Lack of effect of acute oral ingestion of vitamin C on oxidative stress, arterial stiffness or blood pressure in healthy subjects

Vitamin C is a potent antioxidant in vitro and has been reported to act as a vasodilator, possibly by increasing nitric oxide bioavailability. This study examined the antioxidant and vascular effects of a single large oral dose of vitamin C in 26 healthy human volunteers. Haemodynamic and oxidative DNA and lipid damage markers were measured for 8 h following an oral dose of 2 g vitamin C or placebo. Vitamin C had no effect on vasodilation (measured by augmentation index (mean change=0.04%, 90% CI=− 2.20% to 2.28%) or forearm blood flow (−0.19%/min (−0.68, 0.30)), in comparison to placebo) or on several markers of oxidative stress including DNA base oxidation products in blood cells, 8-hydroxy-2'-deoxyguanosine (8O HdG) in urine (0.068 (−0.009, 0.144)) or urinary or plasma total F2-isoprostanes (−0.005 ng/ml (−0.021, 0.010), −0.153 ng/mg (−0.319, 0.014), respectively).