Iodine is an “essential” trace element and an integral component of thyroid hormones. The thyroid hormones are required for normal growth and development of tissues such as the central nervous system and have a broader role in maturation of the body as a whole. They are important for energy production and oxygen consumption in cells thereby helping to maintain the body’s metabolic rate. Iodine deficiency can result in low metabolism and weight gain.
Yet half of Australia’s population doesn’t get enough Iodine. Iodine deficiency is the most common preventable cause of mental retardation in the world; obtaining iodine through the food supply is therefore paramount. Iodine deficiency has re-emerged in Australia with the introduction of new practices of sanitization in the dairy industry and a decline in use and consumption of iodised salt.
The main symptoms of iodine deficiency are goiter, hypothyroidism and pregnancy related problems.
- Goiter: Without adequate iodine, the thyroid progressively enlarges (develops a goiter) as it tries to keep up with demand for thyroid hormone production. Worldwide, iodine deficiency is the most common cause of thyroid enlargement and goiter. This can cause problems breathing, especially when lying down.
- Hypothyroidism: As the body’s iodine levels fall, hypothyroidism may develop, since iodine is essential for making thyroid hormone. This is the most common cause of hypothyroidism globally.
- Pregnancy Related Problems: Iodine deficiency is especially important in women who are pregnant or nursing their infants. Severe iodine deficiency in the mother has been associated with miscarriages, stillbirth, preterm delivery, and congenital abnormalities in their babies. Children of mothers with severe iodine deficiency during pregnancy can have mental retardation and problems with growth, hearing, and speech. In the most severe form, an underactive thyroid can result in cretinism (a syndrome characterized by permanent brain damage, mental retardation, deaf mutism, spasticity, and short stature). Congenital hypothyroidism due to iodine deficiency is the most common preventable cause of mental retardation in the world. Even mild iodine deficiency during pregnancy, which may be present in some women in Australia, may be associated with low intelligence in children.
An iodine deficiency can also cause symptoms such as fatigue, high cholesterol, lethargy and depression. All consumer breads are now fortified with iodine and folate.
- For Men and Women the RDI is 150 µg/day
- For pregnant Women the RDI is 220 µg/day
- For breastfeeding Women the RDI is 270 µg/day
Factors affecting Iodine Absorption
- The utilisation of absorbed iodine is influenced by goitrogens (found in brassica vegetables such as cabbage, broccoli and brussel sprouts) can interfere with the synthesis of the thyroid hormones.
- Foods containing goitrogenic cyanoglucosides such as sweet potato and maize release thiocyanate that competes with iodide, blocking its uptake by the thyroid.
Tips for increasing Iodine
- The availability of iodine in foods differs in various regions of the world
- Iodine is present naturally in soil and seawater, seaweed is high in iodine
- Losses of Iodine content in food can occur in cooking, avoid boiling or microwaving
- Maintain adequate iodine in your diet by using iodized table salt or fortified breads
- Eat foods high in iodine such as those outlined below, particularly dairy products, seafood, meat, some breads, and eggs
- Since even mild deficiency during pregnancy can have effects on delivery and the developing baby, all pregnant and breastfeeding women should take a multivitamin containing at least 150 μg iodine per day.
High Iodine Foods
|Food||Iodine Content (µg)|
|7g Dried Seaweed||4500|
|0.5 g Himalayan Crystal Salt||250|
|1 cup plain yoghurt||154|
|85g Cod Fish||99|
|1 gram fortified iodised salt||77|
|1 Baked Potato medium||60|
|1 cup cows milk||56|
|85g Turkey Breast||34|
|85g canned tuna||17|
|1/2 cup canned corn||14|
|1 cup strawberries||13|
|1 large Boiled Egg||12|
|28g cheddar cheese||12|