Dena Zeraatkar, MSc; Bradley C. Johnston, PhD; Jessica Bartoszko, HBSc; Kevin Cheung, MD; Malgorzata M. Bala, MD, PhD; Claudia Valli, MSc; Montserrat Rabassa, PhD; Daegen Sit, MD; Kirolos Milio, BSc; Behnam Sadeghirad, PharmD; Arnav Agarwal, MD; Adriana M. Zea, RD; Yung Lee, BHSc; Mi Ah Han, MD, PhD; Robin W.M. Vernooij, PhD; Pablo Alonso-Coello, MD, PhD; Gordon H. Guyatt, MD; Regina El Dib, PhD
Acknowledgment: The authors thank Thomasin Adams-Webber (Hospital for Sick Children) for her help designing our search strategy.
Disclosures: Dr. Johnston received a grant from Texas A&M AgriLife Research to fund investigator-driven research related to saturated and polyunsaturated fats within the 36-month reporting period required by the International Committee of Medical Journal Editors, as well as funding received from the International Life Science Institute (North America) that ended before the 36-month reporting period. 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=M19-0622.
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
>Reproducible Research Statement: Study protocol: Available at PROSPERO (CRD42017074074). Statistical code and data set: Available from Dr. Johnston (e-mail, firstname.lastname@example.org).
Corresponding Author: Bradley C. Johnston, PhD, Department of Community Health and Epidemiology, Dalhousie University, Centre for Clinical Research, Room 404, 5790 University Avenue, Halifax, Nova Scotia B3H 1V7, Canada; e-mail, email@example.com.
Current Author Addresses: Ms. Zeraatkar, Ms. Bartoszko, Drs. Sadeghirad and Guyatt, and Ms. Perdomo: Department of Health Research Methods, Evidence, and Impact, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
Dr. Johnston: Department of Community Health and Epidemiology, Dalhousie University, Centre for Clinical Research, Room 404, 5790 University Avenue, Halifax, Nova Scotia, B3H 1V7, Canada.
Dr. Cheung: 114 Loganberry Crescent, Toronto, Ontario M2H 3H1, Canada.
Dr. Bala: Jagiellonian University Medical College, Department of Hygiene and Dietetics, 7 Kopernika Street, 31-034 Kraków, Poland.
Ms. Valli and Drs. Rabassa and Alonso-Coello: Iberoamerican Cochrane Centre, Instituto de Investigación Biomédica de Sant Pau (IIB Sant Pau-CIBERESP), Carrer de Sant Antoni Maria Claret 167, Barcelona 08025, Spain.
Dr. Sit: University of British Columbia, 107-1165 West 13th Avenue, Vancouver, British Columbia V6H 1N4, Canada.
Mr. Milio: 592 Regal Place, Waterloo, Ontario N2V 2G3, Canada.
Dr. Agarwal: Department of Medicine, University of Toronto, Suite RFE 3-805, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada.
Ms. Zea: Clinica Las Americas, Diagonal 75B, North 2A-80/140, Medellin, Colombia.
Mr. Lee: 30 White Lodge Crescent, Richmond Hill, Ontario L4C 9A1, 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 Paulo 12245-000, Brazil.
Author Contributions: Conception and design: D. Zeraatkar, B.C. Johnston, M.M. Bala, P. Alonso-Coello, G.H. Guyatt, R. El Dib.
Analysis and interpretation of the data: D. Zeraatkar, B.C. Johnston, M.M. Bala, M. Rabassa, D. Sit, M.A. Han, P. Alonso-Coello, G.H. Guyatt, R. El Dib.
Drafting of the article: B.C. Johnston, R. El Dib.
Critical revision of the article for important intellectual content: D. Zeraatkar, B.C. Johnston, M.M. Bala, D. Sit, B. Sadeghirad, A.M. Zea, Y. Lee, M.A. Han, R.W.M. Vernooij, P. Alonso-Coello, G.H. Guyatt, R. El Dib.
Final approval of the article: D. Zeraatkar, B.C. Johnston, J. Bartoszko, K. Cheung, M.M. Bala, C. Valli, M. Rabassa, D. Sit, K. Milio, B. Sadeghirad, A. Agarwal, A.M. Zea, Y. Lee, M.A. Han, R.W.M. Vernooij, P. Alonso-Coello, G.H. Guyatt, R. El Dib.
Provision of study materials or patients: B.C. Johnston, R. El Dib.
Administrative, technical, or logistic support: D. Zeraatkar, B.C. Johnston, R. El Dib.
Collection and assembly of data: D. Zeraatkar, B.C. Johnston, J. Bartoszko, K. Cheung, M.M. Bala, C. Valli, M. Rabassa, D. Sit, K. Milio, B. Sadeghirad, A. Agarwal, A.M. Zea, Y. Lee, M. Han, R.W.M. Vernooij, R. El Dib.
