“Miffy eats the rainbow!” – A colorful modeling- and reward-based intervention to increase willingness to taste fruit and vegetables in 3–7-year-old children

Diets rich in fruit and vegetables (F&Vs) improve cognitive functioning and reduce the risk of non-communicable diseases in children. Nevertheless, 59% of Dutch children do not meet recommended intake levels. Given the importance of color in children's food choices, the concept of "eat the rainbow" presents a promising approach. This project aimed to evaluate the effects of a modeling- and reward-based intervention to stimulate the consumption of colorful foods to increase willingness to taste different F&Vs among children aged 3-7 years. 164 children from Dutch elementary schools participated in a nested cluster randomized multi-arm parallel design study. During two morning school breaks, children were invited to choose from ten F&Vs in five different colors. Their willingness to taste and ad libitum intake were recorded. The first session served as a baseline with no intervention, while the second session involved either the Miffy intervention (modeling- and reward-based), a reward-only intervention (reward-based), or a control session. In the Miffy intervention, children listened to a story about Miffy eating the rainbow before tasting F&Vs and they received colored stickers (e.g., red sticker for tomatoes, green sticker for celery) upon tasting them. In the reward-only intervention, children received a sticker upon tasting a food. The Miffy group showed a higher probability (P(tasted) = 0.39) of tasting a food product compared to the control group (P(tasted) = 0.29; OR = 0.63, p = .04). No significant differences were observed between the Miffy and reward-only groups or between the reward-only and control groups. Both interventions did not significantly impact intake or liking of the foods. The Miffy-themed intervention demonstrates potential to enhance children's willingness to taste F&Vs, primarily due to the use of non-food incentives.