Mediating effects of physical activities and cognitive function on the relationship between dietary diversity and all-cause mortality in community-dwelling older adults.

Background: Although dietary diversity (DD) has been confirmed to be associated with multiple health outcomes and longevity in older people, the related mechanisms have not been elucidated. In this study, we explored the mediating roles of physical activities and cognitive function in the relationship between DD and all-cause mortality.

Methods: We recruited 34 068 community-dwelling older adults aged ≥60 years from the Chinese Longitudinal Healthy Longevity Study and followed them up until 2018. Dietary diversity score (DDS) was assessed by the intake frequency of nine food sources. We evaluated physical activities and cognitive function using the Katz index and Mini-Mental State Examination. We explored the mediating roles of physical activities and cognitive function between DDS and all-cause mortality using mediated analyses in Cox proportional risk regression models.

Results: A total of 25 362 deaths were recorded during 148 188.03 person-years of follow-up. Participants with physical disability and cognitive impairment had lower DDS than the normal group (P < 0.001). After controlling for all covariates, DDS, physical activities, and cognitive functioning were negatively associated with all-cause mortality. Physical activities and cognitive function mediated 18.29% (95% confidence interval (CI) = 12.90-23.10) and 27.84% (95% CI = 17.52-37.56) of the total effect of DDS on mortality, respectively.

Conclusions: Physical activities and cognitive function mediated the association between DDS and all-cause mortality. Maintaining DD may benefit early death prevention by reducing physical disability and cognitive impairment in community-dwelling older people.