title: Steady-state serum concentration of alpha tocopherol not altered by supplementation with oral beta carotene. The Polyp Prevention Study 1 Group.
abstract: BACKGROUND
  The antioxidants beta carotene and vitamin E may play a role in cancer prevention. However, some studies have suggested that oral supplements of beta carotene may cause a decrease in serum levels of alpha tocopherol (vitamin E).
  
  
  OBJECTIVE
  We conducted this study to determine if beta carotene supplements affect serum levels of vitamin E and vice versa.
  
  
  METHODS
  Five hundred five patients in a clinical trial of antioxidant vitamins, used to prevent recurrences of colonic polyps, received either a placebo, 25 mg of beta carotene per day, 1 g ascorbic acid plus 400 mg alpha tocopherol per day, or all three agents combined. Serum levels of beta carotene and vitamin E were measured before and after 9 months of supplementation, using high-performance liquid chromatography.
  
  
  RESULTS
  Vitamin E levels changed very little among the groups receiving placebo or beta carotene and went up substantially and equally in the groups receiving vitamin E plus ascorbic acid or all three agents together. Conversely, beta carotene levels changed very little for the groups receiving placebo or ascorbic acid plus vitamin E but went up substantially and equally for the groups receiving beta carotene alone or all three agents.
  
  
  CONCLUSIONS
  We conclude that oral supplementation with beta carotene for 9 months does not alter serum concentration of vitamin E and that supplementation with vitamin E plus ascorbic acid does not alter serum beta carotene levels.
authors.affiliation: Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756.
authors.forename: D W
authors.initials: DW
authors.lastname: Nierenberg
authors.forename: T A
authors.initials: TA
authors.lastname: Stukel
authors.forename: L A
authors.initials: LA
authors.lastname: Mott
authors.forename: E R
authors.initials: ER
authors.lastname: Greenberg
mesh_terms: D000284:Administration, Oral; D000368:Aged; D001205:Ascorbic Acid / Q000627:therapeutic use; D002338:Carotenoids / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use*; D003111:Colonic Polyps / Q000097:blood / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014810:Vitamin E / Q000097:blood* / Q000627:therapeutic use*
chemical_list: D014810:Vitamin E; D002338:Carotenoids; D001205:Ascorbic Acid