Interaction effects of co-consumption of fast food and sugar-sweetened beverages on psychological symptoms: Evidence from a nationwide survey among Chinese adolescents

Background: Although fast food and sugar-sweetened beverages (SSBs) consumption have been closely linked to childhood and adolescent obesity, the data regarding their co-consumption and relationship to mental health remains controversial. Methods: A multi-centered population-based survey was conducted among Chinese adolescents from grades 7 to 12. Data about participants' consumption of fast foods and SSBs were obtained from self-reported questionnaires. Psychological symptoms were assessed using the Multi-dimensional Sub-health Questionnaire of Adolescents (MSQA). The association between co-consumption of fast food and SSBs and psychological symptoms was assessed using quantile regression analysis, adjusting for covariates. Results: Approximately one-fifth of the 14,500 participants reported psychological symptoms. The regression coefficient (β) value increased as the quantile of fast food, SSBs, and co-consumption increased in the quantile regression model, and the model had an excellent goodness-of-fit (F = 192.51, p < 0.001). In the interaction model, fast food and SSBs in combination were associated with greater odds of psychological symptoms (aOR = 1.90, 95% CI: 1.69, 2.12). The synergy index, relative excess risk of interaction, and attributable proportions were 1.86 (95% CI: 1.17, 2.96), 0.4 (95% CI: 0.20, 0.63), and 0.22 (95% CI: 0.11, 0.33), respectively. Limitations: Information bias is inevitable in self-reported data among participants. The ability to assess causal relationships is reduced by a cross-sectional study design. Conclusions: Our findings suggest that co-consumption of fast food and SSBs was cross-sectionally associated with mental health problems among adolescents.