What is iodine?
Iodine is a nutrient found in most foods, but usually in small amounts. Unfortunately, it's hard for New Zealanders to get enough iodine, even with a balanced diet, because the soil contains little iodine. This means vegetables, fruits and grains grown in New Zealand have very low levels of iodine compared with food grown in other parts of the world.
Why do you need iodine?
Iodine is important for thyroid hormones, which help maintain the body's metabolic rate and support children's growth and development. It is particularly important for toddlers, infants and unborn babies, as it's essential for brain development.
Low iodine levels in our diet can cause:
- poor growth and development in infants and children
- thyroid diseases
- goitre (swelling of the thyroid gland in the neck).
How much iodine do you need?
The New Zealand Ministry of Health says adults need about 150 micrograms of iodine a day. Pregnant and breastfeeding women need more, children and infants need less.
Iodine when pregnant and breastfeeding
When you're pregnant or breastfeeding, you need more iodine to support your baby's brain development. Even with a balanced diet that includes iodine-fortified foods, you will probably not get enough iodine. The Ministry of Health advises women to take an iodine supplement, and to eat more iodine-rich foods.
For more information on iodine and having a healthy diet during pregnancy refer to:
Iodine fortification of foods
Fortification is when extra nutrients are added to food and drinks during manufacturing. In some cases, manufacturers are required by law to add nutrients to a particular food to meet a significant health need.
Iodised salt in bread
Iodine has been added to salt since 1924 to prevent iodine deficiencies. In 2009, food regulations made it mandatory for bread manufacturers to use iodised salt in most breads, after studies found mild to moderate iodine deficiencies in some groups, including children.
Some breads and bread products don't have to be fortified with iodine, including:
- organic and unleavened breads, pizza bases
- pastries and cakes
- biscuits and crackers.
Are iodine-fortified foods labelled?
Yes. Foods that contain iodised salt, like breads, will list this in the ingredients.
Iodine in other foods
Other good food sources of iodine include:
- low-fat milk and milk products
- foods that contain seaweed, such as sushi.
While you should limit how much salt (sodium chloride) you eat, using iodised salt in cooking or at the table will help provide you the iodine you need. Note, most rock or sea salts sold in New Zealand do not contain much iodine.
While some people have an adverse reaction to large amounts of iodine, it’s unlikely that the amount they would get from a typical diet – including from iodine-fortified bread – is enough to affect their health.
Monitoring iodine levels in New Zealand
MPI and the Ministry of Health together monitor the effectiveness of mandatory bread fortification by:
- regularly checking the iodine content of foods, and using this to estimate New Zealanders’ dietary intake of iodine
- measuring the iodine status of the population as part of the Ministry of Health New Zealand Health Survey.
The most recent surveys show New Zealanders' iodine intake has increased significantly since fortification and suggest most adults and children now have adequate iodine intakes.
- Download the June 2016 report on mandatory iodine fortification and iodine status [PDF, 497 KB]
- Download the July 2014 report on children’s iodine intake since bread fortification [PDF, 490 KB]
- Monitoring the health impacts of mandatory folic acid and iodine fortification – Australian Institute of Health and Welfare website
Find out more
Who to contact
If you have questions about iodine in food, email firstname.lastname@example.org.