Dena Zeraatkar, MSc; Mi Ah Han, MD, PhD; Gordon H. Guyatt, MD, MSc; Robin W.M. Vernooij, PhD; Regina El Dib, PhD; Kevin Cheung, MD, MSc; Kirolos Milio, BSc; Max Zworth, BASc; Jessica J. Bartoszko, HBSc; Claudia Valli, MSc; Montserrat Rabassa, PhD; Yung Lee, BHSc; Joanna Zajac, PhD; Anna Prokop-Dorner, PhD; Calvin Lo, BHSc; Malgorzata M. Bala, PhD; Pablo Alonso-Coello, MD, PhD; Steven E. Hanna, PhD; Bradley C. Johnston, PhD
Acknowledgment: The authors thank Thomasin Adams-Webber (Hospital for Sick Children) for her help in designing the search strategy.
Disclosures: Dr. El Dib received a São Paulo Research Foundation (FAPESP) (2018/11205-6) scholarship and funding from the National Council for Scientific and Technological Development (CNPq) (CNPq 310953/2015-4) and the Faculty of Medicine, Dalhousie University. Authors not named here have disclosed no conflicts of interest. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M19-0655.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that her spouse has stock options/holdings with Targeted Diagnostics and Therapeutics. Darren B. Taichman, MD, PhD, Executive Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Catharine B. Stack, PhD, MS, Deputy Editor, Statistics, reports that she has stock holdings in Pfizer, Johnson & Johnson, and Colgate-Palmolive. Christina C. Wee, MD, MPH, Deputy Editor, reports employment with Beth Israel Deaconess Medical Center. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Yu-Xiao Yang, MD, MSCE, Deputy Editor, reports that he has no financial relationships or interest to disclose.
Reproducible Research Statement:Study protocol: Registered with PROSPERO (CRD42017074074). Statistical code and data set: Available from Ms. Zeraatkar (e-mail, email@example.com). For sample code, see Supplement 2.
Corresponding Author: Bradley C. Johnston, PhD, Department of Community Health and Epidemiology, Faculty of Medicine, Dalhousie University, Room 404, 5790 University Avenue, Halifax, Nova Scotia B3J 0E4, Canada; e-mail, firstname.lastname@example.org.
Current Author Addresses: Ms. Zeraatkar, Drs. Guyatt and Hanna, and Ms. Bartoszko: Department of Health Research Methods, Evidence, and Impact, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
Dr. Han: Department of Preventive Medicine, College of Medicine, Chosun University, 309 Philmun-daero, Dong-gu, Gwangju 61452, Korea.
Dr. Vernooij: Department of Research, Netherlands Comprehensive Cancer Organisation, Godebaldkwartier 419, Utrecht 3511 DT, the Netherlands.
Dr. El Dib: Institute of Science and Technology, São José dos Campos, Avenida Engenheiro Francisco José Longo, 777, Jardim São Dimas, São José dos Campos, 12245-000, Spain.
Dr. Cheung: 114 Loganberry Crescent, Toronto, Ontario M2H 3H1, Canada.
Mr. Milio: 592 Regal Place, Waterloo, Ontario N2V 2G3, Canada.
Mr. Zworth: 28 York Downs Drive, Toronto, Ontario M3H 1J1, Canada.
Ms. Valli and Drs. Rabassa and Alonso-Coello: Iberoamerican Cochrane Centre, (IIB Sant Pau-CIBERESP), Carrer de Sant Antoni Maria Claret, 167, Barcelona, 08025, Spain.
Mr. Lee: 30 White Lodge Crescent, Richmond Hill, Ontario L4C 9A1, Canada.
Drs. Zajac, Prokop-Dorner, and Bala: Jagiellonian University, Kopernika 7 Street, 31-034 Krakow, Poland.
Mr. Lo: 556 Amarone Court, Mississauga, Ontario L5W 0A7, Canada.
Dr. Johnston: Department of Community Health and Epidemiology, Faculty of Medicine, Dalhousie University, Room 404, 5790 University Avenue, Halifax, Nova Scotia B3J 0E4, Canada.
Author Contributions: Conception and design: D. Zeraatkar, G.H. Guyatt, M.M. Bala, P. Alonso-Coello, S.E. Hanna, B.C. Johnston.
Analysis and interpretation of the data: D. Zeraatkar, M.A. Han, R.W.M. Vernooij, K. Milio, M. Rabassa, A. Prokop-Dorner, M.M. Bala, P. Alonso-Coello, S.E. Hanna, B.C. Johnston.
Drafting of the article: D. Zeraatkar, M.A. Han, S.E. Hanna, B.C. Johnston.
Critical revision for important intellectual content: D. Zeraatkar, G.H. Guyatt, R.W.M. Vernooij, M. Rabassa, Y. Lee, A. Prokop-Dorner, C. Lo, M.M. Bala, P. Alonso-Coello, S.E. Hanna, B.C. Johnston.
Final approval of the article: D. Zeraatkar, M.A. Han, G.H. Guyatt, R.W.M. Vernooij, R. El Dib, K. Cheung, K. Milio, M. Zworth, J.J. Bartoszko, C. Valli, M. Rabassa, Y. Lee, J. Zajac, A. Prokop-Dorner, C. Lo, M.M. Bala, P. Alonso-Coello, S.E. Hanna, B.C. Johnston.
Statistical expertise: D. Zeraatkar, S.E. Hanna, B.C. Johnston.
Administrative, technical, or logistic support: D. Zeraatkar, R. El Dib, Y. Lee, S.E. Hanna, B.C. Johnston.
