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Am J Hypertens. 2015 Mar;28(3):414-23. doi: 10.1093/ajh/hpu165. Epub 2014 Sep 18.

A systematic review and metaanalysis on the effects of garlic preparations on blood pressure in individuals with hypertension.

Author information

1
Basel Institute for Clinical Epidemiology and Biostatistics, University of Basel, Switzerland;
2
National Institute of Integrative Medicine, Melbourne, Australia;
3
Russian Cardiology Research and Production Complex, Moscow, Russia.
4
Basel Institute for Clinical Epidemiology and Biostatistics, University of Basel, Switzerland; alain.nordmann@usb.ch.

Abstract

BACKGROUND:

Many patients prefer herbal medications to conventional drugs. Limited trial evidence suggests that garlic preparations reduce high blood pressure (BP).

METHODS:

We searched electronic databases through March 2014 to identify all randomized controlled trials that compared a garlic preparation to placebo in hypertensive patients. Trials were required to report BP values at baseline and after a follow-up of at least 4 weeks.

RESULTS:

Nine double-blind trials with 482 individuals fulfilled our inclusion criteria. Included trials were rather small, and the quality of the majority of included trials was moderate. Follow-up ranged from 8 to 26 weeks. All trials reported office BP measurements. Systolic BP and diastolic BP (SBP and DBP) were more effectively reduced in individuals treated with garlic preparations than in individuals treated with placebo. However, heterogeneity was high (weighted mean difference (WMD) for SBP was -9.1 mm Hg; 95% confidence interval (CI), -12.7 to -5.4; P for heterogeneity = 0.0006; and I2 = 71%; WMD for BP was -3.8 mm Hg; 95% CI, -6.7 to -1.0; P for heterogeneity = 0.00001; I2 = 80%). When analyses were restricted to higher-quality trials using intention-to-treat analysis or to trials with concealed treatment allocation and standardized and blinded BP measurement, effect sizes for SBP but not for DBP were lower and heterogeneity disappeared.

CONCLUSIONS:

Although evidence from this review suggests that garlic preparations may lower BP in hypertensive individuals, the evidence is not strong. A well-conducted and powered trial of longer duration is needed to confirm these findings.

KEYWORDS:

blood pressure; garlic; hypertension; metaanalysis.

PMID:
25239480
DOI:
10.1093/ajh/hpu165
[Indexed for MEDLINE]

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