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

Abstract

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.

Keywords: Aging; Cognition; Cognitive decline; Cognitive function; Older people; Vitamin D.

Fig. 1

Flowchart of the study population. CDT, Clock Drawing test; DST-b, Digit Span test backward; DST-f, Digit Span test forward; MMSE, Mini-Mental State Examination; TMT-A, Trail Making test part A; TMT-B, Trail Making test part B; VFT-a, verbal fluency tasks semantical; VFT-p, verbal fluency tasks phonological. Asterisk (*) symbols indicate daily energy intakes for men < 800 kcal or > 4000 kcal and women < 500 kcal or > 3500 kcal

Fig. 2

Interaction between energy-adjusted cumulative average dietary vitamin D intake and different baseline variables of the study potentially related to cognitive function. Abbreviations: BMI, body mass index; CI, confidence interval. Multivariable-adjusted models were adjusted for the respective cognitive test score at baseline, age (years), sex, intervention PREDIMED-Plus randomized groups, and participating center (south/north), education level (primary, secondary, or college), civil status (single, divorced or separated, married, widower), body mass index (kg/m²), physical activity (METs/min/day), smoking status (current, former, or never), energy-adjusted cumulative average alcohol consumption in g/day (and adding the quadratic term), depressive symptomatology (yes/no), diabetes prevalence (yes/no), hypertension prevalence (yes/no), hypercholesterolemia prevalence (yes/no), and energy-adjusted cumulative average consumption of food groups (vegetables, fruits, legumes, cereals, oils and fats, olive oils, biscuits, meat, fish, dairy, nuts [g/day], coffee and tea [mL/day]). Significant values (P < 0.05) were highlighted in bold type

Fig. 3

Sensitivity analyses for the longitudinal association between energy-adjusted cumulative average dietary vitamin D intake and changes in cognitive function over a 2-year follow-up period in the PREDIMED-Plus cohort. Abbreviations: GCF, global cognitive function; MMSE, Mini-Mental State Examination. From the top to the bottom, removal of participants at baseline (1) with MMSE < 24, (2) with extreme percentiles of GCF z-score (< 2.5%, > 97.5%). Basic models were adjusted for the respective cognitive test score at baseline, age (years), and sex. Multivariable-adjusted models were adjusted for the respective cognitive test score at baseline, age (years), sex, intervention PREDIMED-Plus randomized groups, and participating center (south/north), education level (primary, secondary, or college), civil status (single, divorced or separated, married, widower), body mass index (kg/m²), physical activity (METs/min/day), smoking status (current, former, or never), energy-adjusted cumulative average alcohol consumption in g/day (and adding the quadratic term), depressive symptomatology (yes/no), diabetes prevalence (yes/no), hypertension prevalence (yes/no), hypercholesterolemia prevalence (yes/no), and energy-adjusted cumulative average consumption of food groups (vegetables, fruits, legumes, cereals, oils and fats, olive oils, biscuits, meat, fish, dairy, nuts [g/day], coffee, and tea [mL/day]). Significant values (P < 0.05) were highlighted in bold type