A single blueberry (Vaccinium corymbosum) portion does not affect markers of antioxidant defence and oxidative stress in healthy volunteers following cigarette smoking

We previously reported that a portion of blueberries reversed endothelial dysfunction induced by acute cigarette smoking. Since smoking-induced endothelial dysfunction is associated with a condition of oxidative stress, we evaluated whether the observed effect was mediated by modulation of markers of oxidative stress and antioxidant defence. Fourteen out of 16 male healthy smokers previously enrolled, participated in a three-armed randomized controlled study with the following experimental conditions: smoking treatment (one cigarette); blueberry treatment (300g of blueberries) + smoking (one cigarette); control treatment (300ml of water with sugar) + smoking (one cigarette). The cigarette was smoked 100min after blueberry/control/water consumption. Each treatment was separated by 1 week of washout period. Plasma vitamin (C, B12 and folate) and aminothiol concentrations, endogenous [formamidopyrimidine-DNA glycosylase (FPG)-sensitive sites] and oxidatively induced DNA damage (resistance to H2O2-induced DNA damage) in peripheral blood mononuclear cells (PBMCs) were measured at baseline and 20, 60, 90, 120min and 24h after smoking. On the whole, analysis of variance did not show a significant effect of treatment on the modulation of markers of oxidative stress and antioxidant defence but revealed an effect of time for plasma concentrations of vitamin C (P = 0.003), B12 (P < 0.001), folate (P < 0.001), total cysteine (P = 0.007) and cysteine-glycine (P = 0.010) that increased following the three treatments after smoking. No significant effect of treatment was observed for the levels of FPG-sensitive sites (P > 0.05) and H2O2-induced DNA damage (P > 0.05) in PBMCs. In conclusion, the consumption of a single blueberry portion failed to modulate markers of oxidative stress and antioxidant defence investigated in our experimental conditions. Further studies are necessary to elucidate this finding and help clarifying the mechanisms of protection of blueberries against smoking-induced endothelial dysfunction.