Less meat in the shopping basket. The effect on meat purchases of higher prices, an information nudge and the combination: a randomised controlled trial

Background: Reduced meat consumption benefits human and planetary health. Modelling studies have demonstrated the significant health and environmental gains that could be achieved through fiscal measures targeting meat. Adding other interventions may enhance the effect of a fiscal measure. The current study aimed to examine the effect of higher meat prices, an information nudge and a combination of both measures on meat purchases in a three-dimensional virtual supermarket. Methods: A parallel designed randomised controlled trial with four conditions was performed. Participants (≥ 18 years) were randomly assigned to the control condition or one of the experimental conditions: a 30% price increase for meat (‘Price condition’), an information nudge about the environmental impact of meat production and consumers’ role in that regard (‘Information nudge condition’) or a combination of both (‘Combination condition’). Participants were asked to shop for their household for one week. The primary outcome was the difference in the total amount of meat purchased in grams per household per week. Results: Between 22 June 2020 and 28 August 2020, participants were recruited and randomly assigned to the control and experimental conditions. The final sample included 533 participants. In the ‘Combination condition’, − 386 g (95% CI: − 579, − 193) meat was purchased compared with the ‘Control condition’. Compared to the ‘Control condition’ less meat was purchased in the ‘Price condition’ (− 144 g (95%CI: − 331, 43)), although not statistically significant, whereas a similar amount of meat was purchased in the ‘Information nudge condition’ (1 g (95%CI: − 188, 189)). Conclusion: Achieving the most pronounced effects on reduced meat purchases will require a policy mixture of pricing and informational nudging. Less meat is purchased in a virtual supermarket after raising the meat price by 30% combined with an information nudge. The results could be used to design evidence-based policy measures to reduce meat purchases. Trial registration: The trial was registered in the Netherlands Trial Register identifier NL8628. Registered on 18/05/2020. ICTRP Search Portal (who.int) NTR (trialregister.nl)