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Meta-Analysis
. 2023 Feb;62(1):51-69.
doi: 10.1007/s00394-022-02942-8. Epub 2022 Aug 27.

Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: a systematic review and meta-analysis of prospective cohort studies

Jarle Sæby Dybvik  1 , Mette Svendsen  2   3 , Dagfinn Aune  3   4   5   6
Affiliations
Meta-Analysis

Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: a systematic review and meta-analysis of prospective cohort studies

Jarle Sæby Dybvik et al. Eur J Nutr. 2023 Feb.

Abstract

Purpose: Vegetarian diets have been associated with reduced risk of ischemic heart disease (IHD). However, results regarding cardiovascular disease (CVD) overall and stroke are less clear. We conducted a systematic review and meta-analysis of prospective cohort studies on CVD, IHD and stroke risk among vegetarians or vegans versus nonvegetarians to clarify these associations.

Methods: PubMed and Ovid Embase databases were searched through August 12, 2021. Prospective cohort studies reporting adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for incidence or mortality from CVD, IHD and stroke, comparing vegetarians and vegans to nonvegetarians were included. Risk of bias (RoB) was assessed using ROBINS-I and the strength of evidence was assessed using World Cancer Research Fund (WCRF) criteria. Summary RRs (95% CIs) were estimated using a random effects model.

Results: Thirteen cohort studies (844,175 participants, 115,392 CVD, 30,377 IHD, and 14,419 stroke cases) were included. The summary RR for vegetarians vs. nonvegetarians was 0.85 (95% CI: 0.79-0.92, I2 = 68%, n = 8) for CVD, 0.79 (95% CI: 0.71-0.88, I2 = 67%, n = 8) for IHD, 0.90 (95% CI: 0.77-1.05, I2 = 61%, n = 12) for total stroke, and for vegans vs. nonvegetarians was 0.82 (95% CI: 0.68-1.00, I2 = 0%, n = 6) for IHD. RoB was moderate (n = 8) to serious (n = 5). The associations between vegetarian diets and CVD and IHD were considered probably causal using WCRF criteria.

Conclusions: Vegetarian diets are associated with reduced risk of CVD and IHD, but not stroke, but further studies are needed on stroke. These findings should be considered in dietary guidelines.

Review registration: No review protocol registered.

Keywords: Cardiovascular disease; Ischemic heart disease; Meta-analysis; Stroke; Vegan; Vegetarian.

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Conflict of interest statement

All authors declare no conflict of interest.

Figures

Fig. 1
Fig. 1
PRISMA flowchart depicting the literature search and the inclusion/exclusion process. From: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. (2021) The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 372:n71. https://doi.org/10.1136/bmj.n71
Fig. 2
Fig. 2
Vegetarian vs. nonvegetarian diets and the risk of cardiovascular disease. AHS-1 Adventist Health Study 1, AHS-2 Adventist Health Study 2, AMS Adventist Mortality Study, EPIC-Oxford European Prospective Investigation into Cancer and Nutrition – Oxford, HBS Heidelberg Study, HFSS Health Food Shoppers Study, OVS Oxford Vegetarian Study, UKB UK Biobank
Fig. 3
Fig. 3
Vegan vs. nonvegetarian diets and the risk of cardiovascular disease, ischemic heart disease and total stroke. The summary relative risk estimate (RR) from the pooled analysis by Key et al. 1999 were based on data from 4 studies: Adventist Health Study 1, Adventist Mortality Study, Heidelberg Study, Oxford Vegetarian Study. AHS-1 Adventist Health Study 1, AHS-2 Adventist Health Study 2, AMS Adventist Mortality Study, EPIC-Oxford European Prospective Investigation into Cancer and Nutrition – Oxford, HBS Heidelberg Study, OVS Oxford Vegetarian Study
Fig. 4
Fig. 4
Vegetarian vs. nonvegetarian diets and the risk of ischemic heart disease. AHS-1 Adventist Health Study 1, AHS-2 Adventist Health Study 2, AMS Adventist Mortality Study, EPIC-Oxford European Prospective Investigation into Cancer and Nutrition – Oxford, HBS Heidelberg Study, HFSS Health Food Shoppers Study, OVS Oxford Vegetarian Study, UKB UK Biobank
Fig. 5
Fig. 5
Vegetarian vs. nonvegetarian diets and the risk of total stroke. AHS-1 Adventist Health Study 1, AMS Adventist Mortality Study, EPIC-Oxford European Prospective Investigation into Cancer and Nutrition – Oxford, HBS Heidelberg Study, HFSS Health Food Shoppers Study, HPFS Health Professionals Follow-up Study, NHS1 Nurses’ Health Study 1, NHS2 Nurses’ Health Study 2, OVS Oxford Vegetarian Study, TCHS Tzu Chi Health Study, TCVS Tzu Chi Vegetarian Study, UKB UK Biobank
Fig. 6
Fig. 6
Vegetarian vs. nonvegetarian diets and the risk of ischemic and hemorrhagic stroke. EPIC-Oxford European Prospective Investigation into Cancer and Nutrition – Oxford, TCHS Tzu Chi Health Study, TCVS Tzu Chi Vegetarian Study
See this image and copyright information in PMC

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