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Summary - What is Iodine?This answer is brought to you by many of the Australian nutrition professionals who regularly contribute to the Nutritionists Network ('Nut-Net'), a nutrition email discussion group. Iodine is a chemical element that is required for growth and survival. It is found in varying amounts in plants and animals, and the quantity we obtain from plants depends on the concentration of iodine in the soils in which they were grown. The richest natural food sources of iodine are seafood and seaweed (such as kelp and nori), because the ocean is a rich reservoir of iodine. Two or three serves a week of seafood will provide sufficient intake of iodine. Although generally lower than in most seafoods, the iodine levels in foods of animal origin (eggs, meat and dairy products) are higher than in most foods of plant origin, and they may have been further enriched by the use of iodine-supplemented animal feed. Adults need about 150 micrograms of iodine per day (200 micrograms if pregnant or breastfeeding). Children and infants have somewhat lower requirements. Iodine’s most important known function is as a component of thyroid hormones, which play a vital role in the regulation of metabolic processes such as growth and energy expenditure. These hormones are essential throughout childhood for normal brain and physical development. They are also critical for normal development of the baby in the womb, so for women who plan to become pregnant, iodine intake is one of the important nutritional factors they need to take into account. People who do not get adequate iodine in their diet may develop a condition known as ‘goitre’, a swelling of the thyroid gland in the neck. Iodine deficiency can also lead to weight gain, lethargy, intolerance to cold, increased blood cholesterol, mental slowness and reduced heart function. Several areas of Australia and New Zealand have soils that are low in iodine. Recent research findings suggest that mild iodine deficiency may be a widespread problem in the general population. Any salt used at home should be iodised salt (that is, iodine has been added). Note that sea salt is a poor source of iodine. Supplements of iodine may be an important source for individuals who do not eat seafoods, animal flesh, animal products, or iodised salt, or who have a greater requirement for iodine (such as pregnant or breastfeeding women). Although most individuals can tolerate a wide range of iodine intake, exposure to extremely high levels (above 1,000 micrograms per day) is potentially harmful. Use only those tablets that state the iodine content on the label, so you know how much you are getting. And check first with your doctor that the iodine content of the supplement is appropriate. Because health authorities recommend minimising salt intake (largely to reduce the risk of high blood pressure) any lack of iodine in the general diet should not be overcome by recommending that people eating more iodised salt. Rather, adding iodine to some of the more widely consumed and health-promoting foods may be a better option. In Tasmania, a voluntary program is being trialled whereby commercial bread manufacturers are encouraged to use iodised salt in baking. Other possible options include iodising flour or iodising dairy products and dairy alternatives. Click here for full FAQ on Iodine. Back to Frequently Asked Questions Index |