This article has been corrected. The original version (PDF) is appended to this article as a Supplement.
Few randomized trials have evaluated the effect of reducing red meat intake on clinically important outcomes.
To summarize the effect of lower versus higher red meat intake on the incidence of cardiometabolic and cancer outcomes in adults.
EMBASE, CENTRAL, CINAHL, Web of Science, and ProQuest from inception to July 2018 and MEDLINE from inception to April 2019, without language restrictions.
Randomized trials (published in any language) comparing diets lower in red meat with diets higher in red meat that differed by a gradient of at least 1 serving per week for 6 months or more.
Teams of 2 reviewers independently extracted data and assessed the risk of bias and the certainty of the evidence.
Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]), cardiovascular mortality (HR, 0.98 [CI, 0.91 to 1.06]), and cardiovascular disease (HR, 0.99 [CI, 0.94 to 1.05]). That trial also provided low- to very-low-certainty evidence that diets lower in red meat may have little or no effect on total cancer mortality (HR, 0.95 [CI, 0.89 to 1.01]) and the incidence of cancer, including colorectal cancer (HR, 1.04 [CI, 0.90 to 1.20]) and breast cancer (HR, 0.97 [0.90 to 1.04]).
There were few trials, most addressing only surrogate outcomes, with heterogeneous comparators and small gradients in red meat consumption between lower versus higher intake groups.
Low- to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence.
None (PROSPERO: CRD42017074074).
Table 1. Study Characteristics
Evidence search and selection.
Table 2. Summary of Findings for Lower Intake of Red Meat* and Mortality Outcomes
Richard M Fleming, PhD, MD, JD; Matthew R Fleming, BS, NRP; Tapan K Chaudhuri, MD
FHHI-OI-Camelot; Eastern Virginia Medical School
February 18, 2020
Conflict of Interest:
FMTVDM issued to first author. First author, authored the Inflammation and Heart Disease Theory.
The Food Fight over the effect red and processed meats has on Cardiovascular Disease and Cancer – Lessons Learned from our Mistakes.
Comparisons of the publications by Zhong , Rubin , and Johnston  suggests that the currently available research surrounding red and processed meats upon heart disease and cancer, leaves us with what Dyer calls a food fight ; providing little or no scientific information for physicians, patients and the media to draw upon to make informed conclusions.Merely conducting a meta-analysis of published studies looking at qualitative or semi-quantitative imaging studies, changes in weight or blood tests of various factors which contribute to coronary artery disease (CAD) or cancer – provides limited useful information about the effect of red and processed meats [5-8].If we are to clear up this confusion we must quantitatively measure the actual impact these foods have on cancer and CAD [7-9]. Admitting our mistakes can be hard!References:1. Zhong VW, Van Horn L, Greenland P, et al. Associations of Processed Meat, Unprocessed Red Meat, Poultry, or Fish Intake With Incident Cardiovascular Disease and All-Cause Mortality. JAMA Intern Med. Published online February 03, 2020. doi:10.1001/jamainternmed.2019.69692. Rubin R. Backlash Over Meat Dietary Recommendations Raises Questions About Corporate Ties to Nutrition Scientists. JAMA. Published online January 15, 2020. doi:10.1001/jama.2019.21441.3. Johnston BC, Zeraatkar D, Han MA, et al. Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium. Ann Intern Med 2019. DOI: 10.7326/M19-1621.4. Dyer O. Food fight: controversy over red meat guidelines rumbles on. BMJ 2020;368, doi.org/10.1136/bmj.m3975. Fleming RM., Kirkeeide RL, Smalling RW, Gould KL. Patterns in Visual Interpretation of Coronary Arteriograms as Detected by Quantitative Coronary Arteriography. J Am Coll. Cardiol. 1991;18:945- 951. 6. 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. 7. Fleming RM, Fleming MR, Dooley WC, Chaudhuri TK. Invited Editorial. The Importance of Differentiating Between Qualitative, Semi-Quantitative and Quantitative Imaging – Close Only Counts in Horseshoes. Eur J Nucl Med Mol Imaging. DOI:10.1007/s00259-019-04668-y. Published online 17 January 2020 https://link.springer.com/article/10.1007/s00259-019-04668-y 8. Fleming RM, Harrington GM. What is the Relationship between Myocardial Perfusion Imaging and Coronary Artery Disease Risk Factors and Markers of Inflammation? Angiology 2008;59:16-25. 9. 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.
Zeraatkar D, Johnston BC, Bartoszko J, et al. Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials. Ann Intern Med. 2019;171:721–731. [Epub ahead of print 1 October 2019]. doi: https://doi.org/10.7326/M19-0622
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Published: Ann Intern Med. 2019;171(10):721-731.
Published at www.annals.org on 1 October 2019
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