Dietary isoflavone and the risk of colorectal adenoma: a case-control study in Japan.
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.
Akhter
M
M
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
Iwasaki
M
M
Yamaji
T
T
Sasazuki
S
S
Tsugane
S
S
D000236:Adenoma / Q000453:epidemiology* / Q000517:prevention & control; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D004032:Diet; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D007564:Japan; D008019:Life Style; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
D007529:Isoflavones