The effect of increased intakes of polyunsaturated fatty acids and vitaminE on DNA damage in human lymphocytes

The effect of increasing dietary intakes of polyunsaturated fatty acids (PU FAs) and vitamin E on indices of oxidative DNA damage was investigated. Twe nty-one healthy male, nonsmokers aged 28.9 +/- 1.3 years participated in a free-living, split plot/change over trial in which half the volunteers cons umed diets containing 5% PUFA as food energy for 4 wk and, after a 10 wk wa shout period, consumed a 15% PUFA diet for another 4 wk. The other voluntee rs followed an identical protocol, except that they consumed the 15% PUFA d iet first. The diets were provided to volunteers either with or without an additional 80 mg d alpha-tocopherol acetate/day; otherwise total fat, carbo hydrates, protein, and basal vitamin E contents remained unchanged. DNA dam age induced by 200 mu M H2O2 in lymphocytes from volunteers as well as endo genous DNA damage in the form of oxidized pyrimidines, measured by alkaline single-cell gel electrophoresis (the comet assay), significantly decreased after consumption of the 5% PUFA diet (P<0.001 and P=0.01, respectively), but significantly increased after consumption of the 15% PUFA diet when cx- tocopherol levels were in the range of 5-7 mg/day (P=0.008 and P=0.03, resp ectively). These changes were abolished by an additional 80 mg d alpha-toco pherol/day. This study indicates that increasing dietary levels of PUFA to 15% may adversely affect some indices of DNA stability. However, increasing the dietary intake of vitamin E by 80 mg/day ameliorates the damaging effe cts of PUFA.