The Relationship Between Dietary Diversity and Mental Health Among Chinese Older Adults: Evidence from the Chinese Longitudinal Healthy Longevity Survey

Background: Previous research has confirmed that dietary diversity is positively linked to mental health outcomes in older populations. Nevertheless, relevant evidence focusing specifically on Chinese older adults remains limited, and the internal mechanisms underlying this association I confirm. are not fully understood. Against this background, this study intended to investigate the association between dietary diversity and mental health among Chinese older individuals, explore the chain mediating roles of sleep quality and self-perceived quality of life, and further test whether gender moderates the above direct and mediating pathways. Methods: Using 2018 CLHLS data, 10,089 older adults aged 60 and above were selected as valid samples. Pearson correlation analysis was employed to determine the relationships between key variables. Hayes' PROCESS macro Model 6 was used for baseline serial mediation analysis, and Model 85 was used for moderated serial mediation with gender as the moderator, adopting 5000 bootstrap samples. Results: The results revealed significant positive correlations (p < 0.01) between key variables, including dietary diversity, sleep quality, self-rated quality of life, and mental health. Model 6 showed that dietary diversity serves as a positive and significant predictor of mental health (B = 0.130, p < 0.001). Three significant mediating pathways were identified through which dietary diversity affects mental health: (1) sleep quality (B = 0.076, 95% CI: 0.062, 0.092), (2) self-rated quality of life (B = 0.100, 95% CI: 0.083, 0.118), and (3) sleep quality and self-rated quality of life (B = 0.020, 95% CI: 0.016, 0.025). The total mediating effect of the three pathways reached 59.94%. Model 85 found that the interaction term of dietary diversity x gender was non-significant (p > 0.05), demonstrating no statistically significant gender moderation of any pathway. Gender-stratified conditional effects revealed numerical differences across subgroups. Conclusions: Higher dietary diversity is significantly correlated with better mental health among Chinese older adults. Sleep quality and self-rated quality of life play significant roles as serial mediators in this association. Although gender does not statistically moderate the whole association mechanism, subtle gender heterogeneity exists in the pathway effect magnitude. The above findings offer novel insights into the underlying mechanisms. Strategies aimed at improving dietary diversity, combined with targeted interventions to enhance sleep quality and self-rated quality of life, with slight gender-differentiated auxiliary suggestions, may effectively promote mental health and contribute to active aging in later life.