Conflicting evidence exists on the association between a vegetarian diet (involving no or rare meat consumption) and hypertension. In this meta-analysis, the authors included 7 controlled trials and 32 observational studies examining the association between vegetarian diets and hypertension. The 7 trials included 311 individuals with a mean age of 44.5 years.  After pooling of trial results, a vegetarian diet was associated with a mean reduction in systolic blood pressure (SBP) by 4.8mmHg (95% CI 3.1 to 6.6 mmHg reduction; P<.001) and diastolic blood pressure (DBP) by 2.2 mmHg (95% CI 1.0 to 3.5 mmHg reduction; P<.001). The 32 observational studies included 21,604 individuals with a mean age of 46.6 years.  After pooling results of these observational studies, a vegetarian diet was associated with lower SBP by 6.9 mmHg (95% CI 4.7 to 9.1 mmHg lower; P<.001) and lower DBP by 4.7 mmHg (95% CI 3.1 to 6.3 mmHg lower; P<.001). Meta-regression suggested that the association between vegetarian diet and BP was stronger amongst men and those with higher baseline BP.

Conclusion: In this meta-analysis, a vegetarian diet was associated with lower blood pressure compared to omnivorous diet. However, observational studies used for the meta-analysis were all cross-sectional with significant heterogeneity in the patient populations. Additionally, adjustment for other lifestyle factors associated with a vegetarian diet and food composition could not be performed in this analysis.

 Summarized by Steven M. Bradley and Supriya Shore

•  Yokoyama Y, Nishimura K, Barnard ND, et al. Vegetarian diets and blood pressure: a meta-analysis. JAMA internal medicine. Apr 2014;174(4):577-587.