Objectives: The consumption of strict vegetarian diets with no animal products is associated with low blood pressure (BP). It is not clear whether less strict plant-based diets (PBDs) containing some animal products exert a similar effect. The main objective of this meta-analysis was to assess whether PBDs reduce BP in controlled clinical trials.
Methods: We searched Cumulative Index to Nursing and Allied Health Literature, Medline, Embase, and Web of Science to identify controlled clinical trials investigating the effect of PBDs on BP. Standardized mean differences in BP and 95% confidence intervals were pooled using a random effects model. Risk of bias, sensitivity, heterogeneity, and publication bias were assessed.
Results: Of the 790 studies identified, 41 clinical trials met the inclusion criteria (8416 participants of mean age 49.2 years). In the pooled analysis, PBDs were associated with lower SBP [Dietary Approach to Stop Hypertension -5.53 mmHg (95% confidence intervals -7.95,-3.12), Mediterranean -0.95 mmHg (-1.70,-0.20), Vegan -1.30 mmHg (-3.90,1.29), Lacto-ovo vegetarian -5.47 mmHg (-7.60,-3.34), Nordic -4.47 mmHg (-7.14,-1.81), high-fiber -0.65 mmHg (-1.83,0.53), high-fruit and vegetable -0.57 mmHg (-7.45,6.32)]. Similar effects were seen on DBP. There was no evidence of publication bias and some heterogeneity was detected. The certainty of the results is high for the lacto-ovo vegetarian and Dietary Approach to Stop Hypertension diets, moderate for the Nordic and Mediterranean diets, low for the vegan diet, and very low for the high-fruit and vegetable and high-fiber diets.
Conclusion: PBDs with limited animal products lower both SBP and DBP, across sex and BMI.