Can vitamin C supplementation reverse the effects of exercise training in polluted air on oxidative stress markers? A randomized controlled trial

BACKGROUND: Air pollution and long-term aerobic exercise are diversely associated with cardiovascular disease (CVD) and mortality. However, the simultaneous effect of exercise in polluted air and vitamin C on oxidative stress markers is less clear. In this study, the effect of these variables on oxidative stress markers was investigated in rats. METHODS: The study was conducted on 50 male rats. The rats were divided into 5 groups consisting of exercise, exercise with vitamin C, exercise in polluted air, exercise in polluted air with vitamin C, and control group. Animals in the exercise groups exercised on a treadmill for 12 weeks, 5 days/week, 30 minutes/day, at 50-70% of the maximum speed. Animals in the vitamin C groups received 20 mg/kg/day vitamin C orally. After 12 weeks of intervention, 2.5 ml of blood was taken from the rats’ apex. Malondialdehyde (MDA) and oxidized low-density lipoprotein (OxLDL) levels were measured using NavandSalamat’s Nalondi and Eastbiopharm’s OxLDL ELISA kits, respectively. Two-way analysis of variance (ANOVA) was used for data analysis in SPSS software. RESULTS: There were significant differences in MDA and OxLDL levels between all groups after 12 weeks of intervention (P < 0.050). The levels of MDA and OxLDL were significantly higher in the ExPo group compared to the Ex+VitC groups (P < 0.050). However, no significant difference was observed in MDA and OxLDL levels between the vitamin C groups (P > 0.050). CONCLUSION: These findings demonstrate the oxidative stress effects of air pollution, systemically and in the respiratory tract. Moreover, polluted air significantly increased OxLDL levels in both exercise in polluted air groups. Although, vitamin C slightly decreased MDA and OxLDL levels in the ExPo groups, the difference was not significant. Different vitamin C doses could have diverse and maybe significant results.