title: A prospective study of the intake of vitamins C, E, and A and the risk of breast cancer.
abstract: BACKGROUND
  Although it has been hypothesized that large intakes of the antioxidant vitamins C, E, and A reduce the risk of breast cancer, few prospective data are available.
  
  
  METHODS
  We prospectively studied 89,494 women who were 34 to 59 years old in 1980 and who did not have cancer. Their intakes of vitamins C, E, and A from foods and supplements were assessed at base line and in 1984 with the use of a validated semiquantitative food-frequency questionnaire.
  
  
  RESULTS
  Breast cancer was diagnosed in 1439 women during eight years of follow-up. After multivariate adjustment for known risk factors, the relative risk among women in the highest quintile group for intake of vitamin C as compared with the risk among those in the lowest quintile group was 1.03 (95 percent confidence interval, 0.87 to 1.21); for vitamin E, after vitamin A intake had been controlled for, the relative risk was 0.99 (95 percent confidence interval, 0.83 to 1.19). In contrast, among women in the highest quintile group for intake of total vitamin A the relative risk was 0.84 (95 percent confidence interval, 0.71 to 0.98; P for trend = 0.001). Among women in the lowest quintile group for intake of vitamin A from food, consumption of vitamin A from supplements was associated with a reduced risk (P = 0.03). The significant inverse association of vitamin A intake with the risk of breast cancer was also found on study of data based on the 1984 questionnaire and four years of follow-up.
  
  
  CONCLUSIONS
  Large intakes of vitamin C or E did not protect women in our study from breast cancer. A low intake of vitamin A may increase the risk of this disease; any benefit of vitamin A supplements may be limited to women with diets low in vitamin A.
authors.affiliation: Channing Laboratory, Department of Medicine, Harvard Medical School, Boston, MA 02115.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: J E
authors.initials: JE
authors.lastname: Manson
authors.forename: G A
authors.initials: GA
authors.lastname: Colditz
authors.forename: M J
authors.initials: MJ
authors.lastname: Stampfer
authors.forename: B
authors.initials: B
authors.lastname: Rosner
authors.forename: C H
authors.initials: CH
authors.lastname: Hennekens
authors.forename: F E
authors.initials: FE
authors.lastname: Speizer
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
mesh_terms: D000328:Adult; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D004032:Diet; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014801:Vitamin A / Q000008:administration & dosage*; D014810:Vitamin E / Q000008:administration & dosage*
chemical_list: D014801:Vitamin A; D014810:Vitamin E; D001205:Ascorbic Acid