NZ bread now fortified with iodine

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. 

 

In the 1920s, iodine was added to table salt in an effort to increase the amount of iodine consumed by the population. In those days salt was used freely both at the table and in cooking. The major source of iodine in the New Zealand diet for many years, though, was milk due to the cleaning products used in the dairy industry which contained iodophores. However, this is no longer the case as changes in cleaning regimes and products since the 1970s have reduced the amount of iodine in milk.

 

As a high salt intake has been linked with increased blood pressure, strokes and heart disease over the past few decades, New Zealanders have been encouraged to limit or eliminate the use of salt in cooking and at the table in an attempt to reduce this risk. There has also been an increase in the amount of processed foods eaten, which relates to the reduced amount of iodine being eaten as the salt used in manufactured foods tends not to be iodised. This has been compounded by the recent popularity of ‘natural’ rock and sea salts as they are not iodised either.

 

All of these factors have resulted in less iodised salt being eaten. Possibly as a consequence, recent 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).Those most at risk are pregnant and breastfeeding women, as they need sufficient iodine for the mental and physical development of their babies.

 

In an attempt to reverse this trend, bread in New Zealand will be fortified with iodine from October 9 this year. Bread was chosen as a suitable food for fortification as it is a commonly-eaten food and relatively simple and cheap to substitute iodised salt without affecting taste or other properties. Manufacturers must list ‘iodised salt’ in their ingredients list.

 

Even though we will be eating more iodine through our daily bread, it is still important to enjoy other iodine-rich foods such as fish, eggs, dairy products and seafood.

 

 

Media comment from the Science Media Centre:

 

Media report on latest Otago University findings:

 

FSANZ fact sheet: