title: The influence of high doses of vitamin C and zinc on oxidative DNA damage.
abstract: BACKGROUND
  The influence of interactions between reactive oxygen species (ROS) and dietary antioxidants and their influence on cancer is not clear. It is believed that this effect is mediated by decreased oxidative damage to DNA. The aim of this study was to further investigate the in vitro DNA protective or damaging effects of dietary antioxidants using the single cell gel electrophoresis (Comet) assay.
  
  
  METHODS
  Stimulated and unstimulated lymphocytes of 10 individuals were cultured with and without different concentrations of vitamins C and zinc and damaged with H2O2.
  
  
  RESULTS
  DNA damage measured by Olive tail moment in the Comet assay showed a non-significant trend to reduce DNA strand breaks at low vitamin and trace element concentrations. At higher vitamin C and zinc doses, DNA damage was significantly increased.
  
  
  CONCLUSIONS
  The in vitro data of the present study suggest that high dosage intake of vitamin C and zinc may cause more harm than benefit. There is good evidence that health-related effects of dietary antioxidants strongly depend on individual genetic susceptibilities and health status.
authors.affiliation: Clinical Experimental Oncology, ENT Department, Ludwig-Maximilians-University, Munich, D-80336 München, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Harréus
authors.forename: Philipp
authors.initials: P
authors.lastname: Baumeister
authors.forename: Sabina
authors.initials: S
authors.lastname: Zieger
authors.forename: Christoph
authors.initials: C
authors.lastname: Matthias
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D020552:Comet Assay; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004249:DNA Damage; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress; D015032:Zinc / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D004247:DNA; D006861:Hydrogen Peroxide; D015032:Zinc; D001205:Ascorbic Acid