22nd Australian Total Diet Study  

A total diet study of five trace elements: iodine, selenium, chromium, molybdenum, and nickel

Published October 2008

The Australian Total Diet Study (ATDS), formerly known as the Australian Market Basket Survey, is Australia ’s most comprehensive assessment of consumers’ dietary exposure (intake) to a range of food chemicals including food additives, nutrients, pesticide residues, contaminants and other substances. The survey has been conducted approximately every two years, and this is the 22^nd such survey.

Past studies have consistently shown that Australian dietary exposures to pesticide residues and contaminants are well below Australian or international reference health standards and do not represent a public health and safety risk. Therefore, the scope and format of the study has been broadened to include a wider range of chemicals found in food, including additives and nutrients. This change has allowed Food Standards Australia New Zealand (FSANZ) greater flexibility in focusing the study on specific food chemicals where further data on dietary exposure (intake) are desirable. The 22^nd ATDS estimated the dietary intake of the Australian population of five nutrient trace elements, namely iodine, selenium, chromium, molybdenum and nickel. Representative foods likely to contain these nutrients were sampled and prepared to a ‘table-ready’ state before analysis, in order to provide realistic estimates of amounts of the nutrients in the food as consumed.

As for the past three total diet studies (19^th to 21^st), food consumption data derived from the 1995 National Nutrition Survey were used in the calculation of dietary intakes of the nutrients.

This study provides valuable data that can be used for developing or amending food regulatory measures to ensure the protection of public health and safety. In particular, the results for iodine support previous findings in relation to iodine deficiency and consequently, FSANZ will be introducing mandatory fortification of iodine in bread, from September 2009, to enhance public health.

Government food agencies in each State and Territory have provided invaluable assistance with this study and FSANZ acknowledges their very important contribution. A formal international expert peer reviewer was also engaged to evaluate the study and provided useful detailed comments.

The Study

The purpose of the Australian Total Diet Study (ATDS) is to estimate the level of dietary exposure (intake) of the Australian population to a range of chemicals including pesticide residues, contaminants, nutrients, additives and other substances that may be found in the food supply. The 22nd ATDS estimated dietary intake of five nutrient trace elements: iodine, selenium, chromium, molybdenum and nickel. Dietary intake was estimated by determining the level of the nutrient in foods by laboratory analysis, and then combining this with the amount of food consumed, as determined in the 1995 National Nutrition Survey (NNS). The dietary intake of the nutrients was assessed against their respective reference health standard for Australian population groups, where available. In order to achieve more accurate dietary intake estimates, the foods examined in the ATDS were prepared to a ‘table ready’ state before they were analysed. As a consequence, both raw and cooked foods were examined. [ continued ]

Results

The estimated dietary intake of each nutrient from the Australian diet was compared to the relevant Australian Estimated Average Requirements (EAR) or Adequate Intake levels (AI) and the Upper Level of Intake (UL) endorsed by the National Health and Medical Research Council (NHMRC) in 2006 .concentrations of each nutrient in each food analysed were determined. The 5th percentile, mean and 95th percentile levels of dietary intake were calculated for each nutrient and population group, based on the mean nutrient concentration. [ continued ]

Conclusion

Whilst the majority of Australians had dietary intakes approaching or above the EAR or AI for selenium, molybdenum and chromium, a substantial proportion of the population had iodine intakes below the EAR. FSANZ has subsequently commissioned further analyses of iodine levels in Australian foods and will be introducing mandatory fortification of iodine in bread, from September 2009.

Continued monitoring of selenium concentrations and intakes may be warranted given the lower levels found in a range of foods compared to the findings of the 20^th ATDS. Selenium has been included in the 23^rd ATDS.

There were no concerns about excessive dietary intake of the nutrients assessed against established reference values, where these exist.

Full colour version report

Appendix 1: Glossary of terms
Appendix 2: Foods sampled in the 22nd ATDS
Appendix 3: Food preparation instruction
Appendix 4: Summary of Analytical Methods
Appendix 5: Mean, minimum and maximum levels of nutrients in foods
Appendix 6: Dietary modelling techniques used to estimate trace element
Appendix 7: Mapping
Appendix 8: Mean food consumption (consumers only)
Appendix 9: Estimated intakes of each nutrient for lower, middle and upper bound mean analytical levels
Appendix 10: Percent contribution of foods to total trace element
Appendix 11: Number of respondents for each age-gender group assessed
Appendix 12: Number of respondents above and below NRV levels for each age-gender group assessed
Appendix 13: Comparison of selenium levels (µg/kg) found in the 20th (2000-2001) and 22 ATDS (2004)