The effects of acute garlic supplementation on the fibrinolytic and vasoreactive response to exercise

BACKGROUND The purpose of this project was to examine the effects of acute garlic supplementation on fibrinolysis and vasoreactivity both at rest and following maximal exercise. METHODS Eighteen healthy trained males (20.9 ± 2.2 years, 178 ± 7.7 cm, 75.5 ± 9.6 kg, VO2max = 59.8 ± 6.7 ml • kg(-1) • min(-1)) performed a graded treadmill test to volitional exhaustion. Blood samples were taken at rest, within two minutes post-exercise, and one hour post-exercise. Eleven of the subjects also had a brachial vasoreactivity test performed immediately after the blood sample to assess flow-mediated dilation (FMD) of the brachial artery. Participants were randomly assigned to ingest either 900 mg of powdered garlic or a placebo three hours before the exercise session. The supplement was distributed in a double-blind, crossover fashion. Participants repeated the protocol with the other treatment after a 14-day washout period. Paired t-tests were used to compare VO2max between the two trials. A two-factor (treatment and time) repeated measures analysis of variance (ANOVA) was used to assess changes in FMD, tPA activity, tPA antigen, and PAI-1 activity. A priori statistical significance was set at P <0.05. RESULTS VO2max was greater for the garlic treatment trial vs. placebo (Placebo = 59.8 ± 6.7 ml • kg(-1) • min(-1); Garlic = 61.4 ± 6.6 ml • kg(-1) • min(-1)). There was no main effect for treatment and no treatment x time interaction for FMD or any fibrinolytic variables examined. CONCLUSION Acute garlic supplementation does not alter vasoreactivity, fibrinolytic potential or the fibrinolytic response to exercise in young healthy trained males. Acute garlic supplementation does, however, cause a small but statistically significant increase in VO2max. It remains unclear if this increase in VO2max is of functional importance.