Iodine deficiency is the most common preventable cause of mental retardation in the world; obtaining iodine through the food supply is therefore paramount. This article examines a growing frequency of Iodine deficiency in Australia. Submitted by our member Dr Ben Balzer, a General Practitioner with special interest in nutrition, from Sydney Australia. 

 

The Problem

In 2006, the landmark Australian National Iodine Nutrition Study confirmed the existence of inadequate iodine intake in the Australian population. The cross-sectional survey was of 1709 students aged 8–10 years from 88 schools, drawn from the five mainland Australian states of New South Wales, Victoria, South Australia, Western Australia and Queensland. The study found that Overall, children in mainland Australia are borderline iodine deficient, with a national median UIE of 104 μg/L. 

Why? 

The NINS study indicates two factors that have caused the decline in iodine intake in Australia. 

  1. Changes within the dairy industry, with chlorine-containing sanitisers now replacing iodine-containing sanitisers. Iodine released from these chemicals into milk has been the major source of dietary iodine in Australia for at least four decades, but is now declining.
  2. The decreasing consumption of iodised salt. Few, if any, food manufacturers use iodised salt in the preparation and manufacture of foods.

The Solution - USI

Expert groups such as WHO UNICEF & ICCIDD recommend Universal Salt Iodisation (USI) for all countries. Since 1999, The Australian Centre for the Control of Iodine Deficiency Disorders has been raising the alarm and recommending USI for Australia. 

Food Standards ANZ (FSANZ) have been looking at iodine since 2003. However, they struck a problem with the definition of adequate guidelines for iodine intake and fortification. 

Read Their Report

When FSANZ looked at changing the food supply, they not only look at the problem of deficiency, but also they look at upper limits that might cause problems. This meant, the guideline for intake was an upper limit rather than a recommended daily intake. Accordingly FSANZ went ahead with a recommendation to iodise the salt in bread alone. 

This approach has been tried in Tasmania, and proven unsuccessful - particularly in providing adequate iodine for pregnant women.

Burgess et al (2007) assessed the impact of iodine fortification of bread on the iodine status of pregnant women in Tasmania. For pregnant women, the WHO recommends an Iodine intake of 150–249 μg/L measured through Urinary Iodine Concentration (UIC). Studying 285 women attending the Royal Hobart Hospital (RHH) antenatal clinic, they found Iodine deficiency in pregnancy persists despite being corrected in Tasmanian children. Before supplementation, the median UIC of the 285 women attending the RHH antenatal clinic was 76 μg/L. After supplementation, median UICs were 81 μg/L for 288 women attending primary health care centres and 86 μg/L for 229 women attending the RHH antenatal clinic. 

Iodine Deficiency Worldwide Source: thyroidmanager.org

Iodine Deficiency Worldwide, Source: thyroidmanager.org

 

The Way Forward

Burgess et al concluded that successful iodine supplementation must target reproductive-age and pregnant women and be substantiated by ongoing monitoring during pregnancy and lactation. They go on to argue that iodine fortification in bread is not enough, and Universal Salt Iodisation should be the preferred national solution. 

To this end, Iodine Australia New Zealand has composed this Memorandum of Understanding to provide a focal point to solving the problem, and facilitating the implementation of USI.

References 

Li M, Eastman CJ, Waite KV, Ma G, Zacharin MR, Topliss DJ, Harding PE, Walsh JP, Ward LC, Mortimer RH, Mackenzie EJ, Byth K, Doyle Z. Are Australian children iodine deficient? Results of the Australian National Iodine Nutrition Study. The Medical Journal Of Australia 2006; 184:165-169.

Burgess JR, Seal JA, Stilwell GM, Reynolds J, Taylor ER, Parameswaran V. A case for universal salt iodisation to correct iodine deficiency in pregnancy: another salutary lesson from Tasmania. The Medical Journal Of Australia 2007; 186:574-576.

Food Standards Australia New Zealand. Initial Assessment Report, Proposal P230 Iodine Fortification. Canberra: FSANZ, 2004.