4 Things You Should Know About the Annals of Internal Medicine Red Meat Study

By Maris Altieri RD, LMP Coordinator

Two months ago, a privately funded organization, known as NutriRECS, proposed revisions to the Dietary Guidelines for Americans concerning meat intake. Contrary to the World Cancer Research Fund’s recommendations of reducing red meat consumption to three portions per week (12-18 oz total) and limiting processed meat consumption¹, the NutriRECS authors suggest that adults should continue current unprocessed and processed red meat consumption. This publication contradicts the large body of evidence that demonstrates high red meat consumption is associated with cardiovascular disease, type 2 diabetes, colorectal cancer, and even premature death. 

Does the study provide enough evidence to completely disregard current red meat recommendations? Not quite. Before running to the grocery store and cleaning out the beef aisle, here are four things you should know about the Annals of Internal Medicine red meat review: 

1. They discarded their own meta-analyses showing increased risks of chronic diseases and total mortality

Statistical analyses that combine the results of multiple scientific studies, known as meta-analyses, in the NutriRECS report illustrated that reductions in red and processed meat are associated with²: 

• 13% lower risk of premature death
• 14% reduction in cardiovascular mortality
• 14% reduction in non-fatal stroke
• 24% reduction in type 2 diabetes
• 10% reduction in overall cancer incidence
• 11% reduction in cancer mortality

And yes, all of these values are statistically significant (unlikely due to chance). However, the GRADE methodology, which is used to assess the quality of evidence, marked these values as low to very-low certainty evidence because they came from observational studies, not randomized control trials. While randomized control trials are generally the gold-standard for medical studies, they are very difficult to design for diet research. It’s not feasible to require subjects to eat a specific diet in a controlled environment for an extended period of time.

Although observational studies can only show correlation and not causation, they are essential for nutrition research. In fact, most nutrition research use observational study designs because they look at large groups of people over time to determine patterns between diets (e.g. amount of meat consumption) and health (e.g. prevalence of heart disease).

2. Questionable speculation of risk vs. reward

The NutriRECS report recommends a maintenance in current unprocessed and processed red meat consumption because omnivores like meat and are unwilling to make dietary changes. In their report they write, “the panel believed that for the majority of individuals, the desirable effects (a potential lowered risk for cancer and cardiometabolic outcomes) associated with reducing meat consumption probably do not outweigh the undesirable effects (impact on quality of life, burden of modifying cultural and personal meal preparation and eating habits).”³ 

Dr. Katilyn Mascatelli, Phipps’ Ecopsychology Research Scientist, chimes in, “I would point out that the authors' statement about these health benefits probably not outweighing the fact that people like meat is speculative. Because the authors don't have any scientific evidence about what people would do with this information (for example, how they make decisions about how much meat to eat given this evidence), I think it's premature to make this claim."

3. Key nutrition research studies were omitted from the analysis

Large, well-known research such as the PREDIMED and DASH studies were not included in the NutriRECs analysis. NutriRECS also excluded research comparing health outcomes of vegetarians to meat eaters. 

The DASH and PREDIMED studies contribute much of the scientific basis for the Dietary Guidelines for Americans. To date, the PREDIMED remains the largest dietary intervention trial to assess the impact of the Mediterranean diet in relation to cardiovascular disease prevention. A consistent body of research has found that DASH lowers blood pressure, a factor of heart disease, for people with high blood pressure. Including these studies would undeniably change the data to favor red meat reduction.

4. The environmental impact of red and processed meat intake was not considered

Environmental degradation through food production is inextricably linked to human health. According to the Proceedings of the National Academy of Sciences of the United States of America (PNAS), producing a serving of unprocessed red meat has the highest environmental impact for scarcity-weighted water use, acidification, eutrophication, land use, and greenhouse gas emissions, which all contribute to the climate change crisis.⁴  Severe adverse consequences of climate change include rises in human mortality, morbidity, conflict and food insecurity.⁵ Yet, the authors state that consideration of environmental impacts of red meat consumption are “out of scope” of their recommendations. 

So what guidelines should I follow? Let’s Move Pittsburgh suggests referring to the 2015-2020 Dietary Guidelines and Harvard Healthy Eating Plate for general, evidence-based nutrition recommendations.

References:

1. World Cancer Research Fund . (2019, August 15). Limit red and processed meat. Retrieved from https://www.wcrf.org/dietandcancer/recommendations/limit-red-processed-meat.
2. Vernooij, R. W., Zeraatkar, D., Han, M. A., Dib, R. E., Zworth, M., Milio, K., … Johnston, B. C. (2019). Patterns of Red and Processed Meat Consumption and Risk for Cardiometabolic and Cancer Outcomes. Annals of Internal Medicine, 171(10), 732. doi: 10.7326/m19-1583
3. Johnston, B. C., Zeraatkar, D., Han, M. A., Vernooij, R. W., Valli, C., Dib, R. E., … Guyatt, G. H. (2019). Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium. Annals of Internal Medicine, 171(10), 756. doi: 10.7326/m19-1621
4. Vernooij, R. W., Zeraatkar, D., Han, M. A., Dib, R. E., Zworth, M., Milio, K., … Johnston, B. C. (2019). Patterns of Red and Processed Meat Consumption and Risk for Cardiometabolic and Cancer Outcomes. Annals of Internal Medicine, 171(10), 732. doi: 10.7326/m19-1583
5. M., M. Campos, R.Warren, J. Birkmann, G. Luber, B. O’Neill, and K. Takahashi, 2014: Emergent risks and key vulnerabilities. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1039-1099.