Furthermore, shoppers who view label information are significantly more likely to buy the healthier item, with on-pack information found to be checked for around one-fifth of all purchases.
The study also found that shoppers were most likely to view labels on packaged foods where nutrition composition is heterogeneous and ambiguous.
The New Zealand Starlight study — a collaboration between the National Institute for Health Innovation, University of Auckland and the Department of Public Health, University of Otago — was a four-week randomised, controlled trial of the effects of three different types of nutrition labels on consumer food purchases: Traffic Light Labels, Health Star Rating labels, or Nutrition Information Panels.
Smartphone technology allowed participants to scan bar codes of packaged foods and receive randomly-allocated labels on their phone screen, and to record their purchases. The app, therefore, provided objectively-recorded data on label-viewing behaviour and food purchases.
Over the four-week intervention, the 1,255 participants viewed nutrition labels for 23% of all purchased products. The frequency analysis of the total of 23,189 products for which the labels were viewed showed that the food groups people viewed labels most often for were dairy (17.3% total views), bread and bakery (16.3%), packaged fruit and vegetables (13.1%), cereals (11.9%) and sauces and spreads (8.2%).
They were least likely to view labels for sugar and honey products, eggs, fish, fruit and vegetables, and meat.
The purchases by food group were similar to the label-viewing patterns in terms of ranked order and proportional contributions to total purchases. Food groups purchased most often, irrespective of label-viewing behaviour, were dairy (17.2% total purchases), bread and bakery (15.5% purchases), packaged fruit and vegetables (13.8%), cereals (11.3%) and sauces and spreads (8.1%).
According to the study, the main trial analysis found no difference in the type of label use.
To enhance consumer understanding of the composition of packaged foods and to promote healthier food choices, the researchers recommended that specific attention should be paid to the most frequently-viewed food groups when implementing nutrition labelling schemes, particularly voluntary labelling systems, which may be displayed selectively by the industry on only certain products.
One noticeable factor was that the frequency of use of the labels decreased over time. This was probably because the motivation to use the app in the exercise decreased (possibly out of fatigue or laziness), or that participants learned the nutrition information of commonly purchased items after scanning them once or twice.
It could also point to the fact that healthy eating habits or the motivations behind them are not deeply entrenched, and may need to be reminded, reinforced or encouraged.
“Do nutrition labels influence healthier food choices? Analysis of label viewing behaviour and subsequent food purchases in a labelling”
Authors: Cliona Ni Mhurchu, Helen Eyles, Yannan Jiang, Tony Blakely