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

Abstract

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.

Fig 1

Results of literature search and selection of randomised controlled trials for the meta-analyses. Values are numbers of trials (QUOROM statement flow diagram)

Fig 2

Random effects meta-analysis of outcome: mean difference in number of days of infection between multivitamin+supplement and placebo groups in 12 months

Fig 3

Fixed effect meta-analysis of outcome: odds ratio for at least one infection during the study period between multivitamin+supplement and placebo groups

Fig 4

Fixed effect meta-analysis of outcome: incidence rate ratio for infection between multivitamin+supplement and placebo groups