Iodine and your thyroid gland
What is iodine?
Iodine is a chemical element that is an essential part of our diet. Foods that are naturally rich in iodine include seafood and plants grown in iodine-rich soil. Unfortunately, the soil in some parts of Australia is iodine deficient, which can result in a low concentration of iodine in food products.
A low intake of dietary iodine can result in iodine deficiency, which is a major worldwide health concern. The World Health Organization's policy of adding iodine to all salt that is for human and animal consumption is one way of preventing iodine deficiency.
Why is an adequate iodine intake important?
Your thyroid gland, which is located in your neck, needs iodine to make thyroid hormones. These hormones control your body's growth and metabolism and are important for the development of the brain in babies and young children. Without sufficient iodine, the thyroid gland is unable to produce an adequate amount of hormones, which can have serious health consequences.
What are the effects of iodine deficiency?
Iodine deficiency can result in a series of conditions, referred to as iodine deficiency disorders. Iodine deficiency disorders can affect people of all ages, but babies are most at risk of serious problems.
Babies who do not receive adequate iodine can have intellectual impairment and problems with physical development. Sometimes, severe mental retardation (sometimes known as cretinism) develops following severe iodine deficiency during early development. In fact, iodine deficiency is the most common cause worldwide of preventable intellectual impairment in children, so it's extremely important for pregnant women, breast-feeding mothers and young children to receive an adequate amount of dietary iodine.
Iodine deficiency can also cause swelling of the thyroid gland (goitre), as well as symptoms of an under-active thyroid gland (a condition called hypothyroidism). Iodine deficiency is the most common cause of hypothyroidism throughout the world. Some of the features of hypothyroidism include:
- tiredness;
- slow heart rate;
- dry skin;
- muscle and joint aches and pains;
- depression;
- constipation; and
- weight gain.
Why has iodine deficiency become more prevalent in Australia?
Iodine deficiency has recently re-emerged as a common problem in Australia. This is due to several factors, including:
- a reduction in the use of iodised table salt at home — it is estimated that only about 20 per cent of households use iodised table salt;
- the food industry rarely using iodised salt; and
- a reduction in the use of iodine in the manufacture of dairy products. (Previously, iodine was widely used in the sterilisation of milk vats, resulting in small quantities of iodine being found in dairy products.)
It has been reported that at least 50 per cent of pregnant women in Australia have an inadequate intake of iodine. Several studies have also found mild-to-moderate iodine deficiency in school-aged children and adults in Tasmania, New South Wales and Victoria.
How can I ensure that my iodine intake is adequate?
Using iodised table salt (which is packaged with a green label) at home is one of the easiest ways of boosting your dietary iodine intake. It's important to note that regular sea salt is a poor source of iodine. People who don't eat seafood, animal products or iodised salt may need iodine supplements to ensure their intake is adequate.
Pregnant and breast-feeding women should make sure that they eat plenty of iodine-rich foods, because of their increased iodine requirements. Some pregnant and breast-feeding women may need iodine supplements. However, you should check with your doctor before starting iodine supplements because too much iodine can be toxic and can trigger thyroid problems in some people, especially those with a history of thyroid disease.
Last Reviewed: 10 November 2008
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