Do Only Processed Red Meats Promote Heart Disease?

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The answer would be yes if you relied on recent media reports of a recent study by the Harvard School of Public Health. The study was a metaanalysis of over 1,600 earlier studies. Researchers looked at the risk of developing coronary heart disease (CHD) and/or type 2 diabetes mellitus (DM) with the amount and type of meat consumed.

Dr. Reneta Micha and her colleagues found that each additional 2-ounce portion of processed meat a person consumed on average each day was associated with a 42% increased risk of experiencing a CHD event and a 19% increased risk of developing type 2 diabetes.1 This powerful new data indicates processed meats appear to be particularly dangerous.

Had the media focused on the mounting evidence that even modest amounts of processed meats greatly increase CHD risk there would be no reason to fault most of the reporting. Unfortunately, many of the media while correctly suggesting this new study added to evidence implicating the consumption of processed red meats was particularly unhealthy, they also grossly misinterpreted the reported conclusion that eating unprocessed red meats did increase the risk of CHD or type 2 DM. In fact, that conclusion should not have been drawn from Dr. Micha's data. Perhaps her conclusion that the "Consumption of processed meats, but not red meats, is associated with higher incidence of CHD and diabetes mellitus." was too easy to misinterpret for those who did not read or understand the full study?

Certainly Dr. Micha did look for an independent association between the amount of unprocessed red meat consumed and the risk of developing CHD and diabetes and found no statistically significant association.

Indeed, the data showed the relative risk for each additional serving of red meat consumed daily was 1.00 indicating that eating more unprocessed red meat did not predict a greater risk of CHD at all. Sadly many media reports interpreted this lack of positive association as demonstrating unprocessed red meats did not promote disease and so were now okay to eat. Some even told people to go ahead and fire up the BBQ because this new study shows eating more steaks, pork chops, hamburgers, and leg of lamb won't increase the risk of either heart disease or diabetes. But a closer look at the data makes it clear this was not what it showed at all.

First off, the Micha study did observe a 16% greater risk of developing type 2 DM for each 4 ounce additional portion of unprocessed red meat, which was nearly as great as the 19% increased risk seen with each 2 ounce portion of processed meat consumed. However, the statistical confidence range was larger for unprocessed red meat (0.92 to 1.46) than it was for the processed meat (1.11-1.27) so the later was statistically significant but not the former even though the size of the association/ correlation was in the same direction and of a similar size. Clearly this study cannot be comforting to those who'd prefer to believe red meat doesn't promote type 2 DM.

So why did Micha's metaanalysis fail to find an association between the consumption of unprocessed red meat intake and CHD risk even though we know that red meat is high in saturated fat and cholesterol and we know higher intakes of both raise LDLC levels and promote CHD? One obvious possibility could simply be that those people who ate less red meat simply ate more poultry and/or dairy products instead. If the people who ate less steak and burgers ate more cheese omelets, Filet-O-Fish, and roast chicken the odds are good their fat and cholesterol intake was similar to those eating more red meat and so their risk of CHD risk should also have been similar as Dr. Micha reported. Nothing in the Micha study suggests this was not the case. If this is the most likely explanation (and it is from my perspective) then this study should not have been misinterpreted as showing eating more red meat won't increase the risk of CHD or type 2 DM.

Bottom Line: There is growing reason to believe that processed meats with their high salt content and larger amount of other additives are significantly more dangerous than even unprocessed red meat when it comes to promoting CHD and possibly type 2 DM as well. Too bad the mass media couldn't have figured this out and informed people about what this study's data really does show.

By James J. Kenney, PhD, RD, FACN


1. Micha R, Wallace SK, Mozaffarian D. Red and processed meat consumption and the risk of incident coronary heart disease, stroke, and diabetes mellitus. Circulation 2010;121:2271-83 2.pdf

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