A single high dose of vitamin C counteracts the acute negative effect on microcirculation induced by smoking a cigarette.

Cigarette smoking is associated with marked acute changes in microcirculation including reduced blood flow. We tested the hypothesis that the reduced blood flow velocity is due to the imbalance between prooxidants and antioxidants that occurs as a consequence of smoking and that it can be reduced by an antioxidant. The effect of smoking a single cigarette on nail-fold microcirculation was analyzed in 24 healthy subjects with varying smoking habits. Vital capillary microscopy was used and the blood cell flow velocity in the capillaries was evaluated before and 1-30 min after smoking. Smoking induced a marked decrease in microcirculatory blood flow in 23 of the 24 subjects (40-50% decrease 1-5 min after smoking). This change was reduced by more than 50% in the same subjects after intake of 2 g of vitamin C 2 h before smoking (P < 0.0001 by ANOVA test) with smokers responding similarly to nonsmokers in these experiments. Intake of 1 g of vitamin C had no significant effect on the smoking-induced changes in most of the subjects tested (n = 11). Pretreatment with aspirin had little or no effect on the response to smoking (n = 9). Our results show that treatment with a single high dose of vitamin C can reduce and in some individuals even completely abolish the negative acute effect on microcirculation induced by smoking a single cigarette. This effect of vitamin C is not likely to be mediated by the cyclooxygenase system. Copyright 1999 Academic Press.