Dairy products intake and its association with cognitive function in older adults: A systematic review and...

Emerging evidence suggests a possible association between dairy product intake and cognitive function in older adults; however, previous findings remain inconsistent. This study aimed to systematically evaluate the association between dairy intake and cognitive outcomes in older adults, and explore potential dose-response relationships and regional differences.

We searched PubMed, MEDLINE, Embase, Cochrane Library, Scopus, and CINAHL from their inception to 31 December 2024. Dose-response analysis was performed for cohort studies to assess the impact of different types and quantities of dairy intake on cognitive subdomains. Meta-regression was used to explore sources of heterogeneity. The results were presented as relative risks (RRs), odds ratios (ORs), and mean differences (MDs) with 95 % confidence intervals (CIs). The methodology followed the PRISMA guidelines for systematic reviews and meta-analyses.

A total of 38 studies were included, comprising 21 cohort studies, 15 cross-sectional studies, and 2 randomized controlled trials. We stratified dairy products intake levels, and higher total dairy intake was associated with a reduced risk of cognitive decline and improved global cognitive function (Cohort: medium vs low, RR: 0.92, 95 % CI: 0.85, 0.99; high vs low, RR: 0.85, 95 % CI: 0.73, 0.98; Cross-sectional: high vs low, OR: 0.64, 95 % CI: 0.49, 0.82). Fermented dairy products were associated with improved verbal memory and executive function, whereas higher milk intake showed a potential association with poorer verbal memory in certain instances (medium vs low, MD: -0.04; 95 % CI: -0.09, 0.01; high vs low, MD: -0.05; 95 % CI: -0.09, -0.01). Evidence showed nonlinear associations, with the lowest risk of cognitive decline associated with a daily intake of 150 g of dairy products (p-nonlinear = 0.009, RR: 0.86, 95 % CI: 0.78, 0.95), and 30 g/day of whole-fat dairy (p-nonlinear = 0.007, RR: 0.83, 95 % CI: 0.74, 0.94). Regional differences were observed, with cognitive outcomes varying between European and Asian populations, possibly reflecting dietary habits and cultural contexts.

Dairy intake, especially fermented products and moderate total intake, may support cognitive health in older adults, though associations vary by region and dairy type. More high-quality studies are needed to clarify these relationships and guide dietary recommendations.