Background: Hypertension affects 30% of adults worldwide. Garlic supplements have
shown promise in the treatment of uncontrolled hypertension, and the mechanism of action is
biologically plausible. Our trial is the first to assess the effect of aged garlic extract on central
blood pressure and arterial stiffness, regarded as important risk factors for cardiovascular
Subjects and methods: A total of 88 general practice patients and community members with
uncontrolled hypertension completed a double-blind randomized placebo-controlled trial of
12 weeks investigating the effect of daily intake of aged garlic extract (1.2 g containing 1.2 mg
S-allylcysteine) or placebo on blood pressure, and secondary outcome measures of centralhemodynamics and other cardiovascular markers, including cholesterol, homocysteine, platelet function, and inflammatory markers.
Results: Mean blood pressure was significantly reduced by 5.0±2.1 mmHg (P=0.016) systolic,
and in responders by 11.5±1.9 mmHg systolic and 6.3±1.1 mmHg diastolic compared to placebo
(P,0.001). Central hemodynamic-measures tended to improve in the garlic group more than
in the placebo group, including central blood pressure, central pulse pressure, mean arterial
pressure, augmentation pressure, pulse-wave velocity, and arterial stiffness. While changes in
other cardiovascular markers did not reach significance due to small numbers in subgroups
with elevated levels, trends in beneficial effects of garlic on the inflammatory markers TNFα,
total cholesterol, low-density lipid cholesterol, and apolipoproteins were observed. Aged garlic
extract was highly tolerable and acceptable, and did not increase the risk of bleeding in patients
on blood-thinning medication.
Conclusion: Our trial suggests that aged garlic extract is effective in reducing peripheral and
central blood pressure in a large proportion of patients with uncontrolled hypertension, and has
the potential to improve arterial stiffness, inflammation, and other cardiovascular markers in
patients with elevated levels. Aged garlic extract was highly tolerable with a high safety profile
as a stand-alone or adjunctive antihypertensive treatment.