Evidence-Based Ranking of Herbal Medicines for Hypertension Management: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Abstract

Introduction: Hypertension affects over 116 million adults in the United States and >1 billion globally, substantially contributing to cardiovascular morbidity. Herbal therapies have emerged as potential complementary treatments for blood pressure management. To the best of our knowledge, this study is the first systematic review with network meta-analysis (NMA) aimed at ranking the most effective herbal therapies for lowering blood pressure. Methods: We systematically searched MEDLINE, Embase, Cochrane CENTRAL, and Cochrane Database of Systematic Reviews (CDSR), selecting randomized controlled trials (RCTs) enrolling hypertensive and prehypertensive adults that compare herbal medicine interventions to placebo, usual care, or against each other. We used the Cochrane RoB 2 tool to assess the risk of bias. We performed frequentist random-effects network meta-analyses and summarized effects as mean differences (MD) with 95 % confidence intervals (CI). We evaluated the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. Results: A total of 47 RCTs involving 3,559 patients met prespecified eligibility criteria. Our NMA indicates that Celery (Apium graveolens) reduces systolic blood pressure (SBP) by (MD -10.9 [95 % CI -17.6 to -4.3], p-value=0.001) with high certainty of evidence. Caucasian whortleberry (MD -16.2 [95 % CI -22.9 to -9.5], p-value<0.0001), Roselle (MD -7.7 [95 % CI -11.9 to -3.5], p-value=0.0003), and Garlic (MD -6.0 [95 % CI -8.8 to -3.2], p-value<0.0001) probably reduce SBP with moderate certainty. No serious adverse events were reported. Conclusion: There is moderate to high certainty that Celery and Caucasian whortleberry were the most effective treatments for reducing blood pressure, among included herbal medicines, in hypertensive and pre-hypertensive patients. Additional long-term, large-sample RCTs are warranted to refine dosing, safety, and sustained effects. Clinicians should interpret results cautiously, given heterogeneity and limited direct evidence for some herbs.