If you follow the news even a bit, you’ve probably caught wind of the latest uproar about the health impacts of eating red and processed meats. One after another news outlet, from the Washington Post, the Wall Street Journal and the New York Times to CNN, PBS and ABC have been rushing to announce the latest turnaround – and the associated fallout – in nutritional science.
The firestorm began on the first of the month when a panel of Canadian, Spanish and Polish researchers published a series of studies and a set of dietary recommendations in the Annals of Internal Medicine.
Theirs was not new research, but analyses of about 130 (whittled down from thousands) previously published observational and randomized control trials. (Stay tuned, we’ll explore the significance of these types of studies and other studies, namely double-blind placebo trials, that were noticeably absent, later on.)
Guess what? According to these new studies, it appears that it’s OK to eat red and processed meats after all.
Or is it? This radical position stands in sharp contrast to widely accepted dietary recommendations and was met swiftly with sharp and widespread opposition from the medical establishment.
In fact, the Physicians Committee for Responsible Medicine (PCRM), which advocates for whole food plant-based diets, went so far as to file a petition with the Federal Trade Commission demanding correction “false statements regarding consumption of red and processed meat.”
“These misrepresentations are directly at odds with abundant scientific evidence demonstrating the potential ill health effects of red and processed meat and the benefits of reducing consumption of red and processed meat. Abundant evidence links red and processed meat consumption to heart disease, colorectal cancer, and increased risk of premature death.
Even eating just one slice of bacon a day is linked to higher risk of colorectal cancer,” according to PCRM’s press statement.
Plant-Based Cooking spoke with Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver and co-chair of the American College of Cardiology Nutrition and Lifestyle Workgroup, and Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest, to give our readers their perspective on this latest red and processed meat controversy.
Just Ditch Existing Dietary Recommendations?
The “Annals” materials are squarely at odds with the recommendations and findings of the American Cancer Association, the U.S. Department of Agriculture, the World Health Organization, the Physicians Committee for Responsible Medicine and numerous other health organizations.
“By and large every major nonprofit professional society concerned with a particular health state, for instance, the American College of Cardiology, the American Heart Association, the American College of Lifestyle Medicine – all these different bodies have used all of the available expert evidence to craft really beautiful consensus guidelines,” Freeman said.
“In March the American College of Cardiology published its first-ever comprehensive prevention guidelines. They used all the various experts that they could find, they combed through all the literature. Basically, the conclusion is that one should eat a predominantly whole food unprocessed plant-based diet to keep away heart disease for the long term,” he said.
Consumer Dietary Confusion and Environmental Dangers
Whether it’s coffee, coconut oil, eggs, soy or animal fats, nutritional science seems all over the place sometimes, right? And that’s just one of the many concerns this controversial series of studies and upstart dietary guidelines just published in the Annals of Internal Medicine have raised.
“It’s unfortunate that these studies have gotten so much publicity because it just creates so much confusion and people are already confused about diet and health. If the studies had been published and tucked away in a journal for other scientists to look at, to read and consider, that would have been a legitimate approach to take,” Liebman said.
“They published several systematic reviews and then they published guidelines where they issued advice to the general public about eating meat. They concluded that people should continue to eat the amount of red and processed meat they’ve been eating, although they then said there was low or very low certainty for that recommendation.
To my mind, it was those guidelines that were unfortunate. Not so much that they did the analyses but issuing guidelines to the public, basically telling the public ‘Go ahead and eat as much meat as you want.’ That was irresponsible in my view,” Liebman said.
Freeman expressed similar concerns over potential impacts on public health – and the environment.
“The concern with this article is that there could be significant public health consequences if it gives people the go-ahead to eat more red and processed meats,” Freeman said. “First, there’s large bodies of evidence – much larger than this small database of articles they collected which I would argue was incomplete – suggesting that processed red meat is highly associated with the development of cancer.
In fact, the World Health Organization considers it to be in the same category of cancer-causing as cigarettes.”
