Intervention Based Exclusively on Stage-Matched Printed Educational Materials Regarding Healthy Eating Does Not Result in Changes to Adolescents’ Dietary Behavior

Abstract

Purpose. To assess the impact of a six-month stage-based intervention on fruit and vegetable intake, regarding perceived benefits and barriers, and self-efficacy among adolescents. Design. Randomized treatment-control, pre-post design. Subjects/Setting. Schools were randomized between control and experimental groups. 860 adolescents from ten public schools in Brasília, Federal District, Brazil were evaluated at baseline; 771 (81%) completed the study. Intervention. Experimental group received monthly magazines and newsletters aimed at promotion of healthy eating. Measures. Self-reported fruit and vegetable intake, stages of change, self-efficacy and decisional balance scores were evaluated at baseline and post-intervention in both groups. Analysis. The effectiveness of the intervention was evaluated using the analysis of covariance model (ANCOVA) and repeated measurement analysis by means of weighted least squares. Comparison between the proportions of adolescents who advanced through the stages during the intervention was performed using the Mantel-Haenszel chi-square test. Results. After adjusting for sex and age, study variables showed no modifications through the proposed intervention. There was no statistical difference in participant mobility in the intervention and control groups between the stages of change, throughout the study. Conclusion. A nutritional intervention based exclusively on distribution of stage-matched printed educational materials was insufficient to change adolescents' dietary behavior.

Transtheoretical model-based nutritional interventions in adolescents: a systematic review

“…The final sample of 11 articles was published between 2003 and 2018 [16,17,18,19,20,21,22,23,24,25,26]. Two of the articles were assessed jointly because they covered the same intervention [19,20].…”

“…One study recruited adolescents from youth service agencies [19,20], another recruited adolescents in search of nutritional treatment [29] and a third recruited adolescents through digital media, radio and television [30]. The remaining studies recruited adolescents from schools [16,17,18,21,22,23,24,25,26]. The participants' age ranged from 7 to 19 years old, with only one study including preteens, whose age ranged from 7 to 12 years old [21].…”

“…The other studies included adolescents between twelve and nineteen years old. The majority of the studies targeted low-income populations [17,18,19,21,22,23,24,29], with three focusing on middle-income adolescents [16,25,26], one on African Americans [19] and two exclusively on girls [17,26]. Four studies focused on obese adolescents [21,26,29,30].…”

Protocol for a cluster randomised controlled trial on information technology-enabled nutrition intervention among urban adults in Chandigarh (India): SMART eating trial

“…Some trials have provided incentives to the participants in the form of provision of diets free of cost, while others made fruits and vegetables available at low cost in the study area [44,45]. In some trials, the control group did not receive any intervention which raises questions about study validity [41,46,47]. The majority of the identified interventions had no theoretical basis, and most of them used traditional methods of education such as individual/group counseling or printed material, and most did not achieve a significant change in dietary behaviour [40–45,48].…”

Cultural adaptation and psychometric properties of social cognitive scales related to adolescent dietary behaviors

“…The use of social cognitive measures related to dietary behaviors with good psychometric properties applied to interventions allows for the development and refinement of theory, as well to support the design and deliver interventions that are more effective. However, interventions conducted in developing countries [7][8][9][10] including Brazil that target dietary behaviors rarely assess the theoretical mechanisms of dietary behavior change. Such studies generally use food frequency questionnaires and dietary recalls to assess the dietary behavior change.…”