Iodized salt prevents iodine deficiency by adding a small amount of iodine to table salt

Iodized salt is regular salt with iodine added during processing — typically potassium iodide or sodium iodide at a concentration of about 45 micrograms per gram of salt. One teaspoon of iodized salt contains roughly 150 to 200 micrograms of iodine, which is close to the daily amount most adults need. The iodine is stable in the salt for several years if stored in a cool, dry place away from moisture and light.

Your body cannot make iodine on its own. You need it to produce thyroid hormones, which control your metabolism, body temperature, heart rate, and how your brain develops. Without enough iodine, your thyroid gland enlarges (a condition called goiter), your metabolism slows, you may gain weight, and in severe cases during pregnancy or infancy, iodine deficiency can cause permanent brain damage. Iodized salt was introduced in the 1920s specifically to stop these problems, and it has been remarkably effective — iodine deficiency is now rare in countries where iodized salt is widely used.

Key Takeaways

  • Iodized salt contains about 150 to 200 micrograms of iodine per teaspoon, meeting most adults' daily iodine needs in a small amount.
  • Your thyroid needs iodine to make hormones that control metabolism, energy, and brain development.
  • Most people in the United States get enough iodine from iodized salt, but some groups — including people who eat very little salt, follow certain diets, or live in areas with low-iodine soil — may not.
  • Sea salt, kosher salt, and specialty salts are usually not iodized unless the label says otherwise, so switching to them without another iodine source can leave you short.
  • Iodine from salt is absorbed well by your body and remains stable in the salt for years if stored properly.

How much iodine you actually need

The recommended dietary allowance (RDA) for iodine is 150 micrograms per day for most adults, 220 micrograms for pregnant people, and 290 micrograms for people who are breastfeeding. Children need less — 90 micrograms for ages 1 to 3, and 120 micrograms for ages 4 to 8. One teaspoon of iodized salt covers most of the daily need for an adult, so you do not need much to stay above deficiency.

The challenge is that most people do not measure their salt intake by the teaspoon. A typical American diet contains 3,000 to 5,000 milligrams of sodium per day, which comes from processed foods, restaurant meals, and home cooking — far more than the recommended 2,300 milligrams. If that salt is iodized, you are likely getting enough iodine without thinking about it. If you eat very little salt, follow a low-sodium diet for health reasons, or use non-iodized salt exclusively, you may fall short.

Who is most likely to be low in iodine

People who eat processed foods and restaurant meals regularly almost always get enough iodine from iodized salt in those foods. People at higher risk of iodine deficiency include those who cook almost entirely from scratch using non-iodized salt, follow a strict low-sodium diet, avoid dairy and eggs (which contain iodine), eat mostly plant foods grown in iodine-poor soil, or live in regions where soil iodine is naturally low — parts of the Midwest, Great Lakes region, and Pacific Northwest fall into this category.

Pregnant people and those planning pregnancy should pay attention to iodine intake, because iodine deficiency during pregnancy increases the risk of miscarriage, stillbirth, and developmental delays in the child. Vegans and vegetarians who do not eat dairy, eggs, or seaweed may need to track iodine more carefully, since animal products and seaweed are the most concentrated food sources. People taking certain medications, including some thyroid drugs and lithium, may have altered iodine absorption and should discuss this with their doctor.

Iodized salt versus other salt types

Table salt is almost always iodized in the United States unless the label says otherwise. Sea salt, kosher salt, Himalayan pink salt, and specialty finishing salts are usually not iodized — the iodine is not added during processing. If you switch to these salts for taste or texture, you lose the iodine benefit unless you find a brand that specifically adds it. Check the label: if iodine is not listed in the ingredients, the salt does not contain it.

Some people avoid iodized salt because they believe iodine causes health problems or because they prefer the taste of non-iodized varieties. The amount of iodine in iodized salt is safe for the vast majority of people. Very high iodine intake can cause problems in people with existing thyroid disease, but the amount in table salt is not high enough to cause this in healthy people. If you prefer non-iodized salt, you can get iodine from other sources: dairy products, eggs, fish, seaweed, and iodine supplements.

