Garlic lowers blood pressure in hypertensive subjects, improves arterial stiffness and gut microbiota: A review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 32010325 · doi:10.3892/etm.2019.8374
What was done
Authors searched electronic databases (PubMed and Google Scholar) from 1955 to December 2018 for randomized controlled trials (RCTs) evaluating the effects of garlic on blood pressure in hypertensive individuals. A meta-analysis of blood pressure outcomes was conducted, alongside a narrative review of clinical trials investigating Kyolic aged garlic extract effects on arterial stiffness, gut microbiota, and the role of vitamin B12 status.
What was found
A meta-analysis of 12 RCTs comprising 553 hypertensive participants showed that garlic supplements reduced systolic blood pressure by an average of 8.3 ± 1.9 mmHg. Diastolic blood pressure was reduced by 5.5 ± 1.9 mmHg based on 8 trials (n = 374 subjects). The authors reported this reduction is associated with an estimated 16–40% decrease in cardiovascular event risk. In narrative review findings, Kyolic aged garlic extract lowered central blood pressure, pulse pressure, pulse wave velocity, and arterial stiffness, while increasing gut microbial richness, diversity, and abundance of Lactobacillus and Clostridia species after 3 months.
Why it matters
Standardized garlic supplementation produces clinically meaningful blood pressure reductions comparable to some standard antihypertensive medications, supporting its role as a potential standalone or adjunctive therapy for hypertension.
Limits
The total pooled sample size across 12 trials is relatively small (553 participants, averaging ~46 participants per trial). The abstract does not report confidence intervals, between-study heterogeneity (I²), adverse events, or details on specific garlic preparations and doses used across trials. Cardiovascular event reductions are calculated estimates rather than observed clinical endpoints, and the gut microbiota and arterial stiffness outcomes were reviewed narratively rather than meta-analyzed.
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