A new set of studies published Monday in the Annals of Internal Medicine doubts the widespread recommendations to decrease consumption of red and processed meats.
A panel of scientists, many of whom are not nutrition experts, at the leading medical journal have also issued a new recommendation, according to the guideline paper, that reads:
The panel suggests adults continue current processed meat consumption.1
In other words, they said there is no need to cut back on meat consumption. What?
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Countless nutrition experts disagree (including the American Cancer Society and the American Heart Association) and say this conclusion goes against a large body of evidence, from decades of research and studies, that has determined that, over time, individuals who eat less red and processed meat, have lower rates of death from certain cancers (including colorectal cancer) and heart disease.
Christopher Gardner, a nutrition scientist and professor of medicine at Stanford University, said he was “outraged and bewildered,” adding “this will do a disservice to the public.” Gardner says that offering up a new haphazard guideline will confuse people. Frank Hu, the chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health, agreed, saying:
This is perplexing, given the … clear evidence for harm associated with high red meat intake. The publication gives an impression of a major scientific breakthrough, but this is clearly not the case.1
Hu and Gardner are among a group of scientists who signed a letter to the journal’s editor asking the papers be held pending further review.
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Others experts include Dariush Mozaffarian, the dean of the Friedman School of Nutrition at Tufts University, as well as Eric Rimm and Dr. Walter Willett, also of Harvard’s T.H. Chan School of Public Health.1
However, the authors of the new papers published in Annals don’t agree and are not convinced that red and processed meats are associated with higher health risks. They cite weak recommendations based on little evidence.
To reach their conclusion, the authors of the new analyses used an alternative method called GRADE to assess the data. GRADE is a study process which uses a randomized controlled trial (RCT) as high-quality evidence.
The problem with using GRADE, according to Harvard nutrition scientist Frank Hu is that it was developed for evaluating evidence from drug trials, adding:
It’s really problematic and inappropriate to use GRADE to evaluate nutrition studies.1
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Nutrition science is founded on observational studies conducted by tracing the eating habits of people over several years. But the GRADE system regards these observational studies to be mediocre. Does comparing our diets to drugs makes sense? According to NPR:
The impact of eating a meat-centric diet is tricky to measure. Unlike a pill — which can be measured against a placebo in a short-term trial — our diets are much more complicated. What we eat today may influence our health over decades. And, teasing out an independent effect is tougher, because our diets are varied and complex.
If a pill leads to an improvement over a placebo, scientists can conclude that the pill is efficacious. But if you try to use this same model with diet, you can’t isolate the effects of say, just meat — or just processed meat — because we eat so many different things as part of our diets. So, therefore, critics say the drug evaluation model is not a good fit.1
So where does this leave us, the eaters who are striving to make sound choices? Bradley Johnston, one of the authors of the new analyses, says:
There may be a benefit [from] reducing your intake of red or processed meat, and people should know that. On the other hand, “there may not be a benefit at all. We’re uncertain.1
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Previously, Johnston authored a study, also published in the Annals of Internal Medicine, that questioned the quality of the evidence behind the recommendations to restrict sugar. (Really?) According to NPR:
That paper, published online in 2016, was funded by the International Life Sciences Institute, a nonprofit group funded by large food and beverage companies that has come under scrutiny for its role in shaping food policy.1
When NPR asked Johnston what kind of study it would take to provide compelling evidence that reducing red meat consumption can reduce health risks, he said:
It would take a lot of money … and it should be based on randomized trials.1
Harvard’s Rimm says Johnston’s logic is completely absurd, adding:
Can you imagine the cost if you had to … give patients red meat almost every day for a decade and then convince the other group … not to eat meat for a decade?1
Dr. Christine Laine, editor of Annals of Internal Medicine, says she agrees it would be tough to carry out such a study, telling NPR:
We’re not going to be able to do a randomized controlled trial that is going to definitely answer this question.1
Nonetheless, she supported the decision to publish the new analyses and recommendation. She also approved of the use of the GRADE evaluation system, agreeing with the authors that the evidence behind cutting back on red and process meats is not as strong as people may have been led to believe. She says:
We should just be transparent. I think we should be honest with the public that we don’t really know.
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Hu, Gardner, and the countless other nutrition experts say there is already a consensus:
To improve both human health and environmental sustainability, it is important to adopt dietary patterns that are high in healthy plant-based foods and relatively low in red and processed meats.1
