A clinical trial to evaluate the effect of vitamin C supplementation on in vitro mutagen sensitivity

Mutagen sensitivity, as measured by an in vitro assay, has been described as a risk factor for the development of several tobacco-related epithelial cancers. In vitro studies have indicated that sensitivity to the clastogenic effects of bleomycin on chromosomes was reduced with the introduction of ascorbic acid in a dose-dependent relationship. We report the results of a randomized clinical trial to determine whether increasing levels of oral ascorbic acid could reduce the levels of mutagen sensitivity. For this study, we recruited 228 healthy smokers from 21 centers around the country through the Clinical Community Oncology Program. Each individual was randomly assigned to one of four daily regimens: placebo, 1 g of ascorbic acid, 2 g of ascorhic acid, or 4 g of ascorbic acid. Treatments were administered for 16 weeks. Assessment of mutagen sensitivity was made at baseline and at weeks 4, 16, and 20 (4 weeks after cessation of treatment). Serum ascorbic acid levels were measured at baseline and at weeks 4 and 16. Demographic and risk factor data were collected at baseline and at each measurement point. Analyses measured the differences of mutagen sensitivity levels across the four treatment arms, as well as investigating the correlation between serum ascorbic acid level and mutagen sensitivity levels in individuals. We did not find a dose-response relationship between ascorbic acid intake and mutagen sensitivity. Additionally, we did not find an association between serum ascorbic acid levels and mutagen sensitivity.