Relevant studies were identified by systematically searching Medline, EMBASE and ISI Web of Knowledge. Reported hazard ratios (HRs) for 25(OH)D categories were recalculated employing comprehensive trend estimation from summarized dose-response data and pooled in a random effects model meta-analysis.
Overall, 12 original studies were included in the review and meta-analysis comprising 32,142 mainly elderly study participants with measured 25(OH)D of whom 6921 died during follow-up. An inverse association between 25(OH)D levels and all-cause mortality was found in all but two studies that was statistically significant in several of the individual studies. In meta-analysis, 25(OH)D levels were significantly inversely associated with all-cause mortality with a pooled HR of 0.92 (95 % confidence interval: 0.89-0.95) for a 20 nmol/l increase in 25(OH)D levels.
In this meta-analysis of prospective, population-based cohort studies, a 20 nmol/l increase in 25(OH)D levels was associated with an 8 % lower mortality in the general elderly population. This agrees with results from meta-analyses on randomized controlled trials that found a decrease in mortality with vitamin D3 supplementation of a comparable magnitude.