Effect of different front-of-package food labels on identification of unhealthy products and intention to purchase the products– A randomised controlled trial in South Africa

Abstract

This study aimed to evaluate the effect of different labels on participants identifying products high in nutrients of concern; identifying unhealthy products, and intention to purchase unhealthy products. This blinded randomised controlled trial included a representative sample of South African households (n = 1951). Per household we selected a member primarily responsible for food purchases. Participants were randomised into the Warning Label (WL), Guideline Dietary Amounts (GDA) or Multiple Traffic Light (MTL) arms. Each participant answered questions in a no label condition (control) followed by same questions in the label condition (experiment). Complete data were collected and analysed for 1948 participants (WL = 33.7%, GDA = 32.1% and MTL = 34.2%). The probability of correctly identifying products high in nutrients of concern and identifying products as being unhealthy was higher with the WL compared to the GDA or MTL for most items. There was no difference in performance between the GDA and the MTL when considering all items together. A higher percentage of participants reported a lower intention to purchase an unhealthy product after exposure to the WL compared to MTL for 5 out of 6 products; 2 out of 6 products for the WL compared to GDA and 2 out of 6 products for GDA compared to MTL. Compared to the control condition, exposure to each of the labels resulted in better identification of nutrients of concern, unhealthy products and a lower intention to purchase when considering all specific outcome items together. The WL showed a higher potential to enable South African consumers to identify products high in nutrients of concern, identify unhealthy products and discourage purchasing of unhealthy products.