A short list, because there are not many good sources, and it is one of the few nutrients a broad, healthy diet does not automatically cover.
Seafood
The best source by some distance. White fish especially, and oysters and mussels if they are your thing. Tinned fish counts.
Dairy
Milk, yoghurt and cheese all contribute, and for a lot of Australians dairy is the second biggest source after bread.
Eggs
A modest contribution, mostly from the yolk.
Seaweed
The richest source of iodine there is, and the most variable. How much it carries depends on the species, where it was grown and how it was processed.
Nori, the sheets used for sushi, carries a useful amount and is fine to eat regularly.
Brown seaweeds are a different matter. Kombu, kelp and similar varieties can carry several times the daily upper level in a single serve. Australia has seen this go wrong before, when a soy milk made with kombu was recalled in 2009 after people who drank it developed thyroid problems.
So seaweed is a real source, and a good one in the right form. Keep the brown varieties occasional, and treat raw seaweed and kelp supplements with caution for the same reason.
Iodised salt
If you use salt at home, check the packet. Plenty of salt is not iodised, including most of the fancier ones. Sea salt and pink salt are poor sources of iodine.
Bread
Commercial bread made with iodised salt, which is most of it. Organic loaves and home bread mixes are the exceptions, so check your loaf if bread is carrying the load for you.
The takeaway: Seafood, dairy, eggs, iodised salt and most commercial bread. If you eat little of the first two and your bread is organic or home baked, you may be short, and iodised salt at home is the simplest fix.
The science behind this post:
- Food Standards Australia New Zealand. Australian Food Composition Database. Iodine content of seafood, dairy, eggs, seaweed and salt. foodstandards.gov.au
- Food Standards Australia New Zealand. Iodine in seaweed. Brown seaweeds such as kombu can contain very high levels of iodine; consumers are advised to limit consumption. foodstandards.gov.au
- National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand: Iodine. nrv.gov.au