Promoting vegetable acceptance in toddlers using a contingency management program: A cluster randomised trial.

Children learn to accept novel foods by repeated exposure to these foods. In the current study, we investigated in toddlers whether a contingency management program (The Vegetable Box), comprising repeated vegetable taste exposure with contingent non-food rewards, is particularly potent at increasing recognition of and willingness to try vegetables. A total of 598 children (1-4 years old) recruited at 26 different day-care centres in the Netherlands took part. The day-care centres were randomly assigned to one of three conditions ('exposure/reward', 'exposure/no reward', or 'no exposure/no reward'). At the start and directly after the 3-month intervention period, all children were asked to identify various vegetables (recognition test; max score = 14) and whether they would like to taste and consume 1 or 2 bite-size pieces of tomato, cucumber, carrot, bell pepper, radish, and cauliflower (willingness to try test). Data were analysed with linear mixed-effects regression analyses (for recognition and willingness to try separately) with condition and time as independent variables, and adjusting for day-care centre clustering. Vegetable recognition significantly increased in both the 'exposure/reward' and the 'exposure/no reward' group, relative to the 'no exposure/no reward' control group. The willingness to try vegetables only increased significantly in the 'exposure/reward' group. Offering vegetables to children at day-care centres significantly increased toddlers' ability to identify various vegetables, but rewards contingent upon tasting vegetables appear particularly effective to also increase children's willingness to try (i.e., taste and consume) different vegetables. This result corroborates and strengthens previous findings demonstrating the efficacy of similar reward-based programs.