Nutrient glossary
What is iodine?
Iodine is the raw material of thyroid hormone, which sets your metabolic rate; milk and white fish are the UK staples for it.
Reviewed 20 July 2026. General information, not medical advice.
The short version
Your thyroid cannot make its hormones without iodine, and those hormones set the pace of metabolism, growth and brain development. It matters most in pregnancy, when requirements rise and low intake affects the baby’s development.
The UK gets most of its iodine from dairy and white fish rather than iodised salt. Plant milks vary: some are fortified, many are not, so label-checking matters for anyone fully plant-based. Seaweed swings from useful to excessive: kelp can overshoot safe intakes badly, which is why kelp supplements carry warnings.
Daily reference
140 µg a day
The adult reference is 140 µg a day. Generic food databases measure iodine patchily, so Nutrigate shows it without ranking foods by it.
This is the fixed adult reference used across these pages. In the app, your amount adjusts to your body and way of eating.
Best food sources of iodine
| Food | Per serving | Per 100g |
|---|---|---|
| Milk (semi-skimmed) | 75 µg | 30 µg |
| Eggs | 49 µg | 49 µg |
| Shrimp / Prawns | 41 µg | 41 µg |
| Greek Yogurt | 41 µg | 24 µg |
| Sardines (canned) | 32 µg | 35 µg |
| Cottage Cheese | 29 µg | 26 µg |
| Pizza (cheese) | 21 µg | 10 µg |
| Salmon Fillet | 21 µg | 14 µg |
Common questions
- How do vegans get iodine?
- A fortified plant milk or a measured iodine supplement is the reliable route. Kelp is unreliable: its iodine content varies enormously and can be excessive.
- Is sea salt a good iodine source?
- No, sea salt contains very little iodine unless it is specifically iodised, which most UK salt is not.