Effect of garlic on blood pressure: a systematic review and meta-analysis

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#blood-pressure #garlic #humans #hypertension #phytotherapy

Effect of garlic on blood pressure: a systematic review and meta-analysis

Ried et al., 2008 | BMC Cardiovasc Disord | Meta Analysis

Citation

Ried Karin, Frank Oliver R, ... Sullivan Thomas. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008-Jun-16;8:13. doi:10.1186/1471-2261-8-13

Abstract

BACKGROUND: Non-pharmacological treatment options for hypertension have the potential to reduce the risk of cardiovascular disease at a population level. Animal studies have suggested that garlic reduces blood pressure, but primary studies in humans and non-systematic reviews have reported mixed results. With interest in complementary medicine for hypertension increasing, it is timely to update a systematic review and meta-analysis from 1994 of studies investigating the effect of garlic preparations on blood pressure. METHODS: We searched the Medline and Embase databases for studies published between 1955 and October 2007. Randomised 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. We also conducted subgroup meta-analysis by baseline blood pressure (hypertensive/normotensive), for the first time. 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.

Key Findings

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 th

Outcomes Measured

  • blood pressure
  • systolic blood pressure
  • diastolic blood pressure

Population

Field Value
Population hypertension
Sample Size 10
Age Range See abstract
Condition hypertension

MeSH Terms

  • Blood Pressure
  • Garlic
  • Humans
  • Hypertension
  • Phytotherapy
  • Plant Preparations

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Research Support, Non-U.S. Gov't, Systematic Review
  • Vertical: garlic-cardiovascular

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09