Dietary vitamin D intake and 2-year changes in cognitive function in older adults with overweight or obesity and...

The protective role of dietary vitamin D intake on cognitive function is of interest, but evidence remains inconsistent. We aimed to evaluate the association between dietary vitamin D intake and 2-year cognitive changes in older adults at risk of cognitive decline. This longitudinal study comprised 5454 individuals (aged 55-75 years in men and 60-75 years in women) who exhibited overweight/obesity and metabolic syndrome. Data on dietary vitamin D intake was assessed using a validated 143-item food frequency questionnaire. Cognitive function was assessed through five composite scores derived from a comprehensive battery of eight neuropsychological tests, encompassing global cognitive function, general cognitive function, attention, executive function, and language domains. Multivariable-adjusted linear regression models were fitted to examine the association between energy-adjusted cumulative average dietary vitamin D intake over time and 2-year changes in cognitive function. After adjusting for multiple covariates, energy-adjusted cumulative average dietary vitamin D intake as a continuous variable was associated with greater 2-year improvements in global cognitive function (β 1.18 × 10^-2; 95% CI 0.19 × 10^-2 to 2.17 × 10^-2), executive function (β 1.12 × 10^-2; 95% CI 0.03 × 10^-2 to 2.21 × 10^-2), and language (β 1.61 × 10^-2; 95% CI 0.43 × 10^-2 to 2.78 × 10^-2). Additionally, the higher cumulative average dietary vitamin D intake quartile was associated with an increase in global cognitive function (β 7.10 × 10^-2; 95% CI 0.59 × 10^-2 to 13.6 × 10^-2), language (β 7.07 × 10^-2; 95% CI - 0.52 × 10^-2 to 14.7 × 10^-2), and a lower decline in attention (β 9.58 × 10^-2; 95% CI 1.60 × 10^-2 to 17.5 × 10^-2). A higher dietary vitamin D intake was associated with modest favorable changes in cognitive function and a reduced cognitive decline over a 2-year period. These findings highlight the need for further research to explore the potential benefits of boosting dietary vitamin D intake for cognitive health in older adults.