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June 2008--Dr Reid and others at the University of South Australia conducted a meta analysis on garlic supplementation and blood pressure. Read the entire study (PDF)
Garlic and Blood Pressure Meta Analysis
Ried K, Frank OR, Stocks NP, Fakler P, Sullivan T
Background
Animal studies have suggested that garlic reduces blood pressure, but primary studies in humans and non-systematic reviews have reported mixed results. This paper is an updated systematic review and meta-analysis from 1994 of studies investigating the effect of garlic preparations on blood pressure.
Methods
Medline and Embase databases were searched for studies published between 1955 and October 2007. Randomized controlled trials with true placebo groups, using garlic-only preparations, and reporting mean systolic and/or diastolic blood pressure (SBP/DBP) and standard deviations were included in the meta-analysis. Subgroup meta-analyses by baseline blood pressure (hypertensive/normotensive) were also conducted. Meta-regression analysis was performed to test the associations between blood pressure outcomes and duration of treatment, dosage, and blood pressure at start of treatment.
Results
Eleven of 25 studies included in the systematic review were suitable for meta-analysis. Meta-analysis of all studies showed a mean decrease of 4.6 ± 2.8 mm Hg for SBP in the garlic group compared to placebo (n = 10; p = 0.001), while the mean decrease in the hypertensive subgroup was 8.4 ± 2.8 mm Hg for SBP (n = 4; p < 0.001), and 7.3 ± 1.5 mm Hg for DBP (n = 3; p < 0.001). Regression analysis revealed a significant association between blood pressure at the start of the intervention and the level of blood pressure reduction (SBP: R = 0.057; p = 0.03; DBP: R = -0.315; p = 0.02).
Conclusion
Our meta-analysis suggests that garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension.
Reference
Ried K, Frank OR, Stocks NP, Fakler P, Sullivan T. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008 Jun 16;8:13. Read the entire study (PDF)
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