For example, Time's headline says: "Should You Stop Eating Red Meat? A New Paper Has a Controversial Answer." As always, the nutrition reporter portrays nutrition science as fickle, endlessly reversing itself.
It's not true. The actual scientific content in the new studies confirms what we already knew.
The best available evidence suggests that reducing red and processed meat consumption will reduce risk of death from cardiovascular disease and cancer.
It always is the case that nutrition scientists and communicators must accomplish two tasks:
- understand the available evidence; and
- reflect on what burden of proof should be used for nutrition policy decision making.
The new studies made atypical decisions about Task #2. For reasons that are not clear to me -- perhaps out of a scientific sense of caution or perhaps out of a bias in favor of red and processed meat -- they ramped up the burden of proof that they apply to recommendations that advise less red and processed meat. Citing research guidelines that give highest scores for pharmaceutical trials [edited slightly 4pm], they rate most of the available evidence in any direction as weak. This is not how I would have communicated the evidence. In my view, it is understandable that randomized control trials cannot be widely used on this topic, because one would have to wait too long for a sufficient number of cancers or heart attacks attributable to a meat intake intervention in a well-powered study. So, I have long accepted cohort and observational studies as the best available evidence on this topic. The new studies do pretty much the same, but they label each piece of evidence as "weak." They are free to apply these labels, and I feel free to ignore these labels.
Turning to Task #1, the studies confirm what I already knew. For example, here are my statistical interpretation sentences for several main results from the new studies.
On average, reducing weekly unprocessed red meat intake by 3 servings is associated with:
- 7% lower risk of death,
- 10% lower risk of death from cardiovascular disease,
- 6% lower risk of stroke,
- 10% lower risk of type 2 diabetes,
- 7% lower risk of death from cancer.
The list of results continues for processed meat.
If you want to describe these effects as "small" and you want dietary changes that reduce your risk by twice as much, then knock yourself out. You may reduce your red meat intake by perhaps approximately [note: qualifying adjective added 4pm] 6 servings.
If you want to describe these effects as "small" and you want dietary changes that reduce your risk by twice as much, then knock yourself out. You may reduce your red meat intake by perhaps approximately [note: qualifying adjective added 4pm] 6 servings.
I recognize that these results are accompanied by blistering disparagement of recommendations to eat less red and processed meat, but I don't trust these authors enough to place credence on their rhetorical choices. Their scientific results are what matters.
Reading these scientific results, even acknowledging the limits of our knowledge, I will continue to support existing recommendations to eat less red and processed meat. No better evidence exists.
