New Zealand fast food contains considerably more salt than similar meals in Europe, a Canadian study has found.
The study, published in the Canadian Medical Association Journal and undertaken by researchers in Australia, Canada, France, New Zealand, the United Kingdom and the United States, looked at the salt content of 2124 food items on the menu at Burger King (Hungry Jack's in Australia) Domino's Pizza, Kentucky Fried Chicken (KFC), McDonald's, Pizza Hut and Subway.
Comparisons were made between the salt content in savoury breakfast meals, burgers, chicken products, pizza, salads, sandwiches and French fries.
Despite the restaurants chains all being owned by multi-national corporations, salt levels differed widely between countries, with sodium levels in France and the UK markedly lower than the other countries.
The study found New Zealand fast foods on average contained 8 per cent more sodium than comparable foods in the UK and 18 per cent more than equivalent meals in France.
A McDonald's Big Mac in New Zealand, for example, has 30 per cent more sodium per 100 grams than either France or the UK.
The overall results for New Zealand's fast foods were similar to those of Australia, with the sodium content amounting to an average of 1.3 grams per 100 grams, compared with 1.2 in the UK and 1.1 in France.
The figures for Canada and the US were even higher than those in New Zealand, with sodium levels in Canada averaging 27 per cent more than in France, at 1.4 grams per 100 grams and US levels at 36 per cent more than France, at 1.5 grams per 100 grams.
A diet high in sodium leads to higher blood pressure, and to a greater risk of heart disease and stroke. Fast foods such as pizza and burgers are a leading source of excess dietary sodium.
New Zealanders have an average salt intake of nine grams a day, compared with the recommended maximum of five to six grams a day.
One of the researchers involved in the study, associate professor Cliona Ni Mhurchu from the University of Auckland's Clinical Trials Research Unit, said the study gives an "urgent message about the need for change".
"If the UK and France have similar products with much lower salt levels, this shows that New Zealand could be - and should be - heading in the same direction.
"In the UK there is a long-standing programme where agreements between government and industry on salt targets have driven down the salt levels of processed food. The study demonstrates there is still clear room for improvement in the UK, and even more so in New Zealand. The research refutes the standard industry protest, since it shows there is no technical reason why salt content of our food can't be reduced."
Dr Norman Campbell, University of Calgary, said the studied showed the failures of fast food companies to decrease salt levels voluntarily.
"Canadian companies indicate they have been working to reduce sodium but the high sodium in these foods indicates voluntary efforts aren't working," Dr Campbell said.
"These high levels indicate failure of the current government approach that leaves salt reduction solely in the hands of industry. Salt reduction programs need to guide industry and oversee it with targets and timelines for foods, monitoring and evaluation, and stronger regulatory measures if the structured voluntary efforts are not effective."