A day after one of the most prestigious medical journals in the country declared the evidence against red meat to be small and weak, howls of protest rang out from the Harvard T.H. Chan School of Public Health, the American Heart Association, the American Cancer Society, and a host of other organizations aligned around the longstanding message that eating red meat will increase your risk of heart disease and cancer.
The science, it now appears, was never quite there to make those claims.
The charges that only weak evidence existed against beef were first raised on Tuesday, Oct. 1, as a global consortium of 19 researchers from seven countries issued four papers in the Annals of Internal Medicine. This so-called NutriRECS Consortium, whose members were selected for their lack of conflicts of interest and skill in evaluating the quality of scientific evidence, undertook a systematic review of the content and quality of hundreds of studies involving millions of subjects, research purporting to show the harms of eating red meat.
That evidence may have been buried in journals all these years, but its conclusions have changed the way Americans eat. As a result of the longstanding advice to curtail the consumption of red meat, Americans have cut back heartily on steaks, hamburgers and roasts over the last three decades, eating nearly 28 percent less as of 2014 according to federal food availability surveys . During this same period, an era in which diabetes and obesity has skyrocketed, consumption of replacement meats chicken and pork has risen, as has that of processed foods. Critics say that widespread dietary shifts like these highlight the unintended consequences of any formal pronouncements on foods to be avoided in the name of health.
The NutriRECS researchers arrived at their conclusions after organizing the collected dietary literature on red meat and health according to a widely-accepted system for ranking scientific evidence known as GRADE. Among its methods, GRADE weights the findings of randomly controlled dietary trials more heavily than those of observational studies commonly produced to show a link between meat and illness, evidence filled with confounding variables like the truthfulness of dietary logs and the tendency of people who follow diets to undertake other health promoting behaviors. GRADE also places a higher value on findings from studies that are not funded by private interests.
Critics have long asserted that the Dietary Guidelines and their prohibitions against meat are not based on the best evidence.
"The belief that red meat causes ill-health has long been based on weak, unreliable science," said Nina Teicholz, executive director of the Nutrition Coalition in an email to Forum News Service. "Our nutritional experts have unfortunately grown accustomed to relying on this kind of unreliable observational science, but now there's a movement to move towards more solid, rigorous evidence."
"In the same way that we've seen authorities move away from the low-fat diet and caps on dietary cholesterol," she added, "after consulting more rigorous science, now we are seeing the same thing happen with red meat. Although the flip-flopping is disorienting, having advice based — finally — on sound science should come as a relief."
Among critics of red meat, the protest has been swift, heated and at times hyperbolic. Meat critic Dr. David Katz compared the paper to terrorism.
The Physicians Committee for Responsible Medicine, a vegetarian-promoting health advocacy organization, took the extraordinary step of filing a complaint with the Federal Trade Commission against the journal which published the papers.
The next installment of Dietary Guidelines for Americans are scheduled to be released in 2020. The guideline committee members have already gathered their evidence, much of it from the same pool of studies evaluated by the NutriRECS Consortium and found to be wanting.