Red and processed meat consumption and mortality: dose–response meta-analysis of prospective cohort studies

OBJECTIVE: To examine and quantify the potential dose-response relationship between red and processed meat consumption and risk of all-cause, cardiovascular and cancer mortality. DESIGN: We searched MEDLINE, Embase, ISI Web of Knowledge, CINHAL, Scopus, the Cochrane library and reference lists of retrieved articles up to 30 November 2014 without language restrictions. We retrieved prospective cohort studies that reported risk estimates for all-cause, cardiovascular and cancer mortality by red and/or processed meat intake levels. The dose-response relationships were estimated using data from red and processed meat intake categories in each study. Random-effects models were used to calculate pooled relative risks and 95 % confidence intervals and to incorporate between-study variations. RESULTS: Nine articles with seventeen prospective cohorts were eligible in this meta-analysis, including a total of 150 328 deaths. There was evidence of a non-linear association between processed meat consumption and risk of all-cause and cardiovascular mortality, but not for cancer mortality. For processed meat, the pooled relative risk with an increase of one serving per day was 1·15 (95 % CI 1·11, 1·19) for all-cause mortality (five studies; P<0·001 for linear trend), 1·15 (95 % CI 1·07, 1·24) for cardiovascular mortality (six studies; P<0·001) and 1·08 (95 % CI 1·06, 1·11) for cancer mortality (five studies; P<0·001). Similar associations were found with total meat intake. The association between unprocessed red meat consumption and mortality risk was found in the US populations, but not in European or Asian populations. CONCLUSIONS: The present meta-analysis indicates that higher consumption of total red meat and processed meat is associated with an increased risk of total, cardiovascular and cancer mortality.