Impact of a Default Nudge Intervention on Plant-Based Milk Consumption in a UK University Café

Encouraging plant-based food consumption among western consumers is vital for reducing the environmental impacts of animal agriculture. This study examined whether a default nudge intervention increased plant-based milk consumption in a UK university café using an ABAB experimental design. During the intervention phases, the default milk option was changed from dairy to oat milk. In the first intervention phase, customers were approximately three times more likely to consume plant-based milk when oat milk was the default option (from 16.6% to 51.9%). However, this effect was smaller in the second intervention phase compared to the first (from 51.9% to 46.0%), questioning the intervention’s long-term impact. Comparable data in the university’s second café (where no intervention occurred) found no differences in plant-based milk intake during the study period, suggesting that changes in plant-based milk consumption were due to the default nudge. Based on this intervention, the milk-based carbon footprint per drink reduced by an estimated 25-34%. These findings suggest that, in a UK university café context, default nudges can encourage plant-based milk consumption and reduce dairy intake. This provides implications for adopting sustainable default nudges in the university and wider food sector to help reduce the environmental impacts of animal agriculture.