Red meat and heart disease: what do controlled trials tell us?

Red meat consumption has become quite a contentious issue in the past few decades. The prevailing view in the public health community is that red meat is unhealthy, but this conclusion is based heavily on contradictory observational evidence. For example, several studies have found a relationship between red meat consumption and cardiovascular disease morbidity^[1] and mortality^[2], while others^[3] have not^[4] and argue that these associations were owed to problems with data collection and how red meat is classified (such as grouping unprocessed and and processed red meats together).

Regardless, observational evidence does not allow for establishing causality. At the same time, performing randomized controlled trials that evaluate long-term health outcomes such as dying from a heart attack are difficult and expensive to conduct. Accordingly, researchers instead look at known cardiovascular disease risk factors, such as a person’s blood lipids or blood pressure, which change on a relatively short timescale. If red meat does increase the risk of cardiovascular disease, then there is a good chance that it does so through these well-established cardiovascular disease risk factors.

A previous meta-analysis^[5] of eight studies suggested that beef consumption did not significantly alter the blood lipid profile of healthy adults when compared with poultry or fish. However, this doesn’t tell us the effect of adding red meat into the diet per se, and does not include all types of red meat, only beef. The study under review is a meta-analysis of randomized controlled trials investigating the impact of red meat consumption on blood lipids and blood pressure, two well-established cardiovascular disease risk factors.

Observational evidence reports an inconsistent link between red meat consumption and cardiovascular disease. However, no study has yet to systematically review controlled trials looking at red meat and cardiovascular disease risk factors. The study under review is a meta-analysis of randomized controlled trials investigating the impact of red meat consumption on blood lipids and blood pressure.