Iodine is a trace element your thyroid needs to make its hormones, thyroxine (T4) and triiodothyronine (T3), which regulate metabolism in almost every cell. Its authorised benefits are that iodine contributes to the normal production of thyroid hormones and normal thyroid function, normal energy-yielding metabolism, normal cognitive function, normal functioning of the nervous system and the maintenance of normal skin. Adults need about 150 µg a day, more in pregnancy and while breastfeeding. Iodised salt, sea fish and dairy are the main sources, so people who eat a vegan diet or little salt are more likely to fall short.
Key facts about iodine
- Daily need (D-A-CH reference values, revised 2025): 150 µg for adults, 220 µg in pregnancy and 230 µg while breastfeeding.
- The nutrient reference value (NRV) used on EU and Swiss labels is 150 µg.
- Safe upper level (EFSA): 600 µg a day from all sources for adults, including during pregnancy.
- Swiss table salt has been iodised since 1922; iodised salt now contains 25 mg of iodine per kilogram, or 25 µg per gram.
- Sea fish such as pollock, haddock and cod provide roughly 100 to 250 µg per 100 g; plant foods usually contain very little.
- Dried seaweed varies enormously: kombu (kelp) can contain more than 1,000 µg in a single gram.
What does iodine do for the body?
The body cannot make iodine and stores only a small amount, mostly in the thyroid gland. The thyroid traps iodine from the blood and builds it into T4 and T3. These hormones set the pace of energy use, body temperature, heart rate and digestion, and they are essential for growth and brain development in children. Without enough iodine, the thyroid cannot produce enough hormone and may enlarge (goitre) as it tries to capture more.
The authorised benefits of iodine
In the EU and Switzerland, only health claims listed in the official register may be made for nutrients. For iodine, the authorised wording is that iodine contributes to:
- the normal production of thyroid hormones and normal thyroid function;
- normal energy-yielding metabolism;
- normal cognitive function;
- normal functioning of the nervous system;
- the maintenance of normal skin.
Many online lists promise far more, from "detox" to weight loss. Those effects are not authorised and not supported by good evidence. What iodine really does is simpler and more important: it keeps the thyroid supplied so that the rest of the body can run normally.
Iodine benefits for women and men
Women and men need the same 150 µg a day, and iodine does the same work in both. The differences lie in life stage and risk.
Women
During pregnancy the mother's thyroid makes more hormone, and the baby depends on her iodine for its own thyroid and brain development, especially in the first months. That is why the reference value rises to 220 µg in pregnancy and 230 µg while breastfeeding. The German Nutrition Society advises pregnant and breastfeeding women to take an iodine supplement of 100 to 150 µg a day, in addition to iodised salt, after talking to their doctor. Thyroid conditions are also more common in women, which is one more reason to discuss any supplement first.
Men
For men, adequate iodine supports the same normal thyroid function, energy-yielding metabolism and cognitive function. There is no good evidence that extra iodine above the daily need gives men additional benefits, for example for testosterone or muscle. Men who eat little fish or dairy, cook without iodised salt or follow a vegan diet are the ones who should check their intake.
Is iodine good for your skin and hair?
Iodine contributes to the maintenance of normal skin, which is an authorised claim. People with an underactive thyroid often have dry, rough skin and dull hair, so a lack of iodine can show on the outside. That does not mean more iodine gives better skin or faster hair growth: once your needs are met, extra iodine adds nothing, and too much can upset the thyroid. Iodine solutions applied to the skin are antiseptics for small wounds, not a cosmetic or a nutrient. For the vitamins and minerals that matter most for skin, read our guide to the best vitamins for your skin.
What is iodine used for?
When people search for "iodine uses", they meet several very different products:
- Nutrition: iodide in iodised salt, foods and multivitamins covers the daily need of a few hundred micrograms at most.
- Disinfection: povidone-iodine solutions disinfect skin before operations and small wounds. They are for external use and must not be swallowed.
- Medical imaging: iodine-based contrast agents make blood vessels and organs visible on X-ray and CT scans.
- Radiation emergencies: high-dose potassium iodide tablets block the uptake of radioactive iodine by the thyroid. In Switzerland they are distributed to households near nuclear power plants and should be taken only when the authorities say so.
Which foods contain iodine?
Iodine content depends on the soil, animal feed and salt used in processing, so figures vary. Swiss and Central European soils are naturally low in iodine, which is why fruit, vegetables and grains grown here provide very little.
| Food | Iodine (approx.) |
|---|---|
| Iodised salt (Switzerland) | 25 µg per gram |
| Pollock, haddock, cod | 100 to 250 µg per 100 g |
| Prawns | about 130 µg per 100 g |
| Hard cheese | about 20 to 40 µg per 100 g |
| Milk and yoghurt | about 10 to 15 µg per 100 g |
| Egg (one) | about 5 to 10 µg |
| Nori (dried) | about 15 to 40 µg per gram |
| Kombu / kelp (dried) | often over 1,000 µg per gram |
About 4 g of iodised salt a day supplies 100 µg, two thirds of an adult's need. If you use salt, choose the iodised version for cooking and baking, but do not eat more salt for the sake of iodine. Processed foods and restaurant meals in Switzerland are often made with non-iodised salt.
