The effect of garlic on the lowering of blood pressure in the patients with hypertension: an updated meta-analysis and trial sequential analysis.

Background: Garlic extracts have been demonstrated to be effective supplements for reducing blood pressure in hypertensive subjects. However, contradictory observations on the efficacy of garlic extracts have been reported in different studies.

Objectives: To explore the efficacy of garlic, this study aimed to perform a meta-analysis of previously published controlled placebo trials and drew firm conclusions.

Methods: We searched online databases, including Scopus, PubMed, and Science Direct, to obtain relevant articles on the role of garlic in reducing blood pressure in patients with hypertension. The literature search, data extraction, and analysis were performed independently by two researchers. Comprehensive Meta-Analysis Software v4 was used for all the analyses.

Results: Twelve reports, comprising 405 patients treated with garlic derivatives and 333 receiving placebo, were included in this investigation. The results of the meta-analysis revealed a significant decrease in systolic blood pressure (mean difference: -8.121, 95% confidence interval [CI]: -10.95 to -5.28, P < 0.0001) and diastolic blood pressure (mean difference: -4.256, 95% CI: -5.99 to -2.52, P < 0.0001) in subjects treated with garlic extracts compared to those treated with placebo. Interestingly, trial sequential analysis also supports the observations of the meta-analysis and indicates that a sufficient number of trials have already been performed to reach a consensus conclusion, and further trials are not required. In addition, the GRADEing of evidence also supports the robustness of the observations.

Conclusions: Garlic extracts significantly lower blood pressure and may be prescribed by clinicians for patients with hypertension.