On Sept. 30 a series of systematic reviews that used a higher standard of evidence announced a recommendation that for most people, reducing red and processed meat consumption by three servings weekly would have little to no impact on their health. This study, published in the Annals of Internal Medicine, differs from many previously publicized studies.
AgriLife Today sat down with three of the researchers who authored the study to better understand these new recommendations and discuss the importance of rigorous science in the pursuit of accurate nutritional information, and how that can benefit agriculture and health care.
Bradley C. Johnston, Ph.D., associate professor of community health and epidemiology at Dalhousie University; Gordon H. Guyatt, M.D., professor of medicine at McMaster University; and Patrick Stover, Ph.D., director of AgriLife Research and vice chancellor and dean for Agriculture and Life Sciences at Texas A&M AgriLife, were part of the NutriRECs guideline panel on red and processed meat, made up of a group of 14 panel members from seven countries. NutriRECS is an independent global network of experts in medicine, nutrition, epidemiology and public health that brings unbiased, scientific rigor to deciphering the food and health connection. The study focused exclusively on health outcomes and did not consider animal welfare or environmental issues.
Q: What exactly does this new research say?
Johnston: It differs from what has previously been recommended. Based on our four systematic reviews assessing the potential harms of red and processed meat consumption, there is only low certainty evidence of a very small reduction in cancer, diabetes and heart disease from reducing red meat and processed meat consumption. Based on these reviews, we cannot say with any certainty that reducing red meat or processed meat will prevent cancer, diabetes or heart disease.
Based on a fifth systematic review assessing health-related values and preferences of meat consumption, in general, people who choose to eat meat enjoy doing so, and may be reluctant to change their consumption patterns on the basis of uncertain, very small reductions in adverse events over long periods of time.
Based on low certainty evidence from five systematic reviews, we made a weak recommendation in favor of continuing red and processed meat consumption. The recommendation rests on the inference that the majority of fully informed people will, considering health effects alone, continue their current red meat and processed meat consumption. For most people who enjoy eating meat, the uncertain health benefits of cutting down are unlikely to be worth it.
Q: Why do these results differ from the recommendations of previous reviews and guidelines?
Guyatt: Our focus was on the individual level rather than the public health or societal level. For the individual, based on our systematic reviews, most individuals who reduce their red meat consumption will experience a decrement in quality of life with reducing, and a possible, but uncertain, very small decreased risk in cancer and cardiometabolic outcomes.
Some people may think that it is ethical to tell people– from a societal perspective, based on low certainty evidence– to stop or reduce their meat consumption, but we avoided this issue by taking an individual perspective. We think individuals should be fully informed of the certainty of evidence for the most important outcomes (cancer, diabetes, heart disease) and the very small magnitude of effect. The decision regarding reduction in red meat or processed meat consumption is value and preference sensitive (i.e. some will choose to reduce, but the majority will not).
Q: How can nutritional advice get better?
Stover: We need to produce food that nourishes people in a way that reduces people’s susceptibility to chronic disease. When you use chronic disease as the end point of analyses of the health effects of food and nutrients, it is important to use standards of evidence that are widely accepted by experts across the disciplines to ensure public trust. NutriRECS utilized international standards set forth by AGREE and the GRADE working group to assess the link between red and processed meat consumption and chronic disease.
NutriRECS used GRADE methodology to assess the certainty (or quality) of evidence for each health outcome. GRADE has been adopted by over 110 organizations worldwide and is regularly applied to observational studies. Using GRADE, high certainty (high quality) evidence can be used to establish causality, whereas low certainty evidence is only appropriate for establishing an association and for generating hypotheses. GRADE methodology is also recommended to assess evidence for establishing Dietary Reference Intakes, which include the Recommended Dietary Allowance, RDA, for nutrients, when chronic disease endpoints are used.
Q: What’s the big takeaway?
Johnston: Overall, this is not just another study on red and processed meat, but a series of five high quality systematic reviews to inform dietary recommendations, work based on publicly available study protocols; resulting in recommendations that we think are far more transparent, robust and reliable.
Q: What is the connection between agriculture and health care?
Stover: We need an integrated approach to research and to resolving the health care crisis. Food security, agriculture, environmental health and population health are interconnected – and all are fundamental to our national security now and for future generations. There is a national need for integrated research in life sciences, social science, environmental science, policy and economics to ensure better health, prosperity and sustainability of our food system. Robust evidence allows effective food and agricultural practices and policies that can play a more meaningful role in effectively reducing the costs of the nation’s health care crisis while protecting our environment.