The effect of nudging strategies on reducing diners' salt intake: Evidence from a randomized field experiment

Using a field experiment conducted in a real table-service restaurant, this study investigated how nudging strategies can be used to guide diners to choose healthier food with lower sodium in an urban area of China. By randomly employing a changing default nudging strategy and a verbal prompting nudging strategy in the same setting and with 313 tables of diners, this study compared both changes in salt-reducing ordering behavior and salt intake reduction in two nudging groups and a control group. The results showed that both nudging strategies have significantly promoted diners to make salt-reducing ordering behavioral changes. The verbal prompting nudging strategy was significantly more effective than the changing default nudging strategy in altering diners' ordering behavior; however, its efficacy was significantly moderated by table size and diners' taste primacy. The changing default nudging strategy proved robust against diner heterogeneity and achieved a significant reduction in per-person sodium intake, thus representing a more promising strategy for broader application. The findings of the present study provide empirical evidence for implementing precision nudging policies to reduce salt intake in restaurant settings. We suggest that health authorities prioritize the changing default nudging strategy for initial implementation in restaurants as a practical approach for improving public health.