0
Original Investigation |

Vegetarian Diets and Blood Pressure:  A Meta-analysis

Yoko Yokoyama, PhD, MPH1,2,3; Kunihiro Nishimura, MD, PhD, MPH4,5; Neal D. Barnard, MD3,6; Misa Takegami, RN, PhD, MPH1,7; Makoto Watanabe, MD, PhD8; Akira Sekikawa, MD, PhD9; Tomonori Okamura, MD, PhD10; Yoshihiro Miyamoto, MD, PhD1,8
[+] Author Affiliations
1Department of Preventive Medicine and Epidemiologic Informatics, National Cerebral and Cardiovascular Center, Osaka, Japan
2Japan Society for the Promotion of Science, Tokyo, Japan
3Physicians Committee for Responsible Medicine, Washington, DC
4Division of Evidence-Based Medicine and Risk Analysis, Preventive Medicine and Epidemiology, National Cerebral and Cardiovascular Center, Osaka, Japan
5Department of Nephrology, School of Medicine, Fujita Health University, Aichi, Japan
6Department of Medicine, George Washington University School of Medicine and Health Sciences, Washington, DC
7Department of Healthcare Epidemiology, Kyoto University School of Medicine and Public Health, Kyoto, Japan
8Department of Preventive Cardiology, National Cerebral and Cardiovascular Center, Osaka, Japan
9Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania
10Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo, Japan
JAMA Intern Med. 2014;174(4):577-587. doi:10.1001/jamainternmed.2013.14547.
Text Size: A A A
Published online

Importance  Previous studies have suggested an association between vegetarian diets and lower blood pressure (BP), but the relationship is not well established.

Objective  To conduct a systematic review and meta-analysis of controlled clinical trials and observational studies that have examined the association between vegetarian diets and BP.

Data Sources  MEDLINE and Web of Science were searched for articles published in English from 1946 to October 2013 and from 1900 to November 2013, respectively.

Study Selection  All studies met the inclusion criteria of the use of (1) participants older than 20 years, (2) vegetarian diets as an exposure or intervention, (3) mean difference in BP as an outcome, and (4) a controlled trial or observational study design. In addition, none met the exclusion criteria of (1) use of twin participants, (2) use of multiple interventions, (3) reporting only categorical BP data, or (4) reliance on case series or case reports.

Data Extraction and Synthesis  Data collected included study design, baseline characteristics of the study population, dietary data, and outcomes. The data were pooled using a random-effects model.

Main Outcomes and Measures  Net differences in systolic and diastolic BP associated with the consumption of vegetarian diets were assessed.

Results  Of the 258 studies identified, 7 clinical trials and 32 observational studies met the inclusion criteria. In the 7 controlled trials (a total of 311 participants; mean age, 44.5 years), consumption of vegetarian diets was associated with a reduction in mean systolic BP (−4.8 mm Hg; 95% CI, −6.6 to −3.1; P < .001; I2 = 0; P = .45 for heterogeneity) and diastolic BP (−2.2 mm Hg; 95% CI, −3.5 to −1.0; P < .001; I2 = 0; P = .43 for heterogeneity) compared with the consumption of omnivorous diets. In the 32 observational studies (a total of 21 604 participants; mean age, 46.6 years), consumption of vegetarian diets was associated with lower mean systolic BP (−6.9 mm Hg; 95% CI, −9.1 to −4.7; P < .001; I2 = 91.4; P < .001 for heterogeneity) and diastolic BP (−4.7 mm Hg; 95% CI, −6.3 to −3.1; P < .001; I2 = 92.6; P < .001 for heterogeneity) compared with the consumption of omnivorous diets.

Conclusions and Relevance  Consumption of vegetarian diets is associated with lower BP. Such diets could be a useful nonpharmacologic means for reducing BP.

Figures in this Article

Sign In to Access Full Content

Don't have Access?

Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more

Subscribe for full-text access to content from 1998 forward and a host of useful features

Activate your current subscription (AMA members and current subscribers)

Purchase Online Access to this article for 24 hours

Figures

Place holder to copy figure label and caption
Figure 1.
Study Flow Diagram

Selection of clinical trials and observational studies for meta-analysis of association between vegetarian diets and blood pressure.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.
Pooled Systolic and Diastolic Blood Pressure (BP) Responses to Vegetarian Diets in Clinical Trials

Effects on systolic BP (A) and on diastolic BP (B) are depicted as squares; error bars indicate 95% CIs. Meta-analysis yielded pooled estimates of −4.8 mm Hg (95% CI, −6.6 to −3.1) for systolic BP and −2.2 mm Hg (−3.5 to −1.0) for diastolic BP, which are depicted as blue diamonds. Vegan diets were defined as omitting all animal products; vegetarian diets may include some animal products as indicated by the terms lacto (dairy products) and ovo (eggs).

Graphic Jump Location
Place holder to copy figure label and caption
Figure 3.
Pooled Systolic Blood Pressure (BP) Among Vegetarians in Observational Studies

Effects on systolic BP are depicted as squares; error bars indicate 95% CIs. Meta-analysis yielded a pooled estimate of −6.9 mm Hg (95% CI, −9.1 to −4.7) for systolic BP, which is depicted as a blue diamond. Arrows indicate that the 95% CI exceeds the left line. Vegan diets were defined as omitting all animal products; vegetarian diets may include some animal products as indicated by the terms lacto (dairy products) and ovo (eggs).

Graphic Jump Location
Place holder to copy figure label and caption
Figure 4.
Pooled Diastolic Blood Pressure (BP) Among Vegetarians in Observational Studies

Effects on diastolic BP are depicted as squares; error bars indicate 95% CIs. Meta-analysis yielded a pooled estimate of −4.7 mm Hg (95% CI, −6.3 to −3.1) for diastolic BP, which is depicted as a blue diamond. Arrows indicate that the 95% CI exceeds the left line. Vegan diets were defined as omitting all animal products; vegetarian diets may include some animal products as indicated by the terms lacto (dairy products) and ovo (eggs).

Graphic Jump Location
Place holder to copy figure label and caption
Figure 5.
Funnel Plot of Comparison of Weight and Differences in Mean Systolic Blood Pressure (BP) Associated With Consumption of Vegetarian Diets

Funnel plot of study weights against change in systolic blood pressure (BP) in clinical trials (A) and observational studies (B). Blood pressure results in individual studies are depicted as circles scattered around the pooled BP estimate. A trim-and-fill method indicated that 3 clinical trials and no observational studies might have been missing owing to publication bias. After adjustment for putative missing data, the overall differences for systolic BP increased to −5.2 mm Hg (95% CI, −6.9 to −3.5) in clinical trials.

Graphic Jump Location

Tables

References

Correspondence

CME
Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Submit a Comment

Multimedia

Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Topics
PubMed Articles
Jobs
brightcove.createExperiences();