Effect of vitamins C and E on biomarkers of oxidative stress in nonsmokers

Background—Oxidative stress is elevated in obesity, and may be a major mechanism for obesityrelated diseases. Methods—Nonsmokers (n=396) were randomized to 1000 mg/day vitamin C, 800 IU/day vitamin E, or placebo, for two months. Treatment effect was examined in multiple regression analyses using an intention-to-treat approach. Results—Vitamin C (p=0.001) and vitamin E (p=0.043) reduced plasma F2-isoprostanes. In the overall sample, changes from baseline were +6.8%, −10.6%, and −3.9% for placebo, vitamin C, and vitamin E groups, respectively. However, a significant interaction with baseline F2-isoprostane was found. When baseline F2-isoprostane was > 50 μg/mL, vitamin C reduced F2-isoprostane by 22% (p=0.01). Vitamin E reduced it by 9.8% (p=0.46). Below that cut-point, neither treatment produced further reductions. F2-isoprostane > 50 μg/mL was strongly associated with obesity, and was present in 42% of the sample. Change in malondialdehyde concentration was minimal. Discussion—These findings suggest a role for vitamin C in reducing lipid peroxidation. Future research on effects of vitamins C or E on plasma F2-isoprostane should limit participants to those with baseline levels > 50 μg/mL. Further studies are needed to establish whether treatment with vitamins C or E in persons with concentrations above that cut-point could slow the development of cardiovascular disease.