Red meat and processed meat consumption and all-cause mortality: a meta-analysis.

High consumption of red meat and processed meat has been associated with increased risk of several chronic diseases. We conducted a meta-analysis to summarize the evidence from prospective studies on red meat and processed meat consumption in relationship to all-cause mortality. Pertinent studies were identified by searching PubMed through May 2013 and by reviewing the reference lists of retrieved articles. Prospective studies that reported relative risks with 95% confidence intervals for the association of red meat or processed meat consumption with all-cause mortality were eligible. Study-specific results were combined by using a random-effects model. Nine prospective studies were included in the meta-analysis. The summary relative risks of all-cause mortality for the highest versus the lowest category of consumption were 1.10 (95% confidence interval (CI): 0.98, 1.22; n = 6 studies) for unprocessed red meat, 1.23 (95% CI: 1.17, 1.28; n = 6 studies) for processed meat, and 1.29 (95% CI: 1.24, 1.35; n = 5 studies) for total red meat. In a dose-response meta-analysis, consumption of processed meat and total red meat, but not unprocessed red meat, was statistically significantly positively associated with all-cause mortality in a nonlinear fashion. These results indicate that high consumption of red meat, especially processed meat, may increase all-cause mortality.