In evaluating any study alleging that eating meat will sicken and ultimately kill you, it’s critical to identify who’s doing the research and what biases they might harbor, consciously or otherwise.
Feeling good about your judicious consumption of red meat these days? Enjoying the sense of well-being that (allegedly) comes from including more fruits, vegetables and whole grains in your daily diet?
Well then I’ve got some bad news: According to yet another study receiving an inordinate volume of media coverage, “even eating small portions of red meat is risky,” the implication being that like radiation, red meat is dangerous no matter how little people consume.
Before allowing your blood pressure to spike over that allegation, it should be emphasized that this study, titled, “Red and Processed Meat and Mortality in a Low Meat Intake Population,” has a number of serious problems.
Problem No. 1: It was conducted at Loma Linda University in California, a college that’s run by the Seventh Day Adventist organization, avowed proponents of a strict vegetarian diet. For that institution to proclaim on the basis of this study that eating meat is problematic is like the Association of Public Librarians publishing a study suggesting that watching YouTube videos — even small numbers of them — as opposed to reading books runs the risk of permanently damaging one’s eyesight.
Consider the source before accepting the conclusions.
Problem No. 2 is that the data in the study were obtained from dietary recall questionnaires. Regular readers of this column hopefully recognize the serious shortcoming of such instruments. Not only do people seriously underestimate portion size, and thus calorie counts, of the meals they eat, but as is true with any self-selected set of data, the “quality” of what people say they consume is often at odds with what they actually stuff into their pie holes.
That’s not a knock on the good people who belong to the Adventist movement; it’s simply an inescapable feature of human nature: We “naturally” exaggerate the positive choices we make in life, while minimizing the less-than-admirable ones.
Survey a sample of adults as to whether they ever exceed the speed limit on the freeway, and the data will conflict wildly with any motorist’s actual experience of driving the speed limit while noticing that every car on the road passes them up!
Uncovering sample bias
All that being said, the fundamental flaw with this study goes beyond inaccurate dietary recalls or subtle biases on the part of the researchers. The truly serious problem that discredits the results is what statisticians call “population bias.”
Simply put, that means that a retrospective study that correlates lifestyle factors with morbidity and mortality data cannot be relied upon to provide valid conclusions when the people being studied do not mirror the demographics of the general population.
This particular study — as is true of most Loma Linda research — was conducted on a sample of Adventist congregation members. As most people are aware, that religion prohibits not just the consumption of animal foods, but also any use of tobacco and alcohol.
As a consequence, data on illness and death rates cannot be conflated to the larger population that doesn’t observe such proscriptions.
It doesn’t take a Ph.D. to recognize that people who “violate” the Adventist credo to refrain from ever eating meat — since they were the ones supposedly at greater risk of cardiac disease and earlier deaths — would also be more likely to also indulge in smoking or drinking, which would clearly qualify as a conflicting variable.
Not only that, but according to the Centers for Disease Controls and Prevention, approximately 25% of annual U.S. deaths are due to complications of cardiovascular disease, whereas the Loma Linda study calculated that 32.9% of the deaths in the Adventist cohort were related to cardiac conditions. That means that the population allegedly following the no-meat-never-ever diet — at least half of all Adventists claim to be vegetarians — are somewhat more likely to die from a heart attack, a stroke or complications of hypertension.
But get this: Meat-eating Adventists are less likely to succumb to cancer. The National Cancer Institute estimates that cancer death rates now are virtually identical to those of cardiovascular disease: about 33% of all U.S. deaths annually are due to cancer. Yet the death rate from cancer causes among Adventists was only 22.7%.
So, eating meat is apparently protective of cancer mortality. Stuff that fact in your veggie burgers.
One final note: According to the study’s authors themselves — and I quote: “Processed meat — modified to improve flavor through curing, smoking, or salting (such as ham and salami) — alone was not significantly associated with risk of mortality.”
And yet, how many media stories have repeated the assertion that while fresh beef or pork might not be too horribly detrimental, high-fat, sodium-loaded processed products are little more than death by deli?
Like the overall assertions of these Loma Linda researchers, turns out that so-called conventional wisdom about meat-eating might be so smart after all.
The opinions in this commentary are those of Dan Murphy, a veteran journalist and commentator.