper limit |
|---|---|---|---|
| 19–30 | 150 mcg | 150 mcg | 1,100 mcg |
| 31–50 | 150 mcg | 150 mcg | 1,100 mcg |
| 51–70 | 150 mcg | 150 mcg | 1,100 mcg |
| 71+ | 150 mcg | 150 mcg | 1,100 mcg |
RDA (Recommended Dietary Allowance) is the daily amount that meets the needs of nearly all healthy people. Per day, for adults1.
Upper limit (UL) is the most per day that is unlikely to cause harm. Applies to food, drinks and supplements combined.
Too little, too much.
Signs like these have many possible causes. They are a reason to talk to a clinician, not to self-treat.
Too little
Low iodine limits thyroid hormone production; goiter is usually the earliest sign, and deficiency in pregnancy can cause lasting harm to the baby1.
- Goiter (enlarged thyroid)
- Hypothyroidism
- Impaired mental function in adults
- Lower IQ in children
- Harm to fetal development in pregnancy
Too much
High intakes can cause some of the same problems as too little, because excess iodine can block thyroid hormone synthesis in susceptible people1.
- Goiter
- Raised TSH and hypothyroidism
- Iodine-induced hyperthyroidism
- Thyroid inflammation (thyroiditis)
- Burning mouth and stomach at very large doses
- Nausea, vomiting and diarrhea
Urinary iodine (population level).
More than 90% of dietary iodine leaves in urine, so the median urinary iodine of a group reflects its recent intake1. One spot sample varies from day to day, so the WHO cutoffs below describe populations, not individuals; they are based on school-age children and also apply to non-pregnant adults2.
| Median urinary iodine (group) | Population iodine status |
|---|---|
| < 20 µg/L | Severe deficiency |
| 20–49 µg/L | Moderate deficiency |
| 50–99 µg/L | Mild deficiency |
| 100–199 µg/L | Adequate iodine nutrition |
| 200–299 µg/L | Above requirements |
| ≥ 300 µg/L | Excessive; risk of adverse effects |
Labs use different units and ranges. Your clinician reads a result alongside your history and other tests.
Supplement forms.
Iodine in supplements is usually potassium iodide or sodium iodide, and some products use kelp1.
Potassium iodide
Very well absorbed; one small study found about 96% absorption1.
Sodium iodide
Another common form in multivitamin/mineral products1.
Kelp
A seaweed-based source; iodine content varies greatly between seaweeds1.
Iodine-only products
Many contain high doses, sometimes above the upper limit on this page1.
Supplements can interact with medicines. Talk to a clinician or pharmacist before you start one, especially at high doses.
Remember these five.
- Iodine is needed to make the thyroid hormones T4 and T3.
- Seafood, seaweed, dairy, eggs and iodized salt are the main sources; most fruit and vegetables have little.
- Sea, kosher and Himalayan salts are usually not iodized, and processed foods rarely use iodized salt.
- Both too little and too much iodine can disturb thyroid function.
- Urinary iodine describes groups of people; one spot sample says little about one person.
Questions about iodine.
Do vegans get enough iodine?
Seafood, eggs, milk and milk products are among the best sources, so vegans and people who eat few of these foods might not get enough unless they use iodized salt or other iodine sources. Plant milks and most fruit and vegetables contain little iodine.
Do cabbage, broccoli or soy harm the thyroid?
These foods contain goitrogens, which can interfere with iodine uptake by the thyroid. This mainly matters for people who already get too little iodine. For most people who eat a varied diet with enough iodine, reasonable amounts are not a concern.
Get started
Track iodine in Ayuvo.
Food logging does not estimate iodine, so Ayuvo tracks it from supplements you log in Medications, and from Apple Health on iPhone or Health Connect on Android when another app saves it there. Charts by day, week, month and year use the reference lines from this page, personalised by age and sex where they differ. Free, with no account.
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Sources
Facts on this page come from these sources, checked on the dates shown. Intake numbers come from Ayuvo's shared reference table, which cites the sources marked for them.
- Iodine: Fact Sheet for Health Professionals · NIH Office of Dietary Supplements checked 2026-09-27
- Urinary iodine concentrations for determining iodine status in populations (VMNIS, WHO/NMH/NHD/EPG/13.1, 2013) · World Health Organization checked 2026-09-27
- Clinical genetics of defects in thyroid hormone synthesis (Kwak MJ. Annals of Pediatric Endocrinology & Metabolism, 2018) · PubMed Central checked 2026-09-27
General information, not medical advice. This guide is for healthy adults and does not cover pregnancy, breastfeeding, children or medical conditions. It cannot diagnose or treat anything. Talk to a clinician before starting high-dose supplements, or if you think you may have too little or too much of a nutrient. Spotted an error? Email us.
Keep reading.
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