Do vegans get enough iodine?
Often not. The richest natural sources are fish and dairy, and studies in Europe have repeatedly found lower iodine status in vegans than in people with a mixed diet. Seaweed is not a reliable solution, because its iodine content is unpredictable and can be far too high. A plan for vegans is iodised salt in home cooking plus a supplement with a moderate, known amount of iodine. Iodine sits on the same list of critical vegan nutrients as vitamin B12 and iron, whose needs differ between women and men.
Signs of iodine deficiency
Mild iodine deficiency usually causes no clear symptoms. When intake stays too low for a long time, thyroid hormone levels can fall, and signs may include:
- a swelling at the front of the neck (goitre);
- tiredness, feeling cold and slower thinking;
- weight gain, constipation, dry skin;
- in pregnancy, a risk to the baby's growth and brain development.
The same signs have many other causes. Iodine status in a population is measured in urine, but for an individual a doctor will usually check thyroid hormones (TSH, fT4) and examine the thyroid.
Can you take too much iodine?
Yes. The European Food Safety Authority set the tolerable upper intake level for adults at 600 µg a day from all sources. Regularly taking more can disturb thyroid function and may trigger an over- or underactive thyroid, especially in people with existing thyroid disease, such as Hashimoto's thyroiditis or nodules. The biggest risks are seaweed products and high-dose iodine supplements.
Iodine drops, liquid and "nascent" iodine
Iodine drops and liquid iodine are often sold with promises of "more energy", "detox" or "hormone balance". None of these claims is authorised. Many products supply several hundred or even thousands of micrograms per dose, well above both the daily need and the upper level. If you use one, check the amount per drop, add it to your other sources and stay below 600 µg in total. Never swallow antiseptic iodine solutions. If you have a thyroid condition or take thyroid medication, ask your doctor before taking any iodine supplement.
Iodine in Sanbera formulas
Daily Essential Women and Daily Essential Men each provide 37.5 µg of iodine per daily serving of three tablets, 25 % of the NRV. That is a moderate amount meant to complement iodised salt and a varied diet, not to replace them; together with normal food it stays well below the 600 µg upper level. Iodine contributes to the normal production of thyroid hormones and normal thyroid function and to normal cognitive function. Both formulas also contain 12.5 µg of selenium (23 % NRV), which contributes to normal thyroid function; our article on selenium benefits explains this partner nutrient. The Nightly Reload formulas contain no iodine. Not sure which supplements are worth taking at all? See which dietary supplements are most useful.
Frequently asked questions
What is iodine good for?
Iodine is needed to make thyroid hormones. It contributes to the normal production of thyroid hormones and normal thyroid function, normal energy-yielding metabolism, normal cognitive function, normal functioning of the nervous system and the maintenance of normal skin. In pregnancy and childhood it is essential for normal growth and brain development. Adults need about 150 µg a day.
Is iodine good for you every day?
Yes, your body needs iodine every day because it stores only a little. About 150 µg a day is enough for adults, and the safe upper level is 600 µg from all sources. Iodised salt, sea fish, dairy and a multivitamin with a moderate dose cover the need. Daily high-dose iodine, for example from kelp tablets, is not recommended without medical advice.
Does iodine detox the body?
No. There is no scientific evidence that iodine removes toxins, heavy metals or other substances from the body, and "iodine detox" is not an authorised health claim. Your liver and kidneys do that work. Protocols that use very high iodine doses can exceed the safe upper level of 600 µg a day many times over and may disturb thyroid function.
Why is iodine added to salt?
Salt is iodised because soils in Switzerland and much of Europe contain little iodine, so local food alone did not provide enough. Before Switzerland introduced iodised salt in 1922, goitre was widespread in Alpine regions. Iodised salt is a cheap, reliable way to reach the whole population; Swiss iodised salt today contains 25 µg of iodine per gram.
Should pregnant women take iodine?
Pregnant women need more iodine, 220 µg a day, because the baby's thyroid and brain depend on it. The German Nutrition Society recommends a supplement of 100 to 150 µg a day in addition to iodised salt during pregnancy and breastfeeding. Women with a thyroid condition should first speak to their doctor, who will choose the right dose.
Sources
- German Nutrition Society (DGE): Reference values for iodine (2025)
- EFSA Panel on Dietetic Products, Nutrition and Allergies (2014): Scientific opinion on Dietary Reference Values for iodine
- National Institutes of Health, Office of Dietary Supplements: Iodine, Health Professional Fact Sheet
- World Health Organization: Iodine deficiency
- European Commission: EU Register of nutrition and health claims
This article is for general information and does not replace advice from a doctor or pharmacist. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle.