Systematically testing the effects of promotion techniques on children’s fruit and vegetables intake on the long term: a protocol study of a multicenter randomized controlled trial

BACKGROUND: Eating a diet rich in fruit and vegetables is essential for healthy development, protects against chronicle diseases, and increases mental well-being. Numerous studies have consistently shown that children do not consume enough fruit and vegetables, especially among children from low socioeconomic status, while foods high in fat, sugar and salt are over-consumed. In order to improve children’s eating behavior, there is an urgent need to systematically test novel and effective methods to make fruit and vegetables more appealing and increase the intake among children. Therefore, the main aim of the proposed project is to test if food promotion techniques increase children’s fruit and vegetable intake, both on the short- and long-term. METHODS: Three studies will be conducted. First, to develop the vlogs in co-creation, multiple focus groups will be held with (1) children (N = 25, between 8 and 13 years), (2) parents (N = 10), (3) vloggers (N = 5), and (4) fruit and vegetable producers and marketers (N = 5). Second, a multicenter randomized clinical trial will be conducted among 10 primary schools. A mixed repeated measure design with three different conditions will be used: (1) control, (2) a vlog unboxing fruit and vegetables (preparing and tasting), and (3) a vlog doing a challenge with the fruit and vegetables (e.g., contests, tricks, games). Children between 7 and 13 will participate in the experiments (N = 350). Third, after 6 and 12 months follow-up measurements will take place. DISCUSSION: HFSS foods have higher intrinsically rewarding properties that make them more “wanted” and “liked” than fruit and vegetables, thereby inducing unhealthy eating behavior among children. Additionally, promotion for HFSS foods is omnipresent and increases the rewarding value of these foods. Moreover, some studies showed that the promotion of fruit and vegetables affects the intake, although a recent systematic review shows that evidence is inconclusive and a theoretical understanding for the underlying mechanism is missing. The current study aims to improve the existing knowledge by experimentally testing a newly developed theoretical model. TRIAL REGISTRATION: Netherlands Trial registration: NL8077, received on 12 October 2019.