Oral health and depressive symptoms among older adults in urban China: a moderated mediation model analysis

BACKGROUND: This study explored the association between oral health and depression occurs via daily dietary satisfaction as a mediator, and that body mass index could moderate the path between daily dietary satisfaction and depression. METHODS: Data for this research were derived from a community survey adopting quota sampling in the cities of Tianjin and Shijiazhuang in mainland China in 2020 (N = 781). The moderated mediation model was tested by using bootstrapping with resampling strategies, and the Johnson-Neyman technique was used to visualize the moderating effect of body mass index. RESULTS: A significant negative association between oral health and depression has been indicated (B = −0.22, SE = 0.11, 95%CI [− 0.44, − 0.01]), and dietary satisfaction partially mediated the relationship between oral health and depression (B = −0.04, SE = 0.02, 95%CI [− 0.09, − 0.002]). The path was moderated by body mass index, and the effect of dietary satisfaction on depression was much greater in people with relatively low body mass index. CONCLUSIONS: This study present evidence for policymakers and researchers that strategies to enhance oral health and daily dietary satisfaction could be important for preventing depression in Chinese older adults, and especially for the relatively fitter older groups with lower body mass index. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-022-03542-1.