National diet to go under the microscope

The New Zealand Food Safety Authority (NZFSA) has started planning for the 2009 New Zealand Total Diet Survey, when the food we eat is put under the microscope.

Every five or six years more than 120 foods commonly eaten as part of a typical diet are tested to see what else they might contain. The tests look for chemical residues and certain contaminants and nutrients, and provide a snapshot of New Zealanders' exposure to these elements in a typical diet.

NZFSA Senior Programme Manager Cherie Flynn said, "Results are not expected to change significantly from the last survey, conducted in 2003–04, but it will let us see if certain trends are continuing. The two most worrying, from a health perspective, are our high levels of sodium consumption and low levels of iodine.

"With our stringent food safety procedures in New Zealand, residues and contaminants are rarely an issue but without regular testing we can't be confident that our systems are performing as intended."

For the last survey NZFSA undertook additional testing identified in consultation with interested parties. These included analysis for iron and sodium, additional work on iodine, inclusion of an acidic herbicide screen and widening the sampling base with more individual analysis of samples.

"Normally we wouldn't repeat these additional tests but because of the health issues around sodium and iodine, we will be closely monitoring these nutrients. We will maintain the increased sample size we introduced in 2003/04 (which doubled the samples previously taken) and individual sample analysis for almost all foods for each region or national brand that we also began in the last survey", says Cherie.

Once a list of foods to be sampled has been confirmed, sampling officers around the country will go shopping to gather samples. They will do this over four sampling rounds during 2009 to capture seasonal variations.

All foods are then prepared ready for consumption and tested. This process is unique to the total diet survey in that food is tested 'as consumed', meaning bananas are peeled and meat is cooked.

The findings will be used to estimate our total dietary exposure by using simulated diets for a range of different population groups developed with expert advice and using information from the National Nutrition Survey conducted by the Ministry of Health.

Interim quarterly results will be available throughout 2009. More information on the Total Diet Survey is available on NZFSA's website www.nzfsa.govt.nz/science/research-projects/total-diet-survey/index.htm.