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Summary
- Iodine helps the thyroid gland work well and is needed for normal growth and development. It is very important for babies’ brain and nerve development during pregnancy and breastfeeding.
- Not getting enough iodine can cause problems with growth and learning in children.
- Pregnant and breastfeeding women need more iodine. They should take a supplement with 150 micrograms of iodine every day and eat foods that are good sources of iodine. Women with pre-existing thyroid conditions, coeliac disease or lactose intolerance should talk to their doctor before taking a supplement.
- Tasmanians have had low iodine levels in the past, but this has improved over the last 20 years by adding iodised salt to bread.
- Good sources of iodine are cow’s milk, bread made with iodised salt and seafood. Eating these foods regularly helps most people get enough iodine.
- A Tasmanian government program checks iodine levels in school children every five years and looks at changes in diet and cow’s milk iodine levels to track iodine intake.
Why we need iodine
Iodine is a nutrient we need regularly in small amounts for a healthy thyroid and for normal growth and development.
Extra iodine is needed during pregnancy and breastfeeding to meet the baby’s needs.
Even a mild lack of iodine can affect the growth and development of unborn babies, infants and young children.
Iodine in food
Our bodies cannot store iodine, so we need to eat foods high in iodine often. Good sources of iodine are:
- Cow’s milk and yoghurt.
- Bread – most store-bought bread in Australia now contains iodised salt. Organic bread and bread mixes for making bread at home may not contain iodised salt.
- Fish and seafood - fish such as flathead, tuna and salmon (including tinned varieties) and seafood such as oysters, mussels, prawns and crayfish. For information about choosing seafood during pregnancy see eating for pregnancy and breastfeeding.
Iodine during pregnancy and breastfeeding
During pregnancy and breastfeeding more iodine is needed for the baby’s brain and nervous system development. Pregnant and breastfeeding women need more iodine than they can get from food alone because their needs almost double during this time.
Not enough iodine can lead to learning problems and affect physical development in babies and children.
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists and the National Health and Medical Research Council recommend that all women who are pregnant, breastfeeding or considering pregnancy take a supplement containing 150 micrograms of iodine each day.
If you have coeliac disease, are lactose intolerant or have a pre-existing thyroid condition, talk to your doctor or pharmacist before taking an iodine supplement. You may need to take a different amount of iodine.
If you are pregnant, breastfeeding or planning to become pregnant, talk to your doctor or pharmacist about a suitable supplement.
For more information about eating well during pregnancy, see eating for pregnancy and breastfeeding.
The history of iodine levels in Tasmania
Iodine deficiency in Tasmania was first reported in the 1830’s and was widespread until the 1950’s due to the naturally low iodine in Tasmanian soil. Before this, Tasmanian Aboriginal people got iodine from seaweed baskets used to carry water and a diet high in seafood.
A number of public health measures have been put in place to correct iodine levels in Tasmania over the last 70 years.
- 1950s and 60s - Iodine tablets provided for school children and pregnant and breastfeeding women.
- 1970s - Iodine added to bread (fortification), and iodine based cleaning agents became popular in the dairy industry. Then Tasmanians appeared to be getting too much iodine and iodine stopped being added to bread.
- 1970s and 80s - Iodine based cleaning agents continued to be used in dairy industry. This was thought to have protected against iodine deficiency over this time as small quantities of iodine were present in the milk supply.
- 1990s - Use of Iodine based cleaning agents declined in the dairy industry. Iodine deficiency again became a problem in Tasmania.
- 2001 - Baking industry in Tasmania asked to voluntarily replace salt used in making bread with iodised salt.
- 2009 - It became law in Australia and New Zealand for iodised salt to replace regular salt in bread.
It is important that we continue to monitor iodine in the Tasmanian population to make sure everyone gets the right amount of iodine from food.
Action on iodine
Thyroid Advisory Committee
In response to changes in iodine levels in the Tasmanian population, the Thyroid Advisory Committee was established in 1968. The Committee’s role is to coordinate thyroid disease research in Tasmania and advise the Minister for Mental Health and Wellbeing on thyroid disease and iodine nutrition policy.
Key priorities for iodine action in Tasmania include:
- Overseeing the monitoring of iodine nutrition in the population through five-yearly urinary iodine surveys of Tasmanian school children.
- Increasing awareness among health professionals and pregnant and breastfeeding women about the importance of taking an iodine supplement.
- Regularly checking the iodine content of cows’ milk (a major source of dietary iodine).
- Working with the Tasmanian Dairy Industry Authority to understand factors affecting iodine levels in milk.
Tasmanian school student urinary iodine surveys
Since 1998 the urinary iodine levels of school children have been monitored to track improvements in iodine nutrition. These surveys are important to ensure Tasmanians get an optimal level of iodine from food. The Tasmanian Government undertakes these surveys every five years. The next school children urinary iodine survey will occur in 2026.
A sample of Tasmanian primary schools is selected to participate. Students from some classes are asked to complete a consent form and provide a single urine sample. Participation is voluntary. The urine samples are then tested for iodine.
Because individual urinary iodine levels change from day to day and even within a day, a single urine sample is not useful for testing individual students. It is only helpful when testing is done on a large number of people and the results are looked at all together. When this is done, it helps us to know whether Tasmanian children are getting enough iodine in their diet.
The graph below shows that since the addition of iodised salt to bread, the iodine intake of school children in Tasmania has remained adequate, indicating that levels among the general population are also acceptable.
For more information
Information for Health Professionals
Iodine supplementation for Pregnant and Breastfeeding Women (NHMRC)
Vitamin and Mineral Supplementation and Pregnancy (RANZCOG)
Consumer information
Iodine and your health (Healthdirect)
Iodine deficiency (Healthdirect)
Eating well during pregnancy (Healthy Tasmania)
Reports
Barriers and enablers to maternal iodine supplement use in Tasmania Report May 2022
