NZ food some of the world's safest

File photo / NZ Herald

New Zealand has one of the safest food supplies in the world, according to a comprehensive study of the chemicals, nutrients and contaminants in common foods.

The five-yearly total diet study, released today involved hundreds of thousands of tests to determine the chemical concentrations in our 123 most commonly eaten foods.

Ministry of Agriculture and Forestry acting policy manager Cherie Flynn said it found the New Zealand diet posed no food safety concerns from chemical residues or contaminants.

"Results from this comprehensive study provide confidence that New Zealand continues to have one of the safest food supplies in the world," she said.

The study allows the ministry to estimate and monitor dietary exposures to chemical residues, nutrients and contaminants across eight age-gender groups, and can reveal trends that influence food safety strategies.

Across all eight age-gender groups, estimated dietary exposures to 241 agricultural chemical residues were well below acceptable daily intakes, with 99 per cent at less than 0.1 per cent of acceptable daily intakes.

"Although we are getting more residue detections than in the past because more sophisticated testing equipment can pick up residues at levels well below what we've been picked up in our previous total diet studies, it is very pleasing to see that the actual levels found are trending down," Ms Flynn said.

Testing for contaminants including lead, mercury, methylmercury, cadmium and arsenic also showed no cause for concern.

Lead levels were likely to be as low as achievable, while cadmium levels were below monthly intake levels set by the World Health Organisation (WHO).

Estimated exposures to mercury and methylmercury were also below the WHO's weekly intake levels, but people who ate a lot of fish - particularly large predatory fish like marlin - had the potential to have higher exposures.

Nutrient testing found sodium intakes exceeded healthy levels in six of the age-gender groups by 116 per cent to 148 per cent.

Only the diets of women aged over 25 were below this level, but their intakes were still two to fours times higher than healthy levels.

Ms Flynn said although dietary intakes of sodium were high, it was positive that trend data showed it slowly decreasing in some groups.

"It's also important to note the great progress the food industry is making in voluntarily reducing sodium in many of the key food categories that contribute the most to people's sodium intake."

Scientists from the Institute of Environmental Science and Research carried out 250,000 analyses on 4330 individual food samples.

The foods were prepared for eating, such as peeling bananas or cooking meat, before they were tested.

The 2009 total diet survey was the seventh conducted in New Zealand since 1974/75.

The WHO supports total diet studies as one of the most cost-effective ways of determining whether people were exposed to potentially unsafe levels of toxic chemicals through food.