Although dietary intake and plasma levels of
vitamin C have been inversely associated with
cardiovascular disease, the mechanism through which it may exert its effect has not been fully explained. Since
thrombosis plays an important role in the onset of
cardiovascular disease, we investigated the effect of
vitamin C on measures of hemostasis that have been associated with cardiovascular risk. The effect of
vitamin C on
lipid levels was also evaluated. In a randomized, placebo-controlled, crossover study, we determined the effect of 2 g daily of
vitamin C supplementation on platelet adhesion and aggregation, levels of
tissue plasminogen activator antigen,
plasminogen activator inhibitor,
fibrinogen, plasma viscosity,
von Willebrand factor, and
lipid levels in 18 healthy male volunteers with low normal
vitamin C levels. No striking effects of
vitamin C on the
hemostatic measures were observed, although
tissue plasminogen activator antigen levels were inversely related to
Vitamin C levels.
Von Willebrand factor levels were slightly higher with
vitamin C, although within the normal range. Total
cholesterol levels were 10% lower when subjects were receiving
vitamin C compared to placebo (167+/-7 mg/dL vs. 184+/-7 mg/dL), P=0. 007), although the total
cholesterol/HDL ratio was not significantly different. Higher levels of
tissue plasminogen activator antigen, which in the present study were associated with lower
vitamin C levels, have been shown in prospective studies to convey an increased risk of cardiovascular events. Further studies of the effect of
vitamin C on
hemostatic measures are required in higher risk populations or those with known
cardiovascular disease.