Meta-analysis of Vegetarian Diets and Incident Cardiovascular Outcomes

NCT ID: NCT03610828

Last Updated: 2018-08-01

Basic Information

• Recruitment Status: UNKNOWN
• Total Enrollment: 1 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2017-10-01
• Study Completion Date: 2018-11-01

Brief Summary

Vegetarian and vegan diets have been shown to reduce cardiometabolic risk factors for chronic diseases, such as cardiovascular disease and diabetes, and have been associated with decreased risk of these chronic diseases. The role of vegetarian and/or vegan dietary patterns and incident cardiovascular outcomes still remains unclear. To address these uncertainties, the investigators propose to conduct a systematic review and meta-analysis of the totality of evidence from prospective cohort studies to distinguish the association of vegetarian and/or vegan dietary patterns on the prevention and management of cardiovascular diseases. This proposed knowledge synthesis was commissioned by the Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD) and will be used to inform clinical practice and dietary guidelines, help improve health outcomes, and guide future research design.

Detailed Description

Background: Cardiovascular disease (CVD) is the number 1 cause of death worldwide, representing 31% of all deaths. Vegetarian and/or vegan dietary patterns have been shown in prospective cohort and cross-sectional studies to be associated with lower coronary heart disease and ischemic heart disease risk. Evidence from randomized controlled trials also suggest that vegetarian and vegan diets may be beneficial for cardiovascular disease risk factors, such as LDL cholesterol, weight, blood pressure and type 2 diabetes (glycemic control). Moreover, evidence from meta-analyses of prospective cohort studies have shown that diets high in red and processed meat consumption are associated with an increased incidence of stroke and cardiovascular mortality. The evidence for a vegetarian dietary pattern is promising for prevention and management of cardiovascular diseases, however, not all CVD guidelines recommend following a vegetarian and/or vegan dietary pattern for the prevention and management of these diseases, or the guidelines grade the evidence as low quality.

Need for proposed research: High quality systematic reviews and meta-analyses of prospective cohort studies represent evidence to support dietary guidelines and public health policy development. As dietary guidelines and public health policy have shifted toward food and dietary-pattern based recommendations, there is a need for systematic reviews and meta-analyses comparing the role of vegetarian/vegan diets in the prevention and management of cardiovascular diseases.

Objective: The investigators will conduct a systematic reviews and meta-analysis to assess vegan/vegetarian diets with cardiovascular disease outcomes (cardiovascular disease (CVD), coronary heart disease (CHD) and stroke incidence and mortality) in prospective cohort studies.

Design: The planning and conduct of the proposed meta-analyses will follow the Cochrane handbook for systematic reviews of interventions. The reporting will follow the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines.

Data sources: MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials databases will be searched using appropriate search terms supplemented by hand searches of references of included studies.

Data extraction: Two or more investigators will independently extract relevant data and assess risk of bias using the Newcastle-Ottawa Scale (NOS) for observational studies. Risk ratios, odds ratios and hazard ratios for clinical outcomes will be extracted or derived from clinical event data across exposure to either vegetarian or non-vegetarian diets. All disagreements will be resolved by consensus.

Outcomes: Six outcomes will be assessed: CVD incidence and mortality, coronary heart disease (CHD) incidence and mortality, stroke incidence and mortality

Data synthesis: The natural log-transformed relative risks or hazard ratios of clinical outcomes comparing the exposure to the reference group from each cohort will be pooled using the generic inverse variance method with random effects models. Heterogeneity will be assessed by Cochrane's Q and quantified by I2. Sensitivity analyses and a priori subgroup analyses will be undertaken to explore sources of heterogeneity including the effect of the cohorts, sex, type of vegetarian diet, underlying disease status, follow-up (<10-years, >=10-years), level of adjustment of models, quality of the studies (NOS), and validation of the dietary assessment instruments. Significant unexplained heterogeneity will be investigated by additional post hoc subgroup analyses. Meta-regression analyses will assess the significance of subgroups analyses. Publication bias will be assessed by the inspection of funnel plots and using Begg's and Egger's tests.

Evidence Assessment: The certainty of the evidence for each outcome will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Knowledge translation plan: The results will be disseminated through interactive presentations at local, national, and international scientific meetings and publication in high impact factor journals. Target audiences will include the public health and scientific communities with interest in nutrition, cardiovascular diseases and diabetes. Feedback will be incorporated and used to improve the public health message and key areas for future research will be defined. Applicant/Co-applicant Decision Makers will network among opinion leaders to increase awareness and participate directly as committee members in the development of future guidelines.

Significance: The proposed project will aid in knowledge translation related to the role of vegetarian/vegan diets in the prevention and management of cardiovascular diseases, strengthening the evidence-base for guidelines and improving health outcomes by educating healthcare providers and patients, stimulating industry innovation, and guiding future research design.

