title: Dietary vitamin D and calcium intake and mammographic density in postmenopausal women.
abstract: OBJECTIVE
  Dietary intake of vitamin D and calcium may be related to risk of breast cancer, possibly by affecting mammographic density. However, the few studies that have evaluated the association between these nutrients and mammographic density in postmenopausal women have had inconsistent results.
  
  
  METHODS
  We conducted a cross-sectional analysis in 808 participants of the Mammogram Density Ancillary Study of the Women's Health Initiative. Mammographic percent density was measured using baseline mammograms taken before randomization of participants in the intervention trials. Vitamin D and calcium intake was assessed with a validated food frequency questionnaire and an inventory of current supplement use, both completed at baseline.
  
  
  RESULTS
  After adjustment for age, body mass index, regional solar irradiance, and other factors, we did not find a relationship between vitamin D or calcium intake and mammographic density. Mean mammographic percent densities in women reporting total vitamin D intakes of less than 100, 100 to 199, 200 to 399, 400 to 599, and 600 or greater IU/day were 5.8%, 10.4%, 6.2%, 3.8%, and 5.1%, respectively (P trend = 0.67). Results in women reporting a total calcium intake of less than 500, 500 to 749, 750 to 999, 1,000 to 1,199, and 1,200 or greater mg/day were 7.3%, 4.9%, 7.3%, 6.9%, and 7.11%, respectively (P trend = 0.51). We did not observe any effect modification by overall level of mammographic density or solar irradiance, but supplemental vitamin D use was associated with lower density in younger women (P interaction = 0.009).
  
  
  CONCLUSIONS
  These findings do not support a relationship between dietary vitamin D or calcium intake and mammographic density in postmenopausal women. Additional studies should explore these associations in women of different ages and in relation to serum vitamin D levels.
authors.affiliation: University of Massachusetts, Amherst, MA 01003-9304, USA. ebertone@schoolph.umass.edu
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Bertone-Johnson
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Aragaki
authors.forename: Rulla M
authors.initials: RM
authors.lastname: Tamimi
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Rexrode
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Rohan
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Peck
authors.forename: Etta D
authors.initials: ED
authors.lastname: Pisano
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Martin
authors.forename: Gloria
authors.initials: G
authors.lastname: Sarto
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
mesh_terms: D000368:Aged; D001940:Breast / Q000033:anatomy & histology* / Q000187:drug effects*; D001943:Breast Neoplasms / Q000453:epidemiology*; D002136:Calcium, Dietary / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008327:Mammography; D008875:Middle Aged; D015999:Multivariate Analysis; D017698:Postmenopause; D057566:Self Report; D014807:Vitamin D / Q000494:pharmacology*
chemical_list: D002136:Calcium, Dietary; D014807:Vitamin D