Nudging healthier food choices among low socioeconomic position consumers: a field study in an Italian social supermarket

Promoting healthier food choices among low socioeconomic position (low-SEP) consumers is a public health priority, but real-world evidence on the effectiveness of nudging interventions in this population remains limited. Social supermarkets, where surplus food is allocated to low-SEP households without monetary exchange, offer a rare opportunity to examine how interventions affect food selection independent of price. This study examined whether nudging interventions could increase whole-grain pasta selection at an Italian social supermarket in Parma over 61 operating weeks, a setting and duration rarely examined in the nudging literature. The study used a sequential design comprising five periods: control phase, behavioral intervention (increased product availability), combined intervention (availability plus an evaluative label and an infographic), return to the behavioral intervention only, and follow-up. The weekly proportion of whole-grain pasta sales was calculated from aggregate point-of-sale (POS) data and analyzed using one-way ANOVA with Games-Howell post-hoc comparisons. Whole-grain pasta selection increased overall, from 1.67% during the control period to 16.63% during the follow-up (F(4, 56) = 11.95, p < 0.001, η2 = 0.460). The combined intervention, the second behavioral phase, and the follow-up all differed significantly from the control. The elevated selection observed during the interventions persisted throughout the follow-up. In this single-site field study, combining availability-based nudges with simple cognitive elements was associated with a meaningful and sustained increase in whole-grain pasta selection among low-SEP consumers. Although the sequential design cannot fully separate the interventions from contextual and seasonal influences, these findings support further evaluation of nudging strategies in food assistance programs.