Conditions

Cardiovascular Diseases; Coronary Heart Disease; Stroke; Mortality

Study Design

• Observational Model Type: OTHER
• Study Time Perspective: PROSPECTIVE

Interventions

Vegetarian or Vegan Diets

Diets that omit all animal products (vegan diet) or all animal products with the exception of eggs and/or dairy products (vegetarian)

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Prospective cohorts studies
• Duration >=1 year
• Assessment of the exposure of vegetarian or vegan diet
• Ascertainment of viable data by level of exposure

Exclusion Criteria

• Ecological, cross-sectional, retrospective observational studies, clinical trials and non-human studies
• Duration < 1 year
• No assessment of exposure of vegetarian/vegan diet
• No ascertainment viable clinical outcome data by level of exposure

• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Canadian Institutes of Health Research (CIHR)

OTHER_GOV

Sponsor Role: collaborator

University of Toronto

OTHER

Sponsor Role: lead

Responsible Party

John Sievenpiper

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

John Sievenpiper, PhD, MD

Role: PRINCIPAL_INVESTIGATOR

University of Toronto

Locations

The Toronto 3D (Diet, Digestive tract and Disease) Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital

Toronto, Ontario, Canada

Countries

Canada

References

Satija A, Bhupathiraju SN, Spiegelman D, Chiuve SE, Manson JE, Willett W, Rexrode KM, Rimm EB, Hu FB. Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults. J Am Coll Cardiol. 2017 Jul 25;70(4):411-422. doi: 10.1016/j.jacc.2017.05.047.

Reference Type: BACKGROUND

PMID: 28728684 (View on PubMed)

World Health Organization. (2017). Cardiovascular Diseases. Obtained from: http://www.who.int/mediacentre/factsheets/fs317/en/

Reference Type: BACKGROUND

Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017 Nov 22;57(17):3640-3649. doi: 10.1080/10408398.2016.1138447.

Reference Type: BACKGROUND

PMID: 26853923 (View on PubMed)

Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Jaster B, Seidl K, Green AA, Talpers S. A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care. 2006 Aug;29(8):1777-83. doi: 10.2337/dc06-0606.

Reference Type: BACKGROUND

PMID: 16873779 (View on PubMed)

Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Green A, Ferdowsian H. A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial. Am J Clin Nutr. 2009 May;89(5):1588S-1596S. doi: 10.3945/ajcn.2009.26736H. Epub 2009 Apr 1.

Reference Type: BACKGROUND

PMID: 19339401 (View on PubMed)

Mishra S, Xu J, Agarwal U, Gonzales J, Levin S, Barnard ND. A multicenter randomized controlled trial of a plant-based nutrition program to reduce body weight and cardiovascular risk in the corporate setting: the GEICO study. Eur J Clin Nutr. 2013 Jul;67(7):718-24. doi: 10.1038/ejcn.2013.92. Epub 2013 May 22.

Reference Type: BACKGROUND

PMID: 23695207 (View on PubMed)

Wang X, Lin X, Ouyang YY, Liu J, Zhao G, Pan A, Hu FB. Red and processed meat consumption and mortality: dose-response meta-analysis of prospective cohort studies. Public Health Nutr. 2016 Apr;19(5):893-905. doi: 10.1017/S1368980015002062. Epub 2015 Jul 6.

Reference Type: BACKGROUND

PMID: 26143683 (View on PubMed)

Yang C, Pan L, Sun C, Xi Y, Wang L, Li D. Red Meat Consumption and the Risk of Stroke: A Dose-Response Meta-analysis of Prospective Cohort Studies. J Stroke Cerebrovasc Dis. 2016 May;25(5):1177-1186. doi: 10.1016/j.jstrokecerebrovasdis.2016.01.040. Epub 2016 Feb 27.

Reference Type: BACKGROUND

PMID: 26935118 (View on PubMed)

Coutts SB, Wein TH, Lindsay MP, Buck B, Cote R, Ellis P, Foley N, Hill MD, Jaspers S, Jin AY, Kwiatkowski B, MacPhail C, McNamara-Morse D, McMurtry MS, Mysak T, Pipe A, Silver K, Smith EE, Gubitz G; Heart, and Stroke Foundation Canada Canadian Stroke Best Practices Advisory Committee. Canadian Stroke Best Practice Recommendations: secondary prevention of stroke guidelines, update 2014. Int J Stroke. 2015 Apr;10(3):282-91. doi: 10.1111/ijs.12439. Epub 2014 Dec 23.

Reference Type: BACKGROUND

PMID: 25535808 (View on PubMed)

Anderson TJ, Gregoire J, Pearson GJ, Barry AR, Couture P, Dawes M, Francis GA, Genest J Jr, Grover S, Gupta M, Hegele RA, Lau DC, Leiter LA, Lonn E, Mancini GB, McPherson R, Ngui D, Poirier P, Sievenpiper JL, Stone JA, Thanassoulis G, Ward R. 2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult. Can J Cardiol. 2016 Nov;32(11):1263-1282. doi: 10.1016/j.cjca.2016.07.510. Epub 2016 Jul 25.

Reference Type: BACKGROUND

PMID: 27712954 (View on PubMed)

Glenn AJ, Viguiliouk E, Seider M, Boucher BA, Khan TA, Blanco Mejia S, Jenkins DJA, Kahleova H, Rahelic D, Salas-Salvado J, Kendall CWC, Sievenpiper JL. Relation of Vegetarian Dietary Patterns With Major Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Cohort Studies. Front Nutr. 2019 Jun 13;6:80. doi: 10.3389/fnut.2019.00080. eCollection 2019.

Reference Type: DERIVED

PMID: 31263700 (View on PubMed)

Other Identifiers

DNSG-Vegetarian diets (cohort)

Identifier Type: -

Identifier Source: org_study_id