“Second, for red meat, we know well that this is highly associated with heart disease, stroke, and other cardiovascular events. I don’t think it’s fair for this article to make conclusions based on relatively weak and flawed evidence and methodological approaches,” he said.
Freeman also expressed concerns about the health of the environment.
“The world climate is imperiled. The bottom line is when the U.N. says to Western developed countries, ‘Hey countries, we need you to reduce the amount of red meat you’re consuming because the environment is troubled,’ we really should pay attention,” he said.
“Ultimately we are part of our environment and our health depends on it. As our environment heats up there’s more disease, more pollution,” he said, adding that he thought it was irresponsible for the studies’ authors to separate human from environmental health.
Why Nutritional Research Is So Complicated
Nutritional research poses some unique challenges compared to pharmaceutical research in which the randomized double-blind placebo-controlled clinical trial is considered the gold standard. This type of trial is where one group of patients receives the treatment, another group receives a placebo indistinguishable from the treatment, and neither the researchers nor the patients know who is receiving what.
Just imagine doing that with diet – trying to disguise French Fries as a tossed salad?
In this case, the researchers were evaluating randomized control trials and observational studies, which are the two major methods of gathering nutritional health data, according to Leibman.
Most observational studies ask people what they eat and then follow them for years to see who gets diseases such as heart disease or cancer. Researchers also inquire about a long list of other factors that could influence results, such as exercise, smoking and alcohol consumption, she said.
Randomized control trials, on the other hand, randomly assign people to an intervention or a control group. The intervention group would be asked to follow one kind of diet and the control group would be asked to follow another kind of diet.
But of course, you don’t need to be a scientist to recognize that reliability in these types of studies can be easily compromised. As the New York Times points out, many study participants struggle to recall and report what they are actually eating. Additionally, observational studies at their best can only indicate correlation, not causation.
“This may shed some light on the fact that nutrition research needs to be better funded and we need to do more to prove our point,” Freeman said.
“Nutrition research is very difficult to do. Because unlike a drug, what you eat and how you live are very intimately intertwined, there’s a lot of confounders. It’s very hard to lock people up and force feed them a certain way, so nutrition research often has some noise, but there’s often a good signal. It’s hard to do very, very cleanly without doing things that would be less than ethical,” he said.
Back to the “Pro-Meat” Research
While the impression has been created that the “pro-meat” researchers were saying that it’s fine to eat meat without concern for health consequences, that’s not entirely accurate. What the researchers concluded was a bit more subtle – that the existing evidence for reducing consumption of red and processed meat was not strong enough to issue that recommendation, not that that evidence didn’t exist
In fact, as confusing as this may sound –“The team found that higher red meat consumption is indeed associated with increased risk of chronic disease and mortality, which mirrors what had been found by others in the past,” according to PBS NewsHour.
However, the researchers (whom Liebman called “methodologists”) relied on the GRADE system, according to PBS NewsHour “one of the hottest methods for evaluating whether you should believe past studies,” and found the studies lacking in quality.
“After you come up with your results about the evidence, you make a decision about how strong the certainty is – high, moderate, low or very low, and there’s a whole procedure for reaching one level or the other,” Liebman said.
However, as Freeman indicated earlier, there was a much larger body of evidence omitted by the researchers.
Liebman likewise said that the group didn’t look at all the evidence. There are mechanistic type studies indicating that potential carcinogens form in the gut after eating red meat and studies that show lower levels of LDL (“bad”) cholesterol when people eat less red and processed meat, for example, she said.
The Bottom Line: What Do I Eat?
Like so many others in the field, our two experts strongly advised against adopting the new recommendations and urged continuing adherence to existing dietary guidance.
“Until there’s substantially good, well-done evidence, I don’t think anyone should change what they’re doing. Rather they should continue to push themselves towards a predominantly low-fat plant-based unprocessed type of diet, not only for themselves but for the health of the planet,” Freeman said.
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