Role of multivitamins and mineral supplements in preventing infections in elderly people: systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE To evaluate the effectiveness of multivitamins and mineral supplements in reducing infections in an elderly population. DESIGN Systematic review and meta-analysis of randomised controlled trials. DATA SOURCES Medline and other databases. Reference lists of identified articles were inspected for further relevant articles. SELECTION OF STUDIES Trials were included if they evaluated the effect of multivitamins and mineral supplements on infections in an elderly population. REVIEW METHODS Studies were assessed for the methodological quality by using the Jadad instrument. If the data required for the analyses were not available from the published articles we requested them from the original study authors. Meta-analysis was undertaken on three outcomes: the mean difference in number of days spent with infection, the odds ratio of at least one infection in the study period, and the incidence rate ratio for the difference in infection rates. Data on adverse events were also extracted. RESULTS Eight trials met our inclusion criteria. Owing to inconsistency in the outcomes reported, only a proportion of the trials could be included in each meta-analysis. Multivitamins and mineral supplements were found to reduce the mean annual number of days spent with infection (three studies) by 17.5 (95% confidence interval 11 to 24, P < 0.001). The odds ratio for at least one infection in the study period (three studies) was 1.10 (0.81 to 1.50, P = 0.53). The infection rate ratio (four studies) was 0.89 (0.78 to 1.03, P = 0.11). Reporting of adverse events was poor. CONCLUSION The evidence for routine use of multivitamin and mineral supplements to reduce infections in elderly people is weak and conflicting. Study results are heterogeneous, and this is partially confounded by outcome measure.