Voluntary health star nutrition ratings on packaged foods introduced a decade ago have likely led to minimal health gains for New Zealanders, a new modelling study has found.
The ratings were introduced in New Zealand and Australia in 2014 to allow consumers to compare similar packaged foods and choose healthier options. The voluntary scheme rates the overall nutritional profile of packaged foods from half a star (less healthy) to five stars (most healthy) and is jointly supported by the New Zealand government, and the Australian and state and territory governments.
Dr Cristina Cleghorn
Research led by Dr Cristina Cleghorn from the Department of Public Health at the University of Otago, Wellington – Ōtākou Whakaihu Waka, Pōneke, estimated whether the scheme was improving New Zealanders' health by prompting manufacturers to reformulate their products to gain better health star ratings.
The research is published today in the Journal of the Royal Society of New Zealand.
Modelling indicated the scheme had led to small changes in people's diets, with sodium intake reduced by 18 milligrams per person per day, and fibre intake up 0.04 grams per person per day.
This corresponds to a small health gain (700 health-adjusted life years) over the lifetime of the population at a net cost to the health system of $8.4 million. This includes the cost of the governance and operation of the system as well as monitoring, evaluation, social marketing and education.
Dr Cleghorn says the voluntary nature of the scheme limits its impact on health outcomes, with recent research showing only about 30 per cent of eligible foods in New Zealand display health star ratings.
"Under the voluntary scheme, the health star labels are mainly displayed on healthier products, with research in New Zealand finding products that displayed the labels had higher star ratings than the estimated ratings for products that did not display the stars."
The number of stars is calculated based on the energy, saturated fat, total sugar, sodium, fruit, vegetable, nut and legume levels of the food and in some cases, the protein and fibre content.
Previous international research has found labelling schemes in other countries have prompted food manufacturers to reduce sodium and artificial trans-fats in foods.
The New Zealand research found there had been minimal reformulation of products in response to the health star labelling scheme, resulting in only small changes to people's dietary intakes, with correspondingly small health gains.
Professor Cliona Ni Mhurchu
Co-researcher, Professor Cliona Ni Mhurchu from the University of Auckland | Waipapa Taumata Rau, says the research shows that if the New Zealand scheme was made mandatory, and the health star ratings were applied to all eligible products in the same food groups, the health gains resulting from reformulation would increase to 24,300 health-adjusted life years and there would be savings to the health system of $568 million.
"Switching from the current voluntary scheme to a mandatory one shifts the scheme from incurring a small net cost to saving the health sector money and is estimated to increase health gains by a factor of 35.
"But the gains are still low, relative to other possible powerful policy interventions, such as a fruit and vegetable subsidy combined with a sugar tax."
Dr Cleghorn says it remains uncertain as to whether a mandatory health star rating scheme would have any impact on the level of calories people consumed and on reducing the risk of obesity.
"Our research suggests making the health star ratings mandatory would result in some health improvements, but there are still a lot of uncertainties around that."
The study is the first to use real-world New Zealand data on reformulation of the food supply resulting from health star ratings to estimate changes in health outcomes.
The research paper, 'Estimated health impacts of reformulation resulting from Health Star Rating nutrition labelling in Aotearoa New Zealand' is published in the Journal of the Royal Society of New Zealand and can be read here: https://doi.org/10.1080/03036758.2025.2455499
The research was funded by a Health Research Council of New Zealand programme grant (18/672).
