Li S, Guo Y, Men J, et al. - Whether supplementation with vitamin B can prevent cognitive decline of elderly adults, was inquired via this systematic review and meta-analysis. PubMed, Embase, The Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Scopus, Science Direct, PsycINFO, all were explored to identify randomized controlled trials (RCTs) assessing the efficacy of vitamin B in mild cognitive impairment (MCI) patients or elderly adults without cognitive impairment. This meta-analysis included 21 RCTs consisting of 7571 participants. Findings indicate the likely efficacy of vitamin B supplements in delaying or maintaining the cognitive decline of elderly adults. It can be advised that consideration should be given to vitamin B supplements as a prophylactic medication to MCI patients or elderly adults without cognitive impairment.