Mediating role of fruit and vegetable intake and social interaction between oral function and mental health in older adults aged ≥75 years: The SONIC study.

Purpose: This study aimed to explore the association between oral function and mental health status in older adults and to determine the potential mediating roles of fruit and vegetable intake and social interaction.

Methods: This cross-sectional study included 478 community-dwelling older adults aged ≥75 years in Japan. Oral functions (occlusal force, masticatory performance, tongue pressure, tongue-lip motor function, and swallowing function), mental health status, dietary assessment, frequency of outings and interactions with others, and the following confounders were evaluated: educational level, financial satisfaction, residential status, comorbidities, and cognitive function. Structural equation modeling was used to assess the following: (a) a basic model, which hypothesized that oral function has a direct effect on mental health status, and (b) a mediation model, which hypothesized that fruit and vegetable intake and social interaction have potential mediating effects on the association between oral function and mental health status.

Results: The basic model revealed a positive direct association between oral function and mental health status (standardized coefficient = 0.10, P = 0.04). Fruit and vegetable intake and social interactions were identified as mediators; however, no direct association with oral function was observed in the mediation model (P = 0.28), indicating that oral function was indirectly associated with mental health status through the mediating effects of fruit and vegetable intake and social interactions.

Conclusions: Oral function showed a significant association with mental health status in community-dwelling older adults. Fruit and vegetable intake along with social interactions mediate this relationship.