Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life

Efficacy of Vitamins on Cognitive Function of Non-Demented People: A Systematic Review and Meta-Analysis

“…As secondary outcomes of this study, we employed the mean difference between baseline and follow-up assessments of validated cognitive test scores on episodic memory, executive function, processing speed, attention, and visuospatial function. If a study evaluated a specific cognitive function using two or more cognitive tests simultaneously, we included the more frequently employed test for a particular cognitive domain among other studies [6]. When two or more cognitive tests were equally employed among the included studies, we chose one test that was more representative of the particular cognitive domain.…”

“…During the same period, we also searched for grey literature through the Open Grey database and the World Health Organization portal which covers ClinicalTrials.gov. A search strategy was developed for each of the databases based on previous literature [6], and detailed search keywords are provided in the Supplementary Materials (Table S1).…”

“…However, the effects of vitamins on cognitive function of non-demented elderly have been inconsistent even in meta-analyses on randomized or quasi-randomized, placebo-controlled trials [6][7][8][9][10][11][12][13][14]. These conflicting results may be attributable to several limitations of previous meta-analyses.…”

“…These conflicting results may be attributable to several limitations of previous meta-analyses. Firstly, the proportion of the subjects with mild cognitive impairment (MCI) was not uniform across the studies, and the effect of vitamins on cognitive function may be different between subjects with normal cognition and those with MCI [6][7][8][9][10][11][12][13][14]. Secondly, the effect of different geographical locations or ethnicities was not considered in all previous meta-analyses, even though they are related to dietary habits and genetic backgrounds.…”

“…Secondly, the effect of different geographical locations or ethnicities was not considered in all previous meta-analyses, even though they are related to dietary habits and genetic backgrounds. Thirdly, most previous meta-analyses did not examine the isolated effects of vitamins by allowing the inclusion of minerals or other cofactors as intervention material [6][7][8]12,14].…”