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.
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 intellectual disability (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:
- slow heart rate;
- dry skin;
- muscle and joint aches and pains;
- constipation; and
- weight gain.
Causes of iodine deficiency
Iodine deficiency has re-emerged in Australia due to several factors, including:
- a reduction in the use of iodised table salt at home;
- increased consumption of commercially processed foods that contain non-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.)
Getting an adequate iodine intake
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.
Most bread (including rolls, hamburger buns and other bread products) made in Australia is now fortified with iodine. Since October 2009, bread manufacturers have been required to replace regular salt with iodised salt when baking all bread except organic bread and salt-free bread.
People who don't eat seafood, bread, animal products or iodised salt may need iodine supplements to ensure their intake is adequate.
Iodine intake during pregnancy and breastfeeding
Pregnant and breast-feeding women should make sure that they eat plenty of iodine-rich foods, because of their increased iodine requirements. However, dietary iodine is not considered adequate to meet the additional needs of pregnancy – pregnant women require 70 micrograms of iodine per day more than when not pregnant.
The National Health and Medical Research Council (NHMRC) recommends that all pregnant and breast feeding women (and women planning a pregnancy) take a supplement containing 150 micrograms of iodine each day.
Women who have a pre-existing thyroid condition should check with their doctor before starting iodine supplements, because too much iodine can be toxic and can trigger thyroid problems in those with a history of thyroid disease.
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5. World Health Organization (WHO). Iodization of salt for the prevention and control of iodine deficiency disorders (updated 14 Nov 2014). http://www.who.int/elena/titles/salt_iodization/en/# (accessed Dec 2014).