Hibiscus sabdariffa L. is a tropical wild plant rich in organic acids, polyphenols, anthocyanins, polysaccharides, and volatile constituents that are beneficial for the cardiovascular system. Hibiscus sabdariffa beverages are commonly consumed to treat arterial hypertension, yet the evidence from randomized controlled trials (RCTs) has not been fully conclusive. Therefore, we aimed to assess the potential antihypertensive effects of H. sabdariffa through systematic review of literature and meta-analysis of available RCTs.
The search included PUBMED, Cochrane Library, Scopus, and EMBASE (up to July 2014) to identify RCTs investigating the efficacy of H. sabdariffa supplementation on SBP and DBP values. Two independent reviewers extracted data on the study characteristics, methods, and outcomes. Quantitative data synthesis and meta-regression were performed using a fixed-effect model, and sensitivity analysis using leave-one-out method. Five RCTs (comprising seven treatment arms) were selected for the meta-analysis. In total, 390 participants were randomized, of whom 225 were allocated to the H. sabdariffa supplementation group and 165 to the control group in the selected studies.
Fixed-effect meta-regression indicated a significant effect of H. sabdariffa supplementation in lowering both SBP (weighed mean difference −7.58 mmHg, 95% confidence interval −9.69 to −5.46, P < 0.00001) and DBP (weighed mean difference −3.53 mmHg, 95% confidence interval −5.16 to −1.89, P < 0.0001). These effects were inversely associated with baseline BP values, and were robust in sensitivity analyses.
This meta-analysis of RCTs showed a significant effect of H. sabdariffa in lowering both SBP and DBP. Further well designed trials are necessary to validate these results.
aDepartment of Functional Sciences, Discipline of Pathophysiology, ‘Victor Babes’ University of Medicine and Pharmacy, Timisoara, Romania
bBiotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
cMetabolic Research Centre, Royal Perth Hospital, School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
dDepartment of Functional Sciences, Discipline of Public Health
eFaculty of Pharmacy, Discipline of Pharmaceutical Chemistry ‘Victor Babes’ University of Medicine and Pharmacy, Timisoara, Romania
fDepartment of Hypertension, Chair of Nephrology and Hypertension, Medical University of Lodz, Poland
*Drs Corina Serban and Amirhossein Sahebkar contributed equally to the writing of this article.
Correspondence to Professor Maciej Banach, MD, PhD, FNLA, FAHA, FESC, FASA, Head, Department of Hypertension, WAM University Hospital in Lodz, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland. Tel: +48 42 639 37 71; fax: +48 42 639 37 71; e-mail: email@example.com
Abbreviations: ACE, angiotensin-converting enzyme; CI, confidence interval; CMA, comprehensive meta-analysis; NOS, nitric oxide synthase; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analysis; RCTs, randomized controlled trials; WMD, weighed mean difference
Received 27 August, 2014
Revised 4 March, 2015
Accepted 4 March, 2015