At the request of the then Australia and New Zealand Food Regulation Ministerial Council (the Ministerial Council), Food Standards Australia New Zealand developed mandatory fortification requirements for folic acid and iodine to address two important public health issues: to reduce the prevalence of neural tube defects (NTDs) (serious birth defects) in Australia, and to deal with the re-emergence of iodine deficiency in both Australia and New Zealand. These mandatory requirements were accepted in 2007 and became effective as part of Standard 2.1.1 Cereals and cereal products in the Australia New Zealand Food Standards Code (the Code) from September-October 2009.
In agreeing to the Code changes, the Ministerial Council asked that a comprehensive and independent review be initiated 2 years after their implementation, and that the Food Regulation Standing Committee and the Australian Health Ministers' Advisory Council oversee the review process. The three-stage review comprises an assessment of:
- food industry compliance and impacts on enforcement agencies
- population health effects of mandatory folic acid and iodine fortification
- the effectiveness of the mandatory folic acid and iodine fortification initiatives.
This report is the second stage of the review, focusing on the population health effects of mandatory folic acid and iodine fortification. It assesses changes in nutrient intake, nutrient status and health effects before September 2009 (pre-mandatory fortification) and after September 2009 (post-mandatory fortification), where data sources permit.
These mandatory requirements have resulted in increases in the level of folic acid and iodine in the food supply, and subsequent increases in nutrient intakes and nutrient status.
Post-mandatory folic acid fortification in Australia, there was a statistically significant 14.4% decrease in the rate of NTDs in the total study population (the total study population included New South Wales, Queensland, Western Australia, South Australia and the Northern Territory; data were not available or of sufficient quality from Victoria, the Australian Capital Territory and Tasmania) (10.2 to 8.7 per 10,000 conceptions that resulted in a birth). Omitting New South Wales residents (where data on NTDs are less complete), there was a non-significant 12.5% decrease in NTDs (12.8 to 11.2 per 10,000 conceptions that resulted in a birth). The reduction in NTD rates in these populations is in keeping with that predicted during the development of the mandatory fortification requirement.
The decrease in NTDs was most substantial for Aboriginal and Torres Strait Islander women and teenagers. There was a 74.2% decrease in the rate of NTDs among Indigenous women in the total study population (from 19.6 to 5.1 per 10,000 conceptions that resulted in a birth) and an 80.2% decrease among Indigenous women in the population omitting New South Wales residents (from 22.8 to 4.5 per 10,000 conceptions that resulted in a birth). These results were statistically significant.
There was a 54.8% decrease in the rate of NTDs among teenagers in the total study population (from 14.9 to 6.7 per 10,000 conceptions that resulted in a birth) and a 62.6% decrease among teenagers in the population omitting New South Wales residents (from 18.6 to 7.0 per 10,000 conceptions that resulted in a birth). These results were statistically significant.
Sensitivity analysis was undertaken using data that omitted New South Wales residents from the total study population to assess the potential bias of missing data from the state. The analysis showed that including New South Wales data provided a much larger population and improved the study power. The level of NTD ascertainment (detection) in New South Wales has been shown to be generally consistent over time, allowing the use of these data to assess changes in NTD rates.
These results should be considered in the context of the short study period post-fortification and the relative rarity of NTDs, both of which contribute to variability in NTD rates. Australian NTD rates need ongoing monitoring to confirm whether these reductions will be sustained.
Post-mandatory iodine fortification in Australia, the population was consuming sufficient iodine to address the recent re-emergence of mild iodine deficiency at a population level. Median urinary iodine concentration (MUIC)—a measure of iodine status—for the general population was 131 µg/L, within the range of adequacy (100 to 199 µg/L). Children aged 5–8 had the highest MUIC (175 µg/L) and women aged 16–44 had a lower MUIC (121 µg/L). Intakes for pregnant women aged 16–44 (116 µg/L) were still inadequate to meet their increased requirements during pregnancy and breastfeeding.
Post-mandatory iodine fortification in New Zealand, there was a modest improvement in iodine intakes; however, some groups were still at risk of mild iodine deficiency. The MUIC for adults aged 18–64 was 73 µg/L and for women aged 18–44 was 68 µg/L, indicative of mild iodine deficiency. The MUIC for children aged 8–10 was 113 µg/L, which was within the range of iodine adequacy, but thyroid hormone levels suggest marginal risk of inadequacy.
Preliminary material: Acknowledgments; Abbreviations; Symbols
1.1 Folic acid
1.3 Baseline data for monitoring mandatory fortification
1.4 Nutrient reference values for folic acid and iodine intakes
1.5 Biomedical reference values for folic acid and iodine status
1.6 Data sources used in this report
1.7 Structure of this report
2 Mandatory folic acid fortification in Australia
2.1 Food composition
2.2 Food industry compliance
2.3 Nutrient intake
2.4 Nutrient status
2.5 Health benefits
2.6 Adverse health effects
3 Mandatory iodine fortification in Australia
3.1 Food composition
3.2 Food industry compliance
3.3 Nutrient intake
3.4 Nutrient status
3.5 Health benefits
3.6 Adverse health effects
4 Mandatory iodine fortification in New Zealand
4.1 Food composition
4.2 Food industry compliance
4.3 Nutrient intake
4.4 Nutrient status
4.5 Health benefits
4.6 Adverse health effects
5.1 Mandatory folic acid fortification in Australia
5.2 Mandatory iodine fortification in Australia
5.3 Mandatory iodine fortification in New Zealand
5.4 Next steps
Appendix A: Government committees with oversight of the mandatory folic acid and iodine fortification requirements
Appendix B: Monitoring framework for mandatory fortification
Appendix C: Reference values for monitoring folic acid and iodine
Appendix D: Information on selected data sources
End matter: References; List of tables; List of figures