Collection and assembly of data: D. Zeraatkar, M.A. Han, R.W.M. Vernooij, R. El Dib, K. Cheung, K. Milio, M. Zworth, J.J. Bartoszko, C. Valli, M. Rabassa, Y. Lee, J. Zajac, C. Lo, B.C. Johnston.
Dietary guidelines generally recommend limiting intake of red and processed meat. However, the quality of evidence implicating red and processed meat in adverse health outcomes remains unclear.
To evaluate the association between red and processed meat consumption and all-cause mortality, cardiometabolic outcomes, quality of life, and satisfaction with diet among adults.
EMBASE (Elsevier), Cochrane Central Register of Controlled Trials (Wiley), Web of Science (Clarivate Analytics), CINAHL (EBSCO), and ProQuest from inception until July 2018 and MEDLINE from inception until April 2019, without language restrictions, as well as bibliographies of relevant articles.
Cohort studies with at least 1000 participants that reported an association between unprocessed red or processed meat intake and outcomes of interest.
Teams of 2 reviewers independently extracted data and assessed risk of bias. One investigator assessed certainty of evidence, and the senior investigator confirmed the assessments.
Of 61 articles reporting on 55 cohorts with more than 4 million participants, none addressed quality of life or satisfaction with diet. Low-certainty evidence was found that a reduction in unprocessed red meat intake of 3 servings per week is associated with a very small reduction in risk for cardiovascular mortality, stroke, myocardial infarction (MI), and type 2 diabetes. Likewise, low-certainty evidence was found that a reduction in processed meat intake of 3 servings per week is associated with a very small decrease in risk for all-cause mortality, cardiovascular mortality, stroke, MI, and type 2 diabetes.
Inadequate adjustment for known confounders, residual confounding due to observational design, and recall bias associated with dietary measurement.
The magnitude of association between red and processed meat consumption and all-cause mortality and adverse cardiometabolic outcomes is very small, and the evidence is of low certainty.
None. (PROSPERO: CRD42017074074)
Table 1. Summary of Findings for Unprocessed Red Meat Intake (Reduction of 3 Servings per Week) and Risk for Cardiometabolic Outcomes
Table 2. Summary of Findings for Processed Red Meat Intake (Reduction of 3 Servings per Week) and Risk for Cardiometabolic Outcomes
Nonlinear association between processed meat intake and type 2 diabetes.
The solid black line represents the point estimate, the shaded region represents the 95% CIs, and tick marks represent the positions of the study-specific estimates.
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Richard M. Fleming, PhD, MD
FHHI-OmnificImaging-Camelot El Segundo, CA, USA
October 2, 2019
Conflict of Interest:
FMTVDM patent was issued to primary author.
We Are All Now Dumber.
Atherosclerotic coronary artery disease (ASCAD) and cancer (CA) are the number 1 and 2 killers of people worldwide. Changes in dietary and lifestyle practices have undoubtedly played a major role in contributing to CA and CAD, but rather than conduct a prospective study measuring actual changes in disease [1,2], the authors  chose to do a retrospective look at studies biased towards meat consumption and concluded “The magnitude of association between red and processed meat consumption and all-cause mortality and adverse cardiometabolic outcomes is very small, and the evidence is of low certainty.” This conclusion provided immediately after noting there was “(i)nadequate adjustment for known confounders, residual confounding due to observational design, and recall bias associated with dietary measurement.”If the goal was to publish a study, which would receive media attention - the authors and journal have done just that. I wish I could reassure the general pubic and my medical colleagues that reading through the remainder of the paper produced a level of confidence in the conclusion – it does not!Both CAD and CA are associated with a series of inflammatory processes , which ultimately result in increased morbidity and mortality, missed by this retrospective review of what others have charted. This paper does a disservice to the journal, as well as medicine, the media and the general public. At a time when it is obvious that refined carbohydrates – including but not limited to sugar – as well as processed foods including meats and other foods, are a major contributor to CAD, CA, type 2 diabetes mellitus, high blood pressure and a host of other chronic inflammatory diseases, we should be conducting prospective research  into the causes and treatments of these diseases and not looking for retrospective support of bias. I am sadly reminded of these words from Billy Madison:“Mr. Madison, what you just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points and may God have mercy on your soul.” Based upon the media coverage of this paper, we are all now dumber for having read and listened to what the authors published in the Annals of Internal Medicine.Acknowledgment: FMTVDM  is issued to author.References:1. The Fleming Method for Tissue and Vascular Differentiation and Metabolism (FMTVDM) using same state single or sequential quantification comparisons. Patent Number 9566037. Issued 02/14/2017. 2. Fleming RM, Fleming MR, Chaudhuri TK. Are we prescribing the right diets and drugs for CAD, T2D, Cancer and Obesity? Int J Nuclear Med Radioactive Subs 2019;2(1):000115. 3. Zeraatkar D, Han A, Guyatt GH, et al. Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes. A Systematic Review and Meta-analysis of Cohort Studies. Ann Intern Med 2019. DOI:10.7326/M19-0655.4. Fleming RM. Chapter 64. The Pathogenesis of Vascular Disease. Textbook of Angiology. John C. Chang Editor, Springer-Verlag New York, NY. 1999, pp. 787-798.
Zeraatkar D, Han MA, Guyatt GH, et al. Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes: A Systematic Review and Meta-analysis of Cohort Studies. Ann Intern Med. 2019;:. [Epub ahead of print 1 October 2019]. doi: 10.7326/M19-0655
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Published: Ann Intern Med. 2019.
Cardiology, Coronary Risk Factors, Diabetes, Endocrine and Metabolism, Neurology.
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