Total diet study begins in New Zealand

Posted by Isobel Drake on 21st 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 consumers eat.

Every five or six years more than 120 foods commonly eaten as part of a typical diet are tested to estimate consumer 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,” New Zealand Food Safety Authority (NZFSA) Senior Programme Manager, Cherie Flynn, advised. “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 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 a growing consumer 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 indicate 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,” she noted. “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.”

“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,” Mrs Flynn concluded.

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.