Nudging plant-based alternatives to meat and dairy in a real-life online supermarket: A randomized controlled trial

Can (dynamic) social norms encourage plant-based food purchases? a quasi-experimental study in real-world Dutch supermarkets

BACKGROUND

Communicating (dynamic) social norms is considered a promising tool to stimulate healthy and sustainable food choices. The aim of the present study was to evaluate to what extent a (dynamic) social norm intervention in real-world supermarkets could increase sales (grams per week) of meat alternatives (i.e. meat substitutes and legumes).

METHODS

A quasi-experimental study, including three intervention and three control supermarkets, was conducted during a 12-week period. The intervention supermarkets communicated dynamic norms textually on stickers and banners at different in-store locations (e.g. at the entrance, meat aisles). Moreover, the prominence of meat substitutes was (optically) increased and legumes were conveniently placed near the meat and meat substitutes section. Weekly sales data over a period of 75 weeks were obtained, 62 pre-intervention and 13 during intervention. Comparative interrupted time series analyses were conducted to analyse changes in meat alternative sales (in grams) during the intervention period in the intervention supermarkets compared to pre-intervention sales trends and to control supermarkets. Secondary outcomes included meat sales in grams per week and the ratio of protein content of meat alternatives to protein content of meat sales.

RESULTS

Average meat alternative sales in weekly grams before the intervention were M = 371,931.2 (SD = 113,055.3) in the control supermarkets and M = 299,012.5 (SD = 91,722.8) in the intervention supermarkets. The intervention did not change meat alternative sales in intervention supermarkets compared to pre-implementation sales trends and to control supermarkets (B = - 685.92, 95% CI [- 9904.8; 8525.7]). Sales of meats were also unaffected (B = - 130.91, 95% CI [- 27,127.50; 26,858.33]), as well as the ratio of protein content of meat alternatives to protein content of meat in grams sold per week (B = - 670.54, 95% CI [- 8990.6; 7644.4]).

CONCLUSIONS

Communicating (dynamic) social norms via textual and environmental cues (i.e. increasing the prominence of meat alternatives in supermarkets) did not increase meat alternative sales nor reduce meat sales. With supermarkets playing an important role in modulating sustainable food choices, more substantial effort or changes are needed to increase plant-based food purchases and lower meat purchases.

Vegetarian, vegan, or plant-based? Comparing how different labels influence consumer evaluations of plant-based foods

Market actors have a role to play in enabling sustainable food transitions. One challenge for these actors is how to promote plant-based foods in ways that appeal to a growing number of consumers. Here we test how different plant-based related labels affect consumer appraisals of a range of foods (cookies, sausages, cheese, chocolate, pasta). In two studies (pre-registered; NUSA = 1148, NGermany = 491), we examined the effects of a 'vegetarian', 'vegan', or 'plant-based' label (compared to no label) on five attributes (healthy, tasty, ethical, pure, environmentally friendly) related to the products. We also measured self-reported likelihood to purchase the products. Overall, the results indicated that the 'plant-based' label was slightly more appealing to participants than the 'vegetarian' and 'vegan' labels. However, contrary to our expectations, neither consumers' information-seeking tendencies nor their pre-existing attitudes toward plant-based foods influenced (i.e., moderated) the effects of the labels. Anticipated taste was a strong and consistent predictor of purchase likelihood for all labeled products, but the ethical and pure attributes also accounted for unique variance in this outcome variable. Taken together, our findings and discussion provide insights into the role of labels and label terminology on consumer appraisals of plant-based foods.