Choosing a front-of-package warning label for Brazil: A randomized, controlled comparison of three different label designs

Introduction: Warning labels (WLs) are the newest paradigm of nutrient-based, front-of-package labels (FOP) that have been consistently shown to be more effective at informing consumer purchases than other FOP labels. Their effectiveness may be attributed to their design and the consistency in the information they communicate. The present study assessed designs effects of WLs in improving understanding and perceptions among 2419 Brazilian adults. Methods: Participants were randomly assigned to one of four study arms in an online, randomized, controlled experiment: (1) the Triangular WL 'A lot of /Muito' (Muito); (2) Triangular WL 'High in/Alto em' (Alto); (3) the Chilean WL 'High in/Alto em' (Chile); and (4) a control condition (no WL). Participants responded to a series of questions, while viewing images of 9 products, that assessed their understanding of the nutrient content of the product, its healthfulness, and their intentions to purchase. All aggregate differences in responses between study arms were estimated using oneway-ANOVAs. Results: WLs were superior to the list of ingredients and the nutrition facts panel in improving participant understanding and perceptions of the nutrient profile of products, particularly in helping identify nutrients in excess. Alto was significantly better than the control at identifying which of the two products contained an excess of nutrients and at improving consumer understanding of nutrient content across different indicators. Alto, followed by Muito, was also better at communicating that fewer WLs signified a healthier product. The Muito WL was significantly more visible to participants than the Chile WL. There were no differences between study arms in shifting consumer purchase intentions. Conclusions: In this study, WLs were an important addition to the current nutrition label. The triangular symbol, the white background and the signal word, 'High in/Alto em' showed consistently better results than the signal word 'A lot of/Muito' and the octagonal symbol. These design elements serve to make WLs more visible to consumers, capturing their attention and informing their food evaluations, and may have greater potential to influence appropriate for a Brazilian audience.