A just-released University of Otago study highlights the need for stronger Government action over sugary drinks, to counter New Zealand's obesity epidemic.
"We're the third most overweight nation in the OECD and have to do something about this,'' study first author Dr Kirsten Robertson says.
Dr Robertson, an Otago senior lecturer in marketing, said sugar-sweetened beverages (SSBs) were "extremely high in sugar'', and drinking them was a significant problem in New Zealand.
A standard 355ml can of soft drink could contain around 10 or so teaspoons of sugar, she said.
Adults gained 17% of their overall sugar intake from SSBs, she said.
The drinks had little nutritional benefit and were a leading cause of obesity, tooth decay, and type 2 diabetes.
But the study, based on a national survey of more than 2000 people, found people who drank SSBs were less likely to try to eat healthily and also less likely than non-SSB drinkers to read food labels.
SSB drinkers were also more likely to eat fast food and confectionery.
The study, published in international journal PeerJ, focused on people's food and beverage intake over a 24-hour period and self-reported their intentions to eat healthily.
Of those surveyed, 30.5 percent had consumed SSBs in the past 24 hours.
They also showed a general pattern of unhealthy eating as they also consumed dessert, confectionery, fast food and pre-prepared food, and were less likely to eat breakfast or a meal made from scratch.
Several other countries, including the United Kingdom, had successfully implemented national taxes on SSBs, but New Zealand still relied on industry self-regulation and had urged better labelling so individuals could take responsibility for their own sugar intake.
But the fact that SSB consumers were less likely than non-SSB consumers to try to eat healthily, or to read food labels, raised "serious questions'' about if better labelling would help change their behaviour, she said.
Past research showed the sugar content in SSBs in New Zealand exceeded WHO recommendations, and industry self-regulation was not working.
Sugar taxes in the UK had not adversely affected big business, which had simply reduced the sugar content of drinks to avoid the tax.
"Therefore, we support the sugar tax recommendation by the New Zealand Medical Association and the New Zealand beverage guidance panel,'' she said.
Given SSB consumers were less likely to read food labels, national taxes would "give some power back'' to those people to "make healthier choices without having to refer to food labels'', she said.