Vegetarian diets are associated with lower blood pressure and could be used as a nonpharmacological treatment, a meta-analysis of controlled trials found.
Researchers in Japan reviewed more than 100 years of published studies about vegetarian diets, which could include some dairy, eggs, fish or meat consumption. Seven clinical trials and 32 observational studies met the inclusion criteria of adults exposed to vegetarian diets as an exposure or intervention, and that tracked mean blood pressure as an outcome.
Results appeared online Feb. 24 at JAMA Internal Medicine.
In the 7 controlled trials of 311 people, vegetarian diets were associated with a reduction in mean systolic blood pressure of −4.8 mm Hg (95% CI, −6.6 to −3.1; P<0.001; I =0; P=0.45 for heterogeneity) and diastolic blood pressure of −2.2 mm Hg (95% CI, −3.5 to −1.0; P<0.001; I2=0; P=0.43 for heterogeneity) compared to omnivorous diets.
In the 32 observational studies of nearly 22,000 people, vegetarian diets were associated with lower mean systolic blood pressure of −6.9 mm Hg (95% CI, −9.1 to −4.7; P<0.001; I2=91.4; P<0.001 for heterogeneity) and diastolic blood pressure of −4.7 mm Hg (95% CI, −6.3 to −3.1; P<0.001; I2=92.6; P<0.001 for heterogeneity) compared to omnivorous diets.
The meta-analysis had a reasonably large overall sample size, and its focus on dietary patterns rather than on supplements or other dietary manipulations makes the findings easily applicable to general or clinical populations, the authors noted. Next, more research is needed into specifically which vegetarian diets were most effective.