Dietary isoflavone and the risk of colorectal adenoma: a case-control study in Japan

Br J Cancer. 2009 Jun 2;100(11):1812-6. doi: 10.1038/sj.bjc.6605088. Epub 2009 May 5.


We conducted a case-control study in a Japanese population to investigate the association between dietary isoflavone intake and the risk of colorectal adenoma. Participants who underwent magnifying colonoscopy with dye spreading as part of a cancer screening programme responded to a self-administered questionnaire, which included lifestyle information and intake of 145 food items, before the colonoscopy. A total of 721 case and 697 control subjects were enrolled. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression models. We found a significant inverse association between dietary isoflavone intake and the risk of colorectal adenoma in men and women combined. However, the inverse association was not linear; rather, all quartiles above the first showed a similar decrease in risk, with multivariable-adjusted ORs and 95% CIs compared with the lowest quartile of 0.77 (0.57-1.04), 0.76 (0.56-1.02) and 0.70 (0.51-0.96) in the second, third and highest quartiles, respectively (P for trend=0.03). Of interest, the observed association was more prominent in women than in men. The observed ceiling effect associated with higher isoflavone intake suggests that a lower intake of dietary isoflavone might be associated with an increased risk of colorectal adenoma in Japanese populations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / epidemiology*
  • Adenoma / prevention & control
  • Adult
  • Aged
  • Case-Control Studies
  • Colorectal Neoplasms / epidemiology*
  • Colorectal Neoplasms / prevention & control
  • Diet*
  • Female
  • Humans
  • Isoflavones / pharmacology*
  • Japan
  • Life Style
  • Male
  • Middle Aged
  • Risk Factors


  • Isoflavones