Background : Garlic and sulfur-containing components of garlic have been reported to stimulate nitric oxide synthesis in the endothelium. Nitric oxide production is an important determinant of arterial stiffness.

Objective : To examine the impact of dried garlic powder tablets on arterial stiffness as assessed by measurements of pulse wave velocity (PWV).

Design : Two separate randomized cross-over studies of healthy people (trial I: n=13; trial II: n=9) were conducted. On separate days, participants consumed a high-fat meal (50 g fat) supplemented with garlic powder tablets (8.4 mg alliin), and an identical, but unsupplemented meal. PWV (m s^-1) was measured immediately before and 2-3 h after the test meal.

Results : The unsupplemented fatty meal resulted in a significant 5-6% postprandial increase in PWV in both trials (I: +0.19 m s^-1, p=0.04; II: +0.21 m s^-1, p=0.02). In contrast, the supplemented meal was not associated with any postprandial PWV changes in either trial (I: -0.02 m s^-1, p=0.31; II: 0.00 m s^-1, p=0.95). In pooled analysis (trials I and II), the inhibitory effect of garlic powder on the fatty meal-induced postprandial PWV increase was statistically significant (+0.20 m s^-1 vs -0.01 m s^-1, p=0.01).

Conclusions : The postprandial increase in PWV associated with consumption of a high-fat meal seems to be prevented by dried garlic powder supplementation. Larger, blinded and placebo-controlled trials are needed to confirm the possible antiatherogenic effect.