Associations of the consumption of unprocessed red meat and processed meat with the incidence of cardiovascular disease and mortality, and the dose-response relationship: A systematic review and meta-analysis of cohort studies.

Objectives: The aim of this study was to examine the associations of unprocessed red meat and processed meat consumption with cardiovascular disease (CVD) incidence and mortality, and the dose-response relationship.

Methods: Published literature was retrieved through a structured search of 10 electronic databases: MEDLINE/PubMed, Scopus, SciELO, LILACS, ScienceDirect, Web of Science, Cochrane (CENTRAL), WHOLIS, PAHO and Embase, without language or year of publication restrictions. In addition, we searched the references of published studies. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes: The PRISMA Statement.

Results: Twenty-one prospective cohort studies were included in the systematic review. The CVDs evaluated in the inserted studies were stroke, heart failure (HF) and coronary heart disease (CHD). Considering the heterogeneity found in the studies, for the meta-analysis, 9 articles were included. The results presented in the meta-analysis of the association of consumption of unprocessed red meat and CVD indicated that there was a significant association with total stroke incidence (RR 1.10; 95%; CI 1.01 to 1.19; p = 0.02). There was no association with Ischemic stroke incidence, nor CHD Mortality with consumption of unprocessed red meat. However, for Hemorrhagic Stroke Mortality the assessment in the consumption of unprocessed red meat showed an association of protection for women (RR 0.64; 95%; CI 0.45 to 0.91; p = 0.01). As for the results of the meta-analysis of the association between consumption of processed meat and CVD, they indicated that there was a significant association with total stroke incidence (RR 1.17; 95%; CI 1.08 to 1.26; p < 0.0001). There was no association with Ischemic stroke, nor with CHD Mortality with consumption of processed meat. Some studies that showed no association of risk, presented a significant linear trend dose response for the association of the consumption of unprocessed red meat (Bernstein et al. 2010; Nagao et al. 2012) or processed meat (Bernstein et al. 2012) and CVD.

Conclusion: According to the results found in the meta-analysis, the consumption of unprocessed red meat and processed meat are associated with the incidence of stroke, however, no positive association was observed in relation to mortality from CVD. This systematic review and meta-analysis protocol was registered on the PROSPERO (number: CRD42019100914).