The effect of vitamin C supplementation on coagulability and lipid levels in healthy male subjects

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 im portant role in the onset of cardiovascular disease, we investigated the ef fect of vitamin C on measures of hemostasis that have been associated with cardiovascular risk. The effect of vitamin C on lipid levels was also evalu ated. In a randomized, placebo-controlled, crossover study, we determined t he effect of 2 g daily of vitamin C supplementation on platelet adhesion an d aggregation, levels of tissue plasminogen activator antigen, plasminogen activator inhibitor, fibrinogen, plasma viscosity, von Willebrand factor, a nd lipid levels in 18 healthy male volunteers with low normal vitamin C lev els. No striking effects of vitamin C on the hemostatic measures were obser ved, although tissue plasminogen activator antigen levels were inversely re lated to Vitamin C levels (R=-0.33, P=0.04). Von Willebrand factor levels w ere slightly higher with vitamin C, although within the normal range. Total cholesterol levels were 10% lower when subjects were receiving vitamin C c ompared to placebo (167+/-7 mg/dL vs. 184+/-7 mg/dL), P=0.007), although th e total cholesterol/HDL ratio was not significantly different. Higher level s of tissue plasminogen activator antigen, which in the present study were associated with lower vitamin C levels, have been shown in prospective stud ies to convey an increased risk of cardiovascular events. Further studies o f the effect of vitamin C on hemostatic measures are required in higher ris k populations or those with known cardiovascular disease. (C) 2000 Elsevier Science Ltd. All rights reserved.