Iodine is required for the production of the thyroid hormones thyroxine (T4) and tri-iodothyronine (T3), which are best known for their role in metabolism (they control the rate at which calories are burned), and also regulate many other bodily processes.
But most importantly, the thyroid hormones (and consequently iodine) are vital for healthy growth, development and reproduction.
Mothers and babies
Iodine is vital for foetal development, and particularly for central nervous system development. Sadly, inadequate maternal consumption of iodine during pregnancy may lead to irreversible (but preventable) mental retardation.
Maternal iodine deficiency may also contribute to conception difficulties and increase the risk of miscarriage and premature childbirth.
Iodine remains important during the early stages of a child’s life when the central nervous system and brain undergo rapid development and growth, and deficiency at this time may result in impaired intelligence.
Taking an iodine supplement prior to and during pregnancy and breastfeeding helps to ensure that sufficient iodine is available to support a healthy pregnancy and healthy baby.
Children and adolescents
Older children and adolescents also need iodine, and deficiency may contribute to learning disabilities, behavioural problems, poorer school performance and reduced IQ.
Iodine deficiency in adults can cause hypothyroidism (underactivity of the thyroid), symptoms of which may include goitre (swollen thyroid gland), fatigue, breast tenderness, tendency to feel cold, dry skin, hair loss, weight gain (or difficulty losing weight), and poor memory, concentration and alertness.
Getting enough iodine
Bread is now fortified with iodine due to concerns that many Australians don’t get enough iodine from their diets. This is a step in the right direction, but doesn’t entirely address the deficiency problem (for example, a child would need to consume five serves of bread per day to obtain sufficient iodine from bread alone).
Fish such as mackerel, haddock and salmon are beneficial iodine sources, but research also suggests that most Australians don’t consume enough fish. Additionally, pregnant and breastfeeding women are cautioned to limit their fish intake in order to reduce their exposure to heavy metals such as mercury.
Iodised salt is another solution, but health risks are associated with high salt consumption, especially for those with high blood pressure.
Since the seaweed kelp is a rich source of iodine, many people choose to take kelp supplements to help ensure that their iodine intake is adequate.