Effects of using multivitamins as dietary supplements on cognitive function in older adults: a systematic review and meta-analysis

Multivitamins were widely used health supplements that replenished essential nutrients in the human body. Despite their popularity, the impact of multivitamins on the cognitive function of older adults remained unclear and contentious. This study offered a comprehensive review and meta-analysis of research published until June 2024, analyzing the effects of multivitamins on various cognitive functions in individuals aged 65 and older. We included ten randomized controlled trials encompassing 13600 participants from multiple databases. These studies evaluated the impact of multivitamins on reasoning, memory, learning, visual perception, idea production, cognitive speed, psychomotor abilities, and higher cognitive functions. Our meta-analysis revealed that multivitamins significantly enhanced delayed free recall (standardized mean difference (SMD) = 0.09, 95% confidence interval (CI) : [0.05, 0.13], P < 0.0001). However, they had no substantial effects on immediate free recall (SMD = 0.85, 95% CI: [−0.18, 1.90], P = 0.11), idea production (SMD = 0.00, 95% CI: [−0.04, 0.03], P = 0.86), or cognitive speed (SMD = 0.34, 95% CI: [−0.07, 0.74], P = 0.11). Thus, while multivitamins facilitated delayed free recall, they did not significantly improve other cognitive functions in older adults.