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Iodine: the daily reference intake

Iodine has one job — it is the atom in thyroid hormone — and one of the largest pregnancy increases in the table, from 150 to 200 micrograms a day. It is also the nutrient this site cannot compute food figures for, because the food composition data behind the rest of the site does not carry iodine.

These are published population reference values, not a diagnosis and not a prescription. A reference intake describes what covers a healthy group; it cannot tell you your own status, and no page can. Pregnancy, chronic illness, medicines and malabsorption all change the picture — take those questions to a doctor, midwife, pharmacist or dietitian.

Iodine by age, sex and life stage

This page carries the adult values. EFSA also publishes lower adequate intakes for children; they are not reproduced here.

Why this page has no food table

Every other nutrient page here ranks ordinary foods using the USDA FoodData Central composition snapshot. That snapshot does not include iodine, and inventing values would be worse than leaving the section out. So this page describes sources instead of ranking them.

The practical carriers in a Nordic or Baltic diet are iodised salt, milk and dairy, sea fish, and eggs. Bread made with iodised salt contributes wherever bakeries use it. Seaweed contains far more than anything else and is the one source where more is not better.

Iodised salt is a public-health measure, not a seasoning choice

Iodine deficiency is the commonest preventable cause of impaired brain development worldwide, and the standard control measure everywhere is salt iodisation. Iodine intake in the Nordic and Baltic region has been a recurring public-health concern, particularly among women of childbearing age, and iodised salt is the standard national response.

Two modern habits work against it. Sea salt, rock salt and fleur de sel are usually not iodised, so replacing table salt with them removes iodine without replacing it. And salt-reduction advice, which is correct on its own terms, reduces the vehicle at the same time. Buying iodised salt and using less of it is the way both messages hold.

Pregnancy is the sharp end

The fetal thyroid does not function for the first months of pregnancy, so early fetal brain development runs entirely on maternal thyroid hormone, and maternal iodine requirement rises before most women know they are pregnant. EFSA raises the adequate intake from 150 to 200 micrograms a day for pregnancy and breastfeeding.

Iodine deficiency in pregnancy is one of the few nutrition topics where the evidence for harm at population level is strong and long-established. It is also one where self-medication is a bad idea, because high-dose iodine can itself disturb the thyroid. Antenatal care is the right place for this question.

Both ends of the range cause trouble

Too little iodine causes goitre and hypothyroidism; too much can cause hyperthyroidism in some people and hypothyroidism in others, particularly where there is underlying thyroid autoimmunity. This U-shaped risk is why the gap between the 150 microgram reference intake and the 600 microgram upper level matters, and why kelp supplements are the one product category worth being actively suspicious of.

The upper level

The tolerable upper intake level for adults is 600 micrograms a day. Both too little and too much iodine disturb the thyroid, which is unusual — for most nutrients only the deficient end causes trouble. Seaweed is the practical hazard: some kelp products carry thousands of micrograms per gram and can push intake far past the ceiling in a single serving.

Ordinary food against the 150 microgram adult adequate intake

The food composition snapshot behind this site does not carry iodine values, so there is no computed table on this page. Inventing numbers would be worse than leaving it out; the sections above describe where it comes from instead.

Iodine for one group at a time

Sources: EFSA Dietary Reference Values · Regulation (EU) No 1169/2011, Annex XIII · USDA FoodData Central SR Legacy (food composition) · EFSA scientific opinion on dietary reference values for iodine (2014) · World Health Organization guidance on iodine deficiency and salt iodisation · checked 2026-09-06

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