Dietary fiber and whole-grain consumption in relation to colorectal cancer in the NIH-AARP Diet and Health Study

Am J Clin Nutr. 2007 May;85(5):1353-60. doi: 10.1093/ajcn/85.5.1353.

Abstract

Background: Whether the intake of dietary fiber can protect against colorectal cancer is a long-standing question of considerable public health import, but the epidemiologic evidence has been inconsistent.

Objective: The objective was to investigate the relation between dietary fiber and whole-grain food intakes and invasive colorectal cancer in the prospective National Institutes of Health-AARP Diet and Health Study.

Design: The analytic cohort consisted of 291 988 men and 197 623 women aged 50-71 y. Diet was assessed with a self-administered food-frequency questionnaire at baseline in 1995-1996; 2974 incident colorectal cancer cases were identified during 5 y of follow-up. The Cox proportional hazards model was used to estimate the relative risks (RRs) and 95% CIs.

Results: Total dietary fiber intake was not associated with colorectal cancer. The multivariate RR for the highest compared with the lowest intake quintile (RR(Q5-Q1)) was 0.99 (95% CI: 0.85, 1.15; P for trend = 0.96). In analyses of fiber from different food sources, only fiber from grains was associated with a lower risk of colorectal cancer (multivariate RR(Q5-Q1): 0.86; 95% CI: 0.76, 0.98; P for trend = 0.01). Whole-grain intake was inversely associated with colorectal cancer risk: the multivariate RR(Q5-Q1) was 0.79 (95% CI: 0.70, 0.89) for the whole cohort (P for trend < 0.001). The association with whole grain was stronger for rectal than for colon cancer.

Conclusions: In this large prospective cohort study, total dietary fiber intake was not associated with colorectal cancer risk, whereas whole-grain consumption was associated with a modest reduced risk.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Aged
  • Cohort Studies
  • Colorectal Neoplasms / epidemiology*
  • Colorectal Neoplasms / etiology
  • Colorectal Neoplasms / prevention & control
  • Diet*
  • Dietary Fiber / administration & dosage*
  • Edible Grain*
  • Female
  • Health Surveys*
  • Humans
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Odds Ratio
  • Proportional Hazards Models
  • Prospective Studies
  • Risk Factors
  • Surveys and Questionnaires