Oral vitamin c reduces arterial stiffness and platelet aggregation in humans

Atherosclerosis is associated with stiffening of conduit arteries and incre ased platelet activation, partly as a result of reduced bioavailability of nitric oxide (NO), a mediator that normally has a variety of protective eff ects on blood vessels and platelets. Increased levels of oxygen free radica ls are a feature of atherosclerosis that contributes to reduced NO bioavail ability and might lead to increased arterial stiffness and platelet activat ion. Vitamin C is a dietary antioxidant that inactivates oxygen free radica ls. This placebo-controlled, double-blind, randomized study was designed to establish whether acute oral administration of vitamin C (2 g), would redu ce arterial stiffness and in vitro platelet aggregation in healthy male vol unteers. Plasma vitamin C concentrations increased from 42 +/- 8 to 104 +/- 8 mu M at 6 h after oral administration, and were associated with a signif icant reduction in augmentation index, a measure of arterial stiffness (by 9.6 +/- 3.08; p = 0.016), and ADP-induced platelet aggregation (by 35 +/- 1 3%; p = 0.046). There was no change in these parameters after placebo. Vita min C, therefore, appears to have beneficial effects, even in healthy subje cts. The mechanism responsible is likely to involve protection of NO from i nactivation by oxygen free radicals, but this requires confirmation. If sim ilar effects are observed in patients with atherosclerosis or risk factors, vitamin C supplementation might prove an effective therapy in cardiovascul ar disease.