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Red meat is not a health risk. New study slams poor research

For years, studies have linked red meat consumption to health problems such as heart disease, stroke and cancer. But in the recesses of those published articles are notable limitations.

Most of the research is observational, unable to conclusively infer causation. Most are plagued by confounding variables. For example, do meat eaters simply eat less vegetables, or tend to smoke more, or exercise less? Moreover, many are based on self-reported consumption. The simple fact is that people cannot remember with any accuracy what they eat. And finally, the reported effect sizes in these scientific articles are often small. Is a supposed 15% increased risk of cancer really worth worrying about?

Study trumps lazy research

In a new, unprecedented effort, scientists at the University of Washington’s Institute for Health Metrics and Evaluation (IHME) examined decades of research on red meat consumption and its links to various health outcomes, and formulated a new rating system to communicate health risks in the process. Their findings mostly dispel any concerns about eating red meat.

“We found weak evidence of an association between unprocessed red meat consumption and colorectal cancer, breast cancer, type 2 diabetes and ischemic heart disease. Additionally, we found no evidence of an association between unprocessed red meat and ischemic stroke or hemorrhagic stroke,” they summarized.

The IHME scientists have observed the poor nature of health science for decades. Every year, hundreds of frankly lazy studies are published that simply try to find an observational link between some action—say, eating a food—and a health outcome, such as death or disease. In the end, because of sloppy methods, varying subject populations, and inconsistent statistical measures, everything, especially different foods, appears to be both and not associated with cancer. How is the lay public supposed to interpret this mess?

A new system for establishing risk

And so the researchers came up with the burden-of-evidence-risk function, a new statistical method to quantitatively “evaluate and summarize evidence of risk across different risk-outcome pairs.” Using the function, any researcher can evaluate published data for a certain health risk, and then, using the function, calculate a single number that translates to a one to five star rating system.

“A one-star rating indicates that there may be no true relationship between the behavior or condition and the health outcome. Two stars indicate that the behavior or condition is associated with at least a 0-15% change in the probability of a health outcome, while three stars indicate at least a 15-50% change, four stars indicate at least ‘ a 50-85% change, and five stars indicate a more than 85% change.”

When the IHME ran this feature on red meat consumption and its potential links to various adverse health outcomes, they found that none warranted more than a two-star rating.

“The evidence for a direct vascular risk from regular meat consumption is very low, to the point that there is probably no risk,” said Dr. Steven Novella, a Yale neurologist and president of the New England Skeptical Society, said. “However, there is more evidence for a health risk from eating too few vegetables. That’s really the risk of a high-meat diet, those meat calories displace vegetable calories.”

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The IHME team plans to use their burden of proof function on all kinds of health risks, creating a massive, freely accessible database.

“In addition to helping consumers, our analysis can guide policymakers in developing health and wellness education programs so they focus on the risk factors with the greatest impact on health,” Dr. Emmanuela Gakidou, professor of health metric sciences at IHME and a lead author of the study, said in a statement. “Health researchers can also use this analysis to identify areas where current evidence is weak and more definitive studies are needed.”

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