A RED MEAT ISSUE FLAMES UP
Five – yes, five – papers in the Annals of Internal Medicine
published in October 2019 whipped up a flaming hot controversy about
nutrition guidance broadly and red meat specifically reports
ConscienHealth’s Ted Kyle. The bottom line from all these papers? Maybe
we need to admit that the evidence for harm to health from red meat is
not so hard and fast as some people like to think.
Using GRADE criteria, the certainty about the effects of red meat
on health is low. Thus, recommendations to eat less red meat for better
health are weak. In other words, there are indeed different and valid
ways to look at the issue of red meat in the diet.
Harvard’s
Frank Hu doesn’t like applying GRADE standards to nutrition advice.
“It’s really problematic and inappropriate to use GRADE to evaluate
nutrition studies,” he says. One big problem he has with the GRADE
system is that it takes randomized, controlled studies to be the gold
standard of evidence. Observational data provides weaker evidence. Such
thinking is OK for evaluating drugs. But he wrote in 2015 that the
standard should be different for nutritional epidemiology: “Some
researchers consider RCTs as the be-all and end-all of causal inference.
This sentiment may be appropriate in the pharmaceutical industry, but
the drug trial paradigm cannot be readily translated for use in the
nutritional sciences.”
However, it’s worth saying that
standards for scientific rigor were not invented by the pharmaceutical
industry. The lead on one of these five papers, Bradley Johnston,
explains:
“Regarding the reaction among some in the nutrition research community …
we are sympathetic to the discomfort of acknowledging the low-quality
evidence in one’s field. It seems to us, however, that pretending that
the rules of evidence differ across fields because the feasibility of
definitive studies is not possible in one’s particular field is a poor
solution to the problem. We believe it is important to apply common
standards for assessing the certainty of evidence across health-care
fields.”
So, what are we to think about red meat? The
evidence to say that we’re eating more red meat than we should for our
own health is weak. However, we do have other reasons to believe that
eating less red meat would be a good thing. Red meat is pretty hard on
this planet we share. A little red meat probably won’t kill you. But too
much of it might indirectly contribute to killing lots of people
through climate change.
Regardless of those facts,
opinions and feelings will drive behaviour. Some people are really
attached to the red meat in their diets. Others have strong passions for
avoiding it.
It’s not easy to be objective about
nutrition, but it’s worth a try. Dennis Bier explained this to the New
York Times: “The rules of scientific proof are the same for physics as
for nutrition.”
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