Iodine: how much you need and where to get it

Why iodine matters

Iodine's main job is to help your body make thyroid hormones, which is why the authorised descriptions are that iodine contributes to normal thyroid function, to the normal production of thyroid hormones and to normal cognitive function. Most people give iodine no thought until their intake drops. Most people in the UK get enough without trying, because it comes through the diet in foods a lot of people eat every day.

How much do you need, and who falls short?

The UK reference intake is 140 micrograms a day for adults. Most people meet it from dairy and white fish. The group that most often falls short is anyone who has cut those out. A plant-based or strictly dairy-free diet is low in iodine unless it is planned, because plant foods and non-dairy milks are generally poor sources unless they are fortified. So most people get enough without a supplement, and only one specific group needs to pay attention.

Where iodine comes from

• Dairy, milk and yoghurt especially, is the main UK source.
• White fish and seafood are rich sources.
• Eggs add a modest amount.
• Most plant milks give little unless the label says they are fortified with iodine.

The kelp caution

Kelp needs a word of caution. Kelp and other seaweeds are naturally very high in iodine, which sounds ideal until you learn that the amount swings enormously from one batch to the next. That variability is why the British Dietetic Association advises caution with seaweed and kelp supplements: you cannot easily know how much iodine you are taking, and with iodine more is not better. The controlled alternative is a supplement with a measured, standardised amount declared on the label, so the dose is known.

A measured amount

Where iodine appears in our formulas, it is included as a measured, declared amount rather than a raw kelp dose you cannot quantify. Our prenatal, for example, provides a standardised 290 micrograms of iodine, so the amount you take is known and consistent. If you follow a plant-based diet, iodine is one of the nutrients the plant-based guide flags as worth planning for.