How to store iodized salt so it keeps its iodine

Iodine in salt is volatile — it evaporates when exposed to air, moisture, or light. To preserve the iodine content, store iodized salt in an airtight container in a cool, dry place away from direct sunlight. A sealed shaker with a moisture-absorbing packet works well. Do not store it near the stove or in a humid bathroom, and do not leave the container open between uses.

Under proper storage conditions, iodine in salt remains stable for at least three to five years. Once you open the container, the iodine content begins to decline, but it takes months of regular use before the loss becomes significant. If you buy iodized salt and store it poorly — in a humid kitchen, in an open dish, or in direct sunlight — you may lose most of the iodine within weeks. Check the expiration date on the package if one is printed, though this is more about salt quality than iodine loss.

Other reliable sources of iodine

If you do not use iodized salt, you can get iodine from food. Dairy products contain iodine because cows eat iodine-containing feed and iodine is used in some milking processes. Eggs are another reliable source. Fish and shellfish contain iodine, though the amount varies depending on the iodine content of the water where they were caught. Seaweed is extremely high in iodine — sometimes too high — so it should not be your only source. Cranberries, prunes, and lima beans contain moderate amounts if they were grown in iodine-rich soil.

Iodine supplements are available as potassium iodide tablets, iodine drops, or as part of a multivitamin. A typical supplement contains 150 micrograms, matching the RDA. Supplements are useful if you avoid iodized salt and do not eat much dairy, eggs, or fish. Talk to your doctor before starting an iodine supplement if you have thyroid disease, take thyroid medication, or live in an area where iodine deficiency is not common — too much iodine can cause problems in people with certain thyroid conditions.

Signs you might not be getting enough iodine

Mild iodine deficiency often causes no obvious symptoms, which is why it can go unnoticed. As deficiency worsens, you may notice fatigue, weight gain, dry skin, hair loss, difficulty concentrating, or a slow heart rate. Your thyroid gland may enlarge, creating a visible swelling in the neck (goiter). These symptoms are not specific to iodine deficiency — they can come from many causes — so the only way to know is a blood test.

If you suspect iodine deficiency, ask your doctor for a thyroid-stimulating hormone (TSH) test or a urine iodine test. A TSH test measures how hard your pituitary gland is working to stimulate your thyroid, which rises when iodine is low. A urine iodine test directly measures iodine status. These tests are straightforward and can tell you whether you need to change your salt use or add another iodine source.

Frequently Asked Questions

Does iodized salt raise blood pressure more than regular salt?

No. Iodized salt and non-iodized salt have the same sodium content and the same effect on blood pressure. The iodine added to salt makes up less than 1% of the salt by weight. If you need to reduce sodium for blood pressure control, the type of salt does not matter — you need to reduce the total amount of salt you eat, regardless of whether it is iodized.

Can you get too much iodine from iodized salt?

Unlikely, unless you eat an unusually high amount of salt. The upper safe limit for iodine is 1,100 micrograms per day for adults. You would need to eat more than five teaspoons of iodized salt daily to reach that level, which is far more than most people consume. People with thyroid disease should discuss iodine intake with their doctor, but healthy people eating normal amounts of iodized salt do not risk iodine overload.

Is sea salt better than iodized salt?

Sea salt and iodized salt are nutritionally different. Sea salt contains trace minerals from seawater but is not iodized unless labeled as such. Iodized salt contains added iodine. Neither is objectively "better" — it depends on your iodine needs and overall diet. If you prefer sea salt and eat dairy, eggs, or fish regularly, you likely get enough iodine. If you eat mostly plants and use only non-iodized salt, you may need a supplement or another iodine source.

Does cooking with iodized salt destroy the iodine?

Heat does not destroy iodine in salt the way it destroys some vitamins. Iodine is stable at cooking temperatures. However, if you boil salt in water and discard the water, you lose some iodine. For maximum iodine retention, add iodized salt at the end of cooking or use it in dressings and sauces where the salt stays in the food.

What if I am pregnant and do not use iodized salt?

Talk to your doctor about iodine supplementation. Pregnancy increases iodine needs to 220 micrograms per day, and iodine deficiency during pregnancy raises the risk of miscarriage and developmental problems in the baby. Your doctor can recommend a prenatal vitamin with iodine or a separate iodine supplement. Do not wait until you are pregnant to address this — plan ahead if you are thinking about pregnancy.