Harvard chides recent guidelines recommending continued intake of red, processed meat

The Harvard T.H. Chan School of Public Health (HSPH) has released a strongly worded statement against a recent “dietary guidelines recommendation” published in Annals of Internal Medicine, which suggests that adults can continue eating red meat and processed meat at current intake levels.

“This recommendation runs contradictory to the large body of evidence indicating higher consumption of red meat—especially processed red meat—is associated with higher risk of type 2 diabetes, cardiovascular disease, certain types of cancers and premature death,” the report stated. [https://www.hsph.harvard.edu/nutritionsource/2019/09/30/flawed-guidelines-red-processed-meat/]

The HSPH consulted with experts to scrutinize the research behind the said guidelines, and one of the key takeaways was that the guidelines were “not justified” as these “contradict the evidence generated from their own meta-analyses.” In particular, three of the five published systematic reviews at the core of the recent recommendations confirmed previous findings on the association between red meat consumption and adverse health effects.

The controversial guidelines were developed by a panel of 14 members from seven countries, who used the Nutritional Recommendations (NutriRECS) guideline development process, which includes systematic review methodology, and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methods to rate the certainty of evidence for each outcome. [Ann Intern Med 2019;doi:10.7326/M19-1621]

Five systematic reviews became the basis for the said recommendations, of which four addressed the health effects associated with red meat and processed meat consumption and one addressed people’s health-related values and preferences in terms of meat intake. [Ann Intern Med 2019;doi:10.7326/M19-0655; Ann Intern Med 2019;doi:10.7326/M19-0699; Ann Intern Med 2019;doi:10.7326/M19-1326; Ann Intern Med 2019;doi:10.7326/M19-0622; Ann Intern Med 2019;doi:10.7326/M19-1583]

Based on the results of these systematic reviews, the 14-member panel suggested that “adults continue current unprocessed red meat consumption” and “current processed meat consumption.” [Ann Intern Med 2019;doi:10.7326/M19-1621]

“This assessment may be excessively pessimistic; indeed, we hope that is the case,” the panel wrote in their report. “What is certain is that generating higher-quality evidence regarding the magnitude of any causal effect of meat consumption on health outcomes will test the ingenuity and imagination of health science investigators.”

Experts from the HSPH were quick to react, saying that the publication of these studies and the meat guidelines in a medical journal was “unfortunate” due to its potential harm to public health and to the credibility of nutrition science. They added that such recommendations could erode public trust in scientific research and might lead to further “misuse of systematic reviews and meta-analyses.”

The Harvard experts even went further to say that the research was a “prime example where one must look beyond the headlines and abstract conclusions.” [https://www.hsph.harvard.edu/nutritionsource/2019/09/30/flawed-guidelines-red-processed-meat/]

“It is important for journalists, health professionals and researchers to look beyond the sensational headlines and even the abstracts of the papers to verify the evidence behind the claims,” the experts said. “It’s also crucial to understand that nutrition research is a long and evolving process, and therefore critical to look at the totality of the evidence.”

Finally, Harvard experts insisted that current recommendations on healthy and balanced eating patterns for the prevention of chronic diseases should not change.

“Existing recommendations are based on solid evidence from randomized controlled studies with cardiovascular risk factors as the outcomes, as well as long-term epidemiologic studies with cardiovascular disease, cancer, type 2 diabetes and mortality as outcomes,” the experts said.

“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,” they added.