How should sugar-sweetened beverage health warnings be designed? A randomized experiment

Health warnings are a promising strategy for reducing consumption of sugar-sweetened beverages (SSBs), but uncertainty remains about how to design warnings to maximize their impact. Warnings already implemented in Latin America use nutrient disclosures, while proposed U.S. warnings would describe the health effects of consuming SSBs. We sought to determine whether warning characteristics influence consumers' reactions to SSB health warnings. A national convenience sample of U.S. adults (n = 1360) completed an online survey in 2018. In a factorial design, we randomly assigned participants to view SSB health warnings that differed in: 1) inclusion of health effects ("Drinking beverages with added sugar contributes to obesity, diabetes, and tooth decay"); 2) inclusion of a nutrient disclosure ("High in added sugar"); 3) inclusion of the marker word "WARNING;" and 4) shape (octagon vs. rectangle). The primary outcome was perceived message effectiveness (PME, range 1-5). PME was higher for warnings that included health effects (average differential effect [ADE] = 0.63, p < 0.001) or nutrient disclosures (ADE = 0.32, p < 0.001) compared to warnings without this information. However, adding a nutrient disclosure to a warning that already included health effects did not lead to higher PME compared to warnings with health effects alone. The marker "WARNING" (ADE = 0.21) and the octagon shape (ADE = 0.08) also led to higher PME compared to warnings without these characteristics (ps < 0.001). The same pattern of results held for the secondary outcomes, fear and thinking about harms. SSB health warnings may have more impact if they describe health effects, use the marker "WARNING," and are octagon-shaped.