EAT FOR HEALTH.ORG

MYTH #4: FRESH OR FROZEN RED MEAT IS UNHEALTHY AND SHOULD BE AVOIDED

The most recent study to analyze the issue of fresh and frozen meat in relation to coronary disease and type 2 diabetes is the meta-analysis referenced below.  (A meta-analysis is a statistical way of combining a number of studies together.  Because of the increased number of subjects the results become a lot more reliable).

This study found that fresh or frozen meat presents no risk for coronary heart disease, but a slightly increased risk for diabetes.  Because the risk for diabetes was small, the authors considered the possibility that the relationship to diabetes may have been due to residual confounding.  In other words, there may have been other factors related to meat consumption that were responsible for the relationship to diabetes and that were not accounted for in the individual studies.

This does not mean, of course, that a meat-based diet is the healthiest of diets.  There are other foods that can be used instead of meat that actually reduce one's risk for heart disease, such as fish and vegetable-based protein. Nevertheless, there is no reason to feel guilty about eating a moderate amount of red meat.

Of importance - this study did find a moderate increase in risk for cardiovascular disease and type 2 diabetes from eating processed meat. Why the difference between fresh and processed meat is unclear.  The authors suggest it may be due to the sodium content of processed meats, since processed meats are very high in sodium (about 400 times the sodium content of fresh meat).  Alternatively, there may be an effect from the nitrate/nitrite preservatives in the processed meats.  I think that this is a very plausible suggestion since nitrates and their byproducts lead to dysfunction of the blood vessel wall experimentally. This may all mean, incidentally, that processed chicken, turkey, or bologna with preservatives are just as unhealthy as other processed meats - althought I know of no data on this yet. 

Reference:

Micha R et al. Unprocessed red and processed meats and risk of coronary artery disease and type 2 diabetes - an updated review of the evidence. Current Atherosclerosis Report 2012;14:515-524.