Iodine is needed to make thyroid hormone, and needs rise in pregnancy. Iodised salt is the main source in many countries.
Calculator Official intake Study doses Best form Safety Sources
AI (adequate intake)
| Men | 150 µg |
|---|---|
| Women | 150 µg |
| Pregnancy | 200 µg |
| Breastfeeding | 200 µg |
Safe upper limit: 600 µg a day
RDA (recommended dietary allowance)
| Men | 150 µg |
|---|---|
| Women | 150 µg |
| Pregnancy | 220 µg |
| Breastfeeding | 290 µg |
Safe upper limit: 1,100 µg a day
Source: National Academies (NASEM) 2019
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
150 µg a day
Several major medical societies (including the American Thyroid Association) advise a prenatal supplement with 150 µg iodine a day before and during pregnancy and while breastfeeding.
Practical pick
Potassium iodide, salt weight (~76% I)
Why: Potassium iodide gives a precise amount and is absorbed almost completely (about 96%). It is the form in most prenatal vitamins that contain iodine.
Alternatives: Avoid kelp and seaweed pills: seaweeds range from 16 to almost 3,000 µg iodine per gram.
Iodised salt, fish, seaweed, dairy, eggs.
People with thyroid disease should ask their doctor before taking iodine.
Kelp and seaweed supplements can contain very high and uneven amounts of iodine.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.
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