Iodine | Health Navigator NZ

Iodine helps make thyroid hormone which is vital to maintain the body’s metabolic rate, as well as for normal growth and development. Iodine deficiency can lead to thyroid disease such as goitre or hypothyroidism and impair brain development.

On this page, you can find the following information:

Why is iodine important?
Why is iodine in pregnancy and breastfeeding important?
Which foods contain iodine?
Who is at risk of iodine deficiency?
What about iodine supplements?

Why is iodine important?

Although only required in very small amounts, iodine is an essential nutrient for everyone. Iodine helps make thyroid hormone which is vital to maintain your body’s metabolic rate, as well as for normal growth and development. Iodine deficiency can lead to thyroid disease such as goitre or hypothyroidism and impair brain development.

Why is iodine in pregnancy and breastfeeding important?

It is particularly important that unborn babies and young children have adequate intakes of iodine. Severe iodine deficiency in pregnancy has been associated with miscarriages, stillbirth, preterm delivery, and congenital abnormalities in babies. Children of mothers with severe iodine deficiency during pregnancy can have intellectual disabilities and problems with growth, hearing, and speech. In the most severe form, an underactive thyroid can result in cretinism (a syndrome characterized by permanent brain damage, deaf mutism, spasticity, and short stature), although this has become rare worldwide.

It is recommended that pregnant and breastfeeding women take a 150 micrograms (mcg) iodine only tablet daily, as well as eating foods which are important sources of iodine.
The recommended registered tablet can be purchased at pharmacies (or at a lower cost, when prescribed by your doctor or midwife).
Talk to your doctor, midwife, dietitian, nurse or pharmacist to find out more.

Which foods contain iodine?

Seaweed (such as kelp, nori, kombu, and wakame) is one of the best food sources of iodine.
Other good sources include fish and other seafood, eggs, milk, milk products, soy milk, soy sauce.
Commercially prepared bread – iodised salt is added to commercially prepared bread in New Zealand (except organic or unleavened varieties).

If using salt, always choose iodised salt. Fancy, and often expensive, sea salt and rock salts don't contain iodine.
Note: some of these foods may not be suitable for pregnant people because of the risk of listeria. Read more about listeria and pregnancy.

Who is at risk of iodine deficiency?

Diets that exclude foods that are good sources of iodine in the diet can have a negative impact on your iodine status. For example, vegan diets and vegetarian diets with no fish or seafood products and little dairy products. Also, people who consume very little bread may be at risk of iodine deficiency given that bread is a major source of iodine in New Zealand.

What about iodine supplements?

While consumption of iodine containing supplements and kelp tablets will increase your iodine intake, care needs to be taken when considering this type of supplementation as this may lead to an intake of iodine beyond the safe upper level of intake.

Kelp tablets and other iodine supplements should only be taken under supervision of a doctor or dietician, because the iodine content of these supplements is extremely variable. Taking high doses of iodine for a long period of time could affect your thyroid gland.

Limiting salt intake is an important factor to help manage high blood pressure and other health conditions. However, when using salt, opt for iodised salt.