Mineral

Iodine

Iodine is needed to make thyroid hormones, which control metabolism and are vital for a baby’s brain development. It is found in dairy, fish and eggs.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review

What it is

Iodine is an essential trace mineral that the body needs to make thyroid hormones.

What it does

It is used by the thyroid gland to make hormones that control the body’s metabolism, and is especially important for brain development before birth and in early life.

Good sources

Dairy products such as milk and yoghurt, fish and shellfish, and eggs; seaweed is very rich but can provide too much.

Deficiency and who is at risk

Deficiency can cause an underactive thyroid and a swelling in the neck (goitre). It is a particular concern in pregnancy, as a lack can affect the baby’s brain development. People who avoid dairy and fish, including some vegans, may be at risk.

Balance

Can you have too much?

Too much iodine, for example from high-dose seaweed or kelp supplements, can also disturb thyroid function, so very high intakes should be avoided.

Education and reference only. This is general nutrition information, not personal advice, and does not give doses. Ask a pharmacist, GP or registered dietitian before starting supplements, especially with a health condition or in pregnancy.

Answers

Iodine: frequently asked questions

How do vegans get enough iodine?

Because dairy and fish are the main UK sources, vegans and people avoiding these foods may need a plant milk fortified with iodine or a suitable supplement. Seaweed is variable and can give too much, so it is not a reliable source.

Why does iodine matter in pregnancy?

Iodine is essential for making thyroid hormones that support the baby’s brain and nervous system development, so getting enough before and during pregnancy is particularly important.

Related

More on minerals and nutrition

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Sources

Where this is drawn from

  • NHS — Vitamins and minerals
  • British Dietetic Association (BDA)
  • UK Scientific Advisory Committee on Nutrition (SACN)

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