Iodine

Iodine is essential in our diet to ensure the thyroid gland in our neck functions normally. The thyroid is responsible for growth, brain development and the rate at which we burn energy.

How much iodine do we need?

 

 

Age (years)

RDI*
Iodine (µg/day)

Infants

7-12 months

110

Children

1-3

90

 

4-8

90

Boys

9-13

120

 

14-18

150

Girls

9-13

120

 

14-18

150

Men

19-70+

150

Women

19-70+

150

Pregnant women

14-50

220

Breastfeeding women

14-50

270

*Recommended Daily Intake
 

Who needs more and why?

Many New Zealanders currently have low levels of iodine.

Pregnant women need iodine for their developing baby - see our Pregnancy & Breastfeeding page for more details

Which foods contain iodine?

The main sources of iodine for New Zealanders are now of marine origin - including seaweed, seafood and fish - along with dairy products and eggs. Bread in New Zealand is now fortified with iodine (except for organic and salt-free bread, and some home-bake bread mixes).

How can I get enough?

Limiting salt intake continues to be an important factor in reducing blood pressure, so if you choose to use salt for cooking and at the table, iodised salt is the way to go. Sushi is also a great source of iodine. Eating bread that is made with iodised salt will increase your iodine level without increasing your salt intake.
Iodine or kelp supplements should only be taken on the advice of your doctor.

Iodine deficiency

The iodine content of food is affected by soil, irrigation, fertilisers and cooking.  Unfortunately, New Zealand soils are low in iodine, resulting in low iodine levels in locally grown foods.  Iodophores (cleaning products used by the dairy industry) were once the main source of iodine for New Zealanders, but since the 1970s changes in industry practices have reduced the amount of iodine in milk. There has also been a decline in the use of iodised salt.  As a result, studies have shown the re-emergence of mild to moderate iodine deficiency across most age groups in New Zealand. Even at a mild level, iodine deficiency can affect hearing, intelligence and mental capability. Cases of severe iodine deficiency can result in goitre (swelling of the thyroid gland in the neck with associated lethargy) and hypothyroidism (caused by insufficient production of the thyroid hormone by the thyroid gland).