Vitamin C improves endothelial dysfunction in renal allograft recipients

Abstract

Background: Endothelial function is impaired in renal allograft recipients but the effects of antioxidant vitamin therapy on endothelial function in such patients is unknown.

Methods: Thirteen renal allograft recipients were randomized to vitamin C or placebo in a double blind cross-over study design. Flow-mediated endothelium-dependent dilation and glyceryltrinitrate-induced endothelium-independent dilation of the brachial artery were assessed before and 2 h after oral administration of 2 g vitamin C or placebo.

Results: Plasma vitamin C levels increased from 33.5+/-17.0 micromol/l to 98.8+/-60.2 micromol/l after treatment (P=0.0001). Endothelium-dependent dilation improved (from 1.6+/-2.6 to 4.5+/-2.5%) after vitamin C administration but was unchanged after placebo (1.9+/-1.5 to 1.8+/-2.5%; P=0.003 for vitamin C vs placebo). There was no significant change in endothelium-independent dilation in response to vitamin C. Vitamin C was also associated with a significant increase in the lag time in dilute serum oxidation (P=0.001).

Conclusions: Vitamin C acutely improves flow-mediated, endothelium-dependent dilation and increases the resistance of lipoproteins in dilute serum to oxidation in renal transplant recipients.