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Total Diet Study underway

20 January 2009

Buying has begun for the New Zealand Food Safety Authority’s 2009 Total Diet Study, which takes a detailed look at the food we eat.

Every five or six years more than 120 foods commonly eaten as part of a typical diet are tested to estimate New Zealanders’ exposure to chemical residues, contaminants and selected nutrients.

Sampling officers in Auckland, Napier, Christchurch and Dunedin have begun the first round of shopping trips to their local supermarket and greengrocer for the food items to be tested.

The items are sent to Environmental Science and Research (ESR) in Christchurch for preparation and then to RJ Hill Laboratories in Hamilton for analysis.

"What makes this study unique is that the food is prepared to a table-ready form so potatoes are cooked and bananas are peeled,” says New Zealand Food Safety Authority (NZFSA) Senior Programme Manager Cherie Flynn.

“The foods tested are representative of the general eating habits of most age groups in our population.

“We'll be testing foods eaten by infants, children, teenagers, young men and adults over the age of 25. Typical diets for each group will then be used to estimate New Zealanders’ total dietary exposure to over 250 agricultural compounds, the contaminants arsenic, cadmium, lead and mercury, and the nutrients iodine and selenium.”

The 2009 New Zealand Total Diet Study will also test for methylmercury in seafood and infant formula.

“Organic mercury, particularly methylmercury is significantly more toxic than inorganic mercury,” Mrs Flynn says.

“By specifically analysing for methylmercury we can get a clearer idea of New Zealanders’ exposure to this naturally occurring contaminant, rather than making estimates from total mercury levels.

“Infants are one of the most vulnerable groups in the population, and infant formula is a big part of their diet. We not expect to find significant levels of methylmercury in infant formula, but it is prudent to check,” Mrs Flynn says.

The sampling will be carried out over the next 12 months. Foods will be collected every three months with each food sampled twice over the whole study to capture seasonal variations.

Among the changes to the food list this year is the addition of an Indian takeaway to reflect New Zealanders’ growing fondness for curry. Tap and bottled water will also be tested separately for the first time.

Results are not expected to change significantly from the last study, Mrs Flynn says, but it will let us see if certain trends are continuing.

“The last Total Diet Study highlighted New Zealanders’ high levels of sodium consumption and continuing low levels of iodine compared to people in other countries.

“Iodine levels that are too low irreversibly impair the development of intelligence in children. Low iodine levels in adults are also a concern, with severe cases leading to goitre.

“Fortification of bread with iodine does not become mandatory until September, so we do not expect to see significant change in those trends until the next survey is conducted.”

Thanks to our stringent food safety procedures, residues and contaminants are rarely an issue in New Zealand.

“Previous Total Diet Studies have found our food supply to be as good as any in the world, but we need regular testing to ensure our systems are performing as intended.”

Interim quarterly results will be available throughout 2009 with a final report expected at NZFSA’s conference in September 2010. More information on the New Zealand Total Diet Study or Survey is available on NZFSA’s website www.nzfsa.govt.nz/science/research-projects/total-diet-survey/index.htm.

More information on the list of foods and what they will be tested for is available on the NZFSA website www.nzfsa.govt.nz.

Ends

For further comment, contact: Cherie Flynn, Senior Programme Manager (Policy), 04 894 2572

For more information, contact: Mandy Smith, Advisor (Media Communications), 029 894 2528