[Kodos]

Journal Advice to Eat Cancer-Causing Meats: Science or Clickbait?

The Physician's Committee for Responsible Medicine weighs in and suggests this is a flawed study that is serving mostly as clickbait for the journal that it was published in. (FWIW, the PCRM was founded by Dr. Neal Barnard, who is a proponent of a plant-based, whole-food diet.)

Who is criticizing them?

Prior to publication, the Annals editor, Christine Laine, was contacted by Neal Barnard, MD, FACC, of the Physicians Committee for Responsible Medicine, who also serves on the adjunct faculty of the George Washington University, David L. Katz, MD, MPH, of Yale University, and Walter C. Willett, MD, DrPH, of the Harvard School of Public Health, who pointed out that the journal’s press release would garner widespread media attention and promote the false notion that reducing red and processed meat intake does not lead to health benefits. The editor responded, agreeing that the press release was misleading and needed to be changed, but did not distribute a corrected release to the press.

What’s wrong with the Annals articles?

Apart from the fact that the recommended dietary guidance was contrary to the identified benefits of reducing meat consumption, the articles had several methodologic problems. They left out key data, used inappropriate analyses, and allowed their own unverified guesses about public resistance to diet changes to influence their recommendations.

Missing data. Numerous key studies were excluded from the NutriRECS analysis. The PREDIMED (Prevención con Dieta Mediterránea) study was the large and well-known study that established the ability of a Mediterranean diet that replaced red meat with more healthful foods to reduce cardiovascular risk. Those whose diets tended most toward vegetarian patterns had the largest reductions in all-cause and cardiovascular mortality.

The DASH (Dietary Approaches to Stop Hypertension) study is the classic study showing that diet changes reduce blood pressure. The study’s dietary program specifically shifted the diet away from red meat toward more healthful choices.

The Lifestyle Heart Trial showed that a low-fat vegetarian diet, as part of an overall healthy lifestyle, could reverse the progression of even severe coronary heart disease. Many other randomized clinical trials—summarized in meta-analyses—have shown that replacing meat and other animal products with healthier choices consistently improves blood cholesterol, body weight, blood pressure, and blood sugar control.

Problems with analyses. In conducting its meta-analyses, the Annals articles used only the most heavily adjusted findings from the studies that were reviewed. For example, a study assessing meat’s association with heart attack risk might be adjusted for cholesterol levels, overweight, and blood pressure. However, if meat causes heart problems because it increases cholesterol, body weight, and blood pressure, adjustment for these factors could cause meat’s deleterious effects to be no longer noticeable in reported statistics. While statistical adjustments are often necessary and appropriate, if used injudiciously they obscure real findings.

Guessing about reluctance to change. Perhaps the most controversial aspect of the Annals articles was that they based their recommendations on the authors’ assumptions about people’s attitudes toward meat. The idea was that, if people enjoy meat, they should not be encouraged to eat less of it, even if it causes cancer or heart disease.

While a case can be made for adjusting recommendations to avoid violating cultural taboos, attitudes toward meat-eating are not in that category and, in fact, are already changing rapidly. Despite the massive increase in popularity of meat substitutes in recent years, the authors estimated that cultural attachment to meat is too great to be influenced by healthful recommendations.

Were that the case, the authors could have concluded that there is no benefit to encouraging people to reduce meat intake. But they went further and encouraged the public to continue current unhealthful dietary practices, despite their associations with cancer and other risks.

If guidelines reinforcing meat-eating are applied also to children and to people who are unaware of meat’s risks, the opportunity to help these populations learn healthful eating habits is forfeited.