Iodine

Few plant foods contain much — so make sure you have a reliable source.

• Supplement: often needed
• Last checked: Oct 2026

Iodine is easy to overlook, because most people get it without thinking — from milk and fish. Vegans need to get it on purpose.

Why you need it

Your body uses iodine to make thyroid hormones, which run your metabolism and are essential for a baby’s brain development during pregnancy and childhood.

Why it matters for vegans

Milk, dairy and fish are where most people’s iodine comes from. Few plant foods contain much, and how much they have depends on the soil they grew in. So vegans are at higher risk of running low.

In Slovenia: iodised salt

In Slovenia, salt for eating and for making food must be iodised by law, and the National Institute of Public Health (NIJZ) names iodised salt as the country’s main source of iodine. Two catches:

• Not all salt counts. Unrefined sea salts that aren’t iodised contain too little iodine. Check the label.
• We are supposed to eat less salt, not more — high-salt diets are linked to high blood pressure, which is why The Vegan Society doesn’t recommend relying on salt for iodine.

If you do use iodised salt, add it at the end of cooking: boiling and steaming lose a good part of the iodine.

Where to get it reliably

• A supplement with potassium iodide or potassium iodate, of no more than 150 µg a day, or
• Iodine-fortified plant milk — The Vegan Society suggests at least 500 ml a day of a product with around 25 µg per 100 ml. Not all plant milks are fortified; check the label.

Not seaweed. Its iodine content is unpredictable and can be far too high. Don’t eat brown seaweed or kelp more than once a week — especially in pregnancy — and don’t use kelp supplements.

How much?

The European Food Safety Authority (EFSA) sets an adequate intake of 150 µg a day for adults and 200 µg in pregnancy and breastfeeding. The upper limit is 600 µg a day.

If you could become pregnant, make sure you get enough before pregnancy, not only once you are pregnant.

Should you supplement?

Many vegans should: a daily supplement or fortified plant milk is the simplest reliable source. Too little and too much iodine can both upset your thyroid, so stay near the recommended amount.

If you have a thyroid condition — especially an overactive thyroid — talk to your doctor before taking iodine.

How to check

There’s no good everyday test: urine iodine shows how a whole population is doing, not how one person is. The best check is your routine — do you have a reliable source every day?

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