Whole and refined grain intake and risk of incident postmenopausal breast cancer (United States)

Kristin K. Nicodemus, David R. Jacobs, Aaron R. Folsom

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


Objective: To assess the relation between whole and refined grain intake and risk of incident postmenopausal breast cancer. Findings from case-control studies of whole and refined grain intake and risk of postmenopausal breast cancer have been inconclusive. Methods: The Iowa Women's Health Study is a prospective cohort study of women initially 55-69 years old that relates diet and other lifestyle factors to cancer risk. After exclusions a total of 29,119 menopausal women who answered a 1986 baseline and a 1989 follow-up questionnaire were followed for 9 years for incident breast cancer. Results: Compared to women who at baseline rarely ate whole grain foods, women who habitually ate whole grain had a healthier lifestyle, including a higher likelihood of prior screening mammography. The multivariate-adjusted risk of incident breast cancer was 20% higher in women in the highest quintile of whole grain intake, compared to women in the lowest quintile of whole grain intake (95% confidence interval 0.95-1.5; p-value for trend = 0.03). No increase in breast cancer risk was found in women who had not undergone screening mammography before 1989; the apparent increase in risk was therefore likely due to increased use of screening mammography. Refined grain intake was not associated with breast cancer risk. Conclusion: Consistent with inverse but not statistically significant associations between whole grain intake and breast cancer in case-control studies, both whole and refined grain intakes are unrelated to risk of postmenopausal breast cancer in these Iowa women.

Original languageEnglish (US)
Pages (from-to)917-925
Number of pages9
JournalCancer Causes and Control
Issue number10
StatePublished - 2001

Bibliographical note

Funding Information:
This research was supported by National Cancer Institute Grant R01 CA39742.


  • Breast neoplasms
  • Diet
  • Iowa Women's Health Study
  • Postmenopausal women
  • Refined grains
  • Whole grains


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