EFFECTS OF BETA-CAROTENE AND ALPHA-TOCOPHEROL ON BLEOMYCIN-INDUCED CHROMOSOMAL DAMAGE

The number of bleomycin-induced chromosomal breaks in cultured periphe ral blood lymphocytes has been proposed as a measure of the sensitivit y of an individual to carcinogens, Although ''mutagen sensitivity'' (c lastogenicity) may be a useful biomarker for the identification of ind ividuals at high risk for DNA damage, there is some uncertainty whethe r the results of this assay can be modified by environmental factors, such as diet, We designed an intervention study to determine whether m icronutrient supplementation with beta-carotene and alpha-tocopherol i nfluenced the mutagenicity score among 22 healthy volunteers, This int ervention study followed a double-blind, randomized, cross-over design , Chromatid breaks ranged from 0.30 to 2.30 per cell and were uncorrel ated with plasma beta-carotene (r = -0.07; P = 0.50) and alpha-tocophe rol (r = -0.01; P = 0.92) levels, after accounting for the time of the measurement, The average number of breaks per cell was similar (P for difference in means = 0.90) among subjects during periods of vitamin supplementation (mean = 0.87 breaks per cell) and placebo (mean = 0.86 breaks per cell), averaged over groups and after adjustment for basel ine breaks, Substantial within-person variation may indicate some impr ecision in the mutagen sensitivity assessment, Our results suggest tha t mutagen sensitivity is not affected by plasma levels of beta-caroten e or alpha-tocopherol. Although mutagen sensitivity does not appear to be modified by changes in plasma levels of two common antioxidant vit amins, it may be useful for the identification of highrisk individuals for participation in large intervention studies with cancer outcomes.