Despite the Government's refusal to implement a sugar tax, hiking prices has again been shown to be probably the best way to stop people drinking calorie-dense drinks.
A review of prior research by medical charity Cochrane found little evidence for a number of alternative measures.
"The review found that many often-recommended measures have little evidentiary base, with certainty of evidence rated as very low," said Eric Crampton, chief economist at think tank the New Zealand Initiative.
"Interventions in this category included measures like healthier vending machines in workplaces and schools, restrictions on the number of stores selling sugar-sweetened beverages, urban planning restrictions on new fast-food outlets, and menu-board calorie labelling. No studies were found that might provide basis for restrictions on advertising."
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But when sugary drinks are made more expensive, or sugar-free alternatives made cheaper, sales fall, the researchers found.
"The evidence is unequivocal... you put up the price, consumption goes down," NZ Dental Association spokesperson Rob Beaglehole told The AM Show on Thursday.
"You get rid of junk food from schools, consumption goes down. Better sugar labelling is again another way of reducing sugary drink consumption. There's lots of different ways that we can act."
But the Labour-led Government, wary of being labelled as tax-hungry, was elected on a promise of no new taxes in its first term - including sugar taxes.
"David [Clark, Health Minister]'s a great guy, he's got awesome ethics, his moral compass is set in the right direction. I believe in him, we know he's going to do something," said Dr Beaglehole.
"If he's not going to do anything about the sugary drink tax, how about asking for other things? Like, why are we still selling sickness in the form of sugary drinks to kids in schools? Wouldn't it be great to have a water-only policy in schools?"
National ruled out a sugar tax when it was in Government, former Health Minister Jonathan Coleman saying there was "no evidence" they worked.
While the Dental Association has given up trying to get a sugar tax implemented this term, Dr Beaglehole's sure they'll get another bite.
"We do know that they have said they're not going to implement a sugar tax this term, so what we're going to direct is all our efforts to next term, when they get back in."
Current polling suggests that is very likely.
Why the focus on sugary drinks?
The World Health Organization recommends adults consume no more than nine teaspoons of sugar a day, and children only three.
"We know sugary drinks are the number one source of sugar in the New Zealand diet, and the number one reason we get rotten teeth, we get obese, and we get type 2 diabetes, is because of sugar," said Dr Beaglehole, "so sugary drinks, in particular, is what we need to target."
A 2.25l bottle of classic Coca-Cola contains 60 teaspoons of sugar. Even a standard 355ml can has nine.
"If I go home and give me my son a can of Coke, a small can, I'm going to be giving him three days' worth of sugar in one hit," said Dr Beaglehole.
Cochrane didn't actually look at the impact of taxes themselves - that's due in a follow-up review, expected later this year. But in addition to price measures, they found evidence for a number of other potential moves, including:
- easy-to-understand 'traffic light' health labels
- limiting availability in schools
- having water or healthy options as the default drink in kids' menus
- labelling healthy drinks with "smiley‐faced emoticons" and giving kids prizes for choosing them
- and preventing the purchase of sugary drinks with benefit payments.
But the quality of evidence for measures other than price hikes was deemed only low to moderate.
"Rather than providing evidence for policy change, we should view the report as suggesting measures potentially worth trialling within an appropriate experimental framework designed to improve the evidence base," said Dr Crampton.