title: Habitual intake of flavonoid subclasses and risk of colorectal cancer in 2 large prospective cohorts.
abstract: BACKGROUND
  Flavonoids inhibit the growth of colon cancer cells in vitro. In a secondary analysis of a randomized controlled trial, the Polyp Prevention Trial, a higher intake of one subclass, flavonols, was statistically significantly associated with a reduced risk of recurrent advanced adenoma. Most previous prospective studies on colorectal cancer evaluated only a limited number of flavonoid subclasses and intake ranges, yielding inconsistent results.
  
  
  OBJECTIVE
  In this study, we examined whether higher habitual dietary intakes of flavonoid subclasses (flavonols, flavones, flavanones, flavan-3-ols, and anthocyanins) were associated with a lower risk of colorectal cancer.
  
  
  METHODS
  Using data from validated food-frequency questionnaires administered every 4 y and an updated flavonoid food composition database, we calculated flavonoid intakes for 42,478 male participants from the Health Professionals Follow-Up Study and for 76,364 female participants from the Nurses' Health Study.
  
  
  RESULTS
  During up to 26 y of follow-up, 2519 colorectal cancer cases (1061 in men, 1458 in women) were documented. Intakes of flavonoid subclasses were not associated with risk of colorectal cancer in either cohort. Pooled multivariable adjusted RRs (95% CIs) comparing the highest with the lowest quintiles were 1.04 (0.91, 1.18) for flavonols, 1.01 (0.89, 1.15) for flavones, 0.96 (0.84, 1.10) for flavanones, 1.07 (0.95, 1.21) for flavan-3-ols, and 0.98 (0.81, 1.19) for anthocyanins (all P values for heterogeneity by sex >0.19). In subsite analyses, flavonoid intake was also not associated with colon or rectal cancer risk.
  
  
  CONCLUSIONS
  Our findings do not support the hypothesis that a higher habitual intake of any flavonoid subclass decreases the risk of colorectal cancer.
authors.affiliation: Molecular Epidemiology Research Group, Max Delbrück Center for Molecular Medicine, Berlin, Germany; Department of Nutrition and katharina.nimptsch@mdc-berlin.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Nimptsch
authors.affiliation: Channing Division of Network Medicine, Department of Medicine and.
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, United Kingdom;
authors.forename: Aedín
authors.initials: A
authors.lastname: Cassidy
authors.affiliation: Department of Nutrition and.
authors.forename: Mingyang
authors.initials: M
authors.lastname: Song
authors.affiliation: Department of Nutrition and Channing Division of Network Medicine, Department of Medicine and.
authors.forename: Éilis J
authors.initials: ÉJ
authors.lastname: O'Reilly
authors.affiliation: Safety Statistics and Observational Research Analytics, Quantitative Sciences, Takeda Development Center Americas Inc., Deerfield, IL;
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Lin
authors.affiliation: Molecular Epidemiology Research Group, Max Delbrück Center for Molecular Medicine, Berlin, Germany;
authors.forename: Tobias
authors.initials: T
authors.lastname: Pischon
authors.affiliation: Department of Nutrition and Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA; Channing Division of Network Medicine, Department of Medicine and.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Rimm
authors.affiliation: Department of Nutrition and Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA; Channing Division of Network Medicine, Department of Medicine and.
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.affiliation: Channing Division of Network Medicine, Department of Medicine and Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA; and.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA; Channing Division of Network Medicine, Department of Medicine and Department of Pathology, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA; Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA; and.
authors.forename: Shuji
authors.initials: S
authors.lastname: Ogino
authors.affiliation: Channing Division of Network Medicine, Department of Medicine and Division of Gastroenterology, Massachusetts General Hospital, Boston, MA.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
authors.affiliation: Department of Nutrition and Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA; Channing Division of Network Medicine, Department of Medicine and.
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.affiliation: Department of Nutrition and.
authors.forename: Kana
authors.initials: K
authors.lastname: Wu
mesh_terms: D000328:Adult; D000872:Anthocyanins / Q000494:pharmacology; D015179:Colorectal Neoplasms / Q000517:prevention & control; D004032:Diet; D005247:Feeding Behavior; D005260:Female; D044950:Flavanones / Q000494:pharmacology; D047309:Flavones / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D044948:Flavonols / Q000494:pharmacology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010936:Plant Extracts / Q000494:pharmacology*; D010945:Plants, Edible / Q000737:chemistry*; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D000872:Anthocyanins; D044950:Flavanones; D047309:Flavones; D005419:Flavonoids; D044948:Flavonols; D010936:Plant Extracts
keywords: anthocyanins; colorectal cancer; flavan-3-ols; flavanones; flavones; flavonoids; flavonols