Randomized controlled trial of a Messaging Intervention to increase fruit and vegetable intake in adolescents: Affective versus instrumental messages

Objective: The present research aimed to test the efficacy of affective and instrumental text messages compared to a no message control as a strategy to increase fruit and vegetable intake (FVI) in adolescents. Design. A randomized controlled trial was used test impact of different text messages compared to no message on FVI over a 2 week period. Method: A total of 1065 adolescents (14–19 years) from a high school of the South of Italy completed the baseline questionnaire and were randomly allocated to one of three conditions: instrumental messages (N = 238); affective messages (N = 300); no messages (N = 521). Students in the message conditions received one message each day over a 2 week period. The messages targeted affective (affective benefits) or instrumental (instrumental benefits) information about FVI. Self-reported FVI at two weeks was the key dependent variable. Analyses were based on the N = 634 who completed all aspects of the study. Results: Findings showed that messages significantly increased FVI, particularly in the affective condition and this effect was partially mediated by changes in affective attitude and intentions towards FVI. Conclusion: Text messages can be used to increase FVI in adolescents. Text messages based on affective benefits are more effective than text messages based on instrumental benefits.