title: Dietary Fiber Intake in Young Adults and Breast Cancer Risk.
abstract: OBJECTIVE
  We evaluated fiber intake during adolescence and early adulthood in relation to breast cancer (BC) risk in the Nurses' Health Study II.
  
  
  METHODS
  Among 90,534 premenopausal women who completed a dietary questionnaire in 1991, we documented 2833 invasive BC cases during 20 years of follow-up. In 1998, 44,263 of these women also completed a questionnaire about their diet during high school; among these women, we documented 1118 cases of BC by end of follow-up. Multivariable-adjusted Cox proportional hazards regression was used to model relative risks (RRs) and 95% confidence intervals (CIs) for BC across categories of dietary fiber.
  
  
  RESULTS
  Among all women, early adulthood total dietary fiber intake was associated with significantly lower BC risk (RR for highest versus lowest quintile 0.81; 95% CI 0.72-0.91; Ptrend = .002). Higher intakes of soluble fiber (RR for highest versus lowest quintile 0.86; 95% CI 0.77-0.97; Ptrend = .02) and insoluble fiber (RR for highest versus lowest quintile 0.80; 95% CI 0.71-0.90; Ptrend < .001) were each associated with lower BC risk. Total dietary fiber intake in adolescence was also associated with lower BC risk (RR for highest versus lowest quintile 0.84; 95% CI 0.70-1.01; Ptrend = .04). For the average of fiber intake during adolescence and early adult life, the RR comparing highest with lowest quintiles was 0.75 (95% CI 0.62-0.91, Ptrend = .004).
  
  
  CONCLUSIONS
  Our findings support the hypothesis that higher fiber intakes reduce BC risk and suggest that intake during adolescence and early adulthood may be particularly important.
authors.affiliation: Departments of Nutrition, mfarvid@hsph.harvard.edu.
authors.forename: Maryam S
authors.initials: MS
authors.lastname: Farvid
authors.affiliation: Epidemiology, and Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts;
authors.forename: A Heather
authors.initials: AH
authors.lastname: Eliassen
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Dermatology, The Warren Alpert Medical School of Brown University, Providence, Rhode Island; and.
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Cho
authors.affiliation: Epidemiology, and Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts;
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Liao
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Wendy Y
authors.initials: WY
authors.lastname: Chen
authors.affiliation: Departments of Nutrition, Epidemiology, and Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts;
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
mesh_terms: D000293:Adolescent; D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology*; D004043:Dietary Fiber / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D009726:Nurses; D017698:Postmenopause; D017697:Premenopause; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult