On Monday, the Archives of Internal Medicine published a study titled “Red Meat Consumption and Mortality” and it will not surprise you to learn that when I used Google to check for the fallout, I found some 900 new stories from publications scattered around the planet.
Don’t worry, I am not going to discuss all of them here. But I do want to talk about some of the issues that arise – both positive and not so positive – as journalists and bloggers react to a report suggesting that a popular diet staple increases the risk of dying early (by an average 13 percent) and recommends “substitution of other healthy protein sources” in aid of living longer.
The study was conducted by researchers at Harvard University, which undoubtedly added to its credibility factor. But it’s important to note that this was not a controlled experiment that established a causal link between red meat and specific causes of death.
In fact, the researchers used a rather broad definition of red meat that included “unprocessed” sources such as beef, pork, and lamb as well as “processed” sources such as bacon, pepperoni, hot dogs and baloney slices. This leads the picky science writer to feel argumentative: wouldn’t there be different issues associated with eating these different products? The researchers report that mortality risks are greater with processed meats, possibly due to the chemical preservatives. But to continue being picky: Is this just a red meat issue? What about the possible chemical risks of, say, processed poultry products?
But, never mind, this is a “red meat” study. The other essential point is that the conclusions are based on observational study, specifically from data collected from self-reported questionnaires given in two large cohort studies (tracking specific groups over a period of time) dedicated to public health issues, the Health Professionals Follow-up Study (1986-2008) and the Nurses Health Study (1980-2008).
We know from past experience that such studies can offer an extremely valuable perspective on the way lifestyle impacts health. And we also know from past experience that perspective still needs to be kept in perspective and treated with due caution. Why? Well, people don’t actually always self-report accurately, as we also know, and it is often difficult to correctly filter answers in assessing results. The Nurses’ Healthy Study, for instance, was a major contributor to the idea – now disproved – that post-menopausal Hormone Replace Therapy (HRT) dramatically reduced the chance of late-life heart attacks in women.
Further, and I’d like to thank the meticulous blog, Gnolls.org, for this: a different set of Harvard researchers did a meta-analysis only two years ago which found that, indeed, processed meats seemed to increase the risk of heart disease and diabetes. But unprocessed red meat seemed to have no measurable effect at all.
Both the above mentioned post and the health-focused blog, Mark’s Daily Apple, end up being pretty dismissive on mainstream media reporting on the issue. Over at the Daily Apple, in a post titled “Will Eating Red Meat Kill You?’, writer Denise Minger neatly eviscerates the Harvard study and much of the coverage:
If you’ve been hanging around the nutrition world for very long, you’ve probably realized by now that health according to the media and health according to reality are two very different things—and even scientific studies can be misrepresented by the researchers who conduct them.
In fact, it has occurred to me in reading the story coverage, that the Harvard researchers have really been pushing the alarm buttons. As an example in this nicely-balanced story from McClatchy’s Donald Bradley, we find the study’s lead author flatly asserting: “Any red meat you eat contributes to the risk.”