Ten RCTs (n=401) were included in the review: two crossover RCTs and eight parallel RCTs. Three RCTs (n=139) evaluated hypertensive participants and seven RCTs (n=262) evaluated normotensive participants.
In patients with elevated baseline systolic blood pressure (hypertensive), garlic reduced systolic blood pressure by -16.3mmHg (95% CI -26.45 to -6.22) and diastolic blood pressure by -9.3mmHg (95% CI -13.30 to -5.25; three studies) in comparison with placebo.
In participants without elevated baseline systolic blood pressure (normotensive), there were no statistically significant differences between garlic and placebo for systolic blood pressure (WMD -0.5mmHg, 95% CI -3.11 to 2.05) or diastolic blood pressure (WMD -0.89, 95% CI -2.69 to 0.92).
Heterogeneity did not reach statistical significance (data not reported). There was no evidence of publication bias for studies of normotensive participants (data not reported); the number of studies was too few to allow analysis of publication bias for studies of hypertensive participants.