New Zealand's self-regulations around sugary drinks are not working and a sugar tax should be considered, an Otago University study suggests.
The study found people who drank sugary drinks were less likely to make healthy food choices, with an increased likelihood to eat fast food and confectionery. They were also less likely to read food labels.
Otago's Kirsten Robertson said sugary drinks "have little nutritional benefit and are causing our country significant harm".
"New Zealand relies on industry self-regulation and has called for better labelling so individuals can take responsibility for their own sugar intake," she said.
However, the finding that sugary-drink consumers were less likely to read labelling "raises serious questions about the likelihood of them changing their behaviour" if the labelling was to change.
She said sugary drinks in New Zealand were above World Health Organization recommendations for sugar content, therefore "industry self-regulation is not working".
Ms Robertson said taxes on the sugary drink industry would give power back to consumers, without relying on the reading of food labels.
"Findings in other countries suggest national taxes will encourage the industry to reformulate their products by reducing the sugar content and will encourage consumers to select other alternatives," she said.
"Therefore, we support the sugar tax recommendation by the New Zealand Medical Association and the New Zealand beverage guidance panel."
The study surveyed 2000 people and looked at their food and beverage intake over 24 hours. Over 30 per cent consumed sugary drinks and displayed unhealthy eating.