Iodine in Tasmania

Iodine in Tasmania

Tasmanians are now getting the ideal amount of iodine in their diets, thanks to an Australian first initiative.

Although iodine only makes up a tiny fraction of our diet, in the late 1990s Tasmanians and many other Australians simply weren't getting enough from the food they ate.

Even mild iodine deficiency is well recognised as having negative effects on growth and intellectual development in babies and children.

Tasmania became the first state in Australia to work towards improving iodine levels in recent times. In 2001 the baking industry was asked to voluntarily replace the salt used in bread making with iodised salt, as a preliminary step towards improving iodine nutrition. This action in Tasmania influenced action at a national level and in 2009 it became law in Australia and New Zealand for iodised salt to replace regular salt in bread, albeit with some minor exceptions.

In 2011, a total of 320 children from 35 primary schools in Tasmania gave us a small urine sample.  These urine samples were tested for iodine and the combined results suggest the Tasmanian population is now getting enough iodine from food.

DePaoli KM, Seal JA, Burgess JR, Taylor R. Improved iodine status in Tasmanian school children after fortification of bread: a recipe for national success. Medical Journal of Australia, 189: 492-494

The Department of Health and Human Services has tracked improvement in iodine nutrition through urinary iodine surveys of school children since 1998. These surveys are an important component of an ongoing program to ensure Tasmanians get the optimal level of iodine from food.

Why is iodine important?

Iodine is an essential nutrient we need in very small amounts for a healthy thyroid and for normal growth and development.  Iodine is very important during pregnancy and breastfeeding for the normal development of a baby's brain and nervous system. Even mild to moderate iodine deficiency can affect growth and development in unborn babies, infants and young children.  Cretinism, which is a severe intellectual disability combined with stunted growth, occurs in areas of the world where iodine deficiency is severe.  In such areas it is common to see people, particularly women, with an enlarge thyroid gland in the neck, known as goitre.

Do you get enough iodine?

In Tasmania, sources of iodine include dairy milk, bread baked with iodised salt and seafood. The amount in other foods like cereals and vegetables varies depending on where they are grown. Most people will now get enough iodine in their diet if they eat bread and have dairy foods (eg cow's milk or yoghurt) on most days of the week as part of a healthy diet.

Foods that are a good source of iodine include:

  • dairy milk
  • bread
  • seafood such as flathead, tuna and salmon (including tinned varieties), oysters, mussels, prawns and crayfish.

Pregnant and breastfeeding women need more iodine than they will get from food alone.  The National Health and Medical Research Council now advises pregnant and breastfeeding women to take a supplement with 150 micrograms of iodine a day. If you are pregnant, breastfeeding or considering becoming pregnant, talk to your doctor or pharmacist about a suitable supplement.

Iodine levels in Tasmania

Tasmania has had a long history of iodine deficiency because of the nature of the state's soil.

Prior to the 1950s iodine deficiency was widespread. In the 1950s and 1960s iodine tablets were provided for school children and women who were pregnant and breastfeeding. Later in the 1970s iodine was added to bread.  The addition of iodine to bread in the 1970s was ceased a short time after it commenced as it appeared people were getting too much iodine.  Iodine-based cleaning agents had become popular in the dairy industry leading to an over supply of iodine in the Tasmanian diet.  Iodine-based cleaning agents used in the dairy industry are thought to have provided protection against iodine deficiency through the 1970s and 1980s as small quantities of iodine remained present in the milk supply.  The dairy industry no longer uses iodine-based cleaning agents but still uses iodine-based solutions on cows' teats after milking to prevent mastitis. Some of this iodine remains in the milk so cow's milk remains a useful source of iodine.

In the late 1990s some research by the Menzies Research Institute found iodine deficiency was again a problem in Tasmania.  Similar reports of iodine deficiency were emerging in other parts of Australia and New Zealand.  The Department of Health and Human Services raised this concern with national authorities and investigated a number of interim strategies to increase iodine in Tasmania while a more permanent solution could be investigated nationally. After consideration of a range of options, it was decided that switching to iodised salt in place of regular salt in bread was the most practical solution.

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