Effects of ‘SPRAT’ programme for dietary and lifestyle education to improve psychosomatic symptoms and dietary habits among adolescents: a cluster randomised controlled trial

BACKGROUND: Dietary and lifestyle modifications to reduce subjective psychosomatic symptoms (SPS) have become an important topic worldwide. We developed a school-based dietary and lifestyle education programme that involved parents/guardians in reducing SPS in adolescents (SPRAT). The programme encouraged parents/guardians to participate in adolescents’ healthy dietary and lifestyle modifications to reduce SPS, increase enjoyment of school life, and foster appropriate dietary intake. This study evaluated the effectiveness of SPRAT in reducing SPS and in altering dietary behaviour among adolescents. METHODS: A 6-month cluster randomised controlled trial using SPRAT and the usual school programme (control) was performed. Participants were middle school students in Japan who provided informed consent. Outcomes were SPS scores assessed at baseline and 2, 4, and 6 months after baseline and the proportions of dietary and lifestyle factors achieved such as enjoyment of school life and dietary intakes assessed by FFQW82. Change from baseline (CFB) at 6 months was the primary endpoint. A linear mixed-effects model was applied. As for dietary intake, the treatment effect was estimated as an interaction term between baseline and treatment “baseline*treatment”. RESULTS: The intention-to treat analysis included 951 (94.7%) and 1035 (89.8%) individuals in the SPRAT and control groups, respectively. The CFB in the 6-month SPS score adjusted for baseline was lower in the SPRAT group (-0.29) than in the control group (0.62), but the difference was not statistically significant -0.91 (p = 0.093). CONCLUSIONS: Although the primary endpoint tended to denote improvement in the SPRAT group compared to the control group, the improvement was not significant. Favourable effects were observed in some secondary outcomes and statistically significant treatment*baseline interactions were observed for several dietary intakes. These results imply that CFBs of dietary intake were increased or decreased in a favourable direction depending on the baseline intake, especially in the SPRAT group. TRIAL REGISTRATION: UMIN000026715. (27/03/2017) SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-022-12832-7.