A nudging intervention study targeting vegetable intake in a university cafeteria in Japan

Abstract

Nudging interventions are behavioral economic strategies that aim to influence decision-making by (re)designing the environment. Numerous studies have explored the use of nudging to promote healthier food choices; however, most have been conducted in Europe or North America. This study implemented nudging interventions aimed at increasing vegetable consumption, focusing on fukusai (Japanese side dishes), in a university cafeteria in Japan. Two distinct nudging strategies were implemented using paper tray sheets with different designs over a 5-week period. The week-2 tray sheet guided food placement according to traditional Japanese dining etiquette, emphasizing the designated area for side dishes. The week-4 tray sheet provided information on inadequate vegetable intake among young adults and recommended specific vegetable side dishes. The week-2 intervention led to a slight increase in side-dish sales, although the effect was not statistically significant. Unexpectedly, the week-4 intervention resulted in a significant decline in side-dish sales. Several factors may have contributed to the interventions' limited effectiveness, including the short duration of each intervention phase, the already-high baseline consumption of side dishes, and possible resistance to the persuasive messaging used in week 4. These findings highlight the importance of avoiding directive or persuasive messaging, which may have unintended negative effects. Our results contribute to the growing literature on cafeteria-based interventions among various countries and cross-cultural differences.