Dietary fiber and colorectal cancer risk: the multiethnic cohort study.
OBJECTIVE
To investigate the association of dietary fiber with colorectal cancer


METHODS
A total of 85,903 men and 105,108 women completed a quantitative food frequency questionnaire in 1993-1996. A total of 1,138 men and 972 women were subsequently diagnosed with adenocarcinoma of the large bowel. Cox proportional hazards models were used to calculate multivariate adjusted relative risks (RR) and 95% confidence intervals (95% CI) for colorectal cancer.


RESULTS
High consumers of dietary fiber were more active, less overweight, and less likely to be cigarette smokers than low consumers in both sexes. Fiber was inversely associated with colorectal cancer risk after adjustment for age and ethnicity in men (RR = 0.49; 95% CI, 0.41-0.60, highest vs. lowest quintile) and women (RR = 0.75; 95% CI, 0.61-0.92). After further adjustment for lifestyle and dietary factors, the inverse association remained significant in men (RR = 0.62; 95% CI, 0.48-0.79), but not in women (RR = 0.88; 95% CI, 0.67-1.14). Adjustment for the combination of replacement hormone use with either cigarette smoking or body mass index accounted for the lack of association with fiber in women.


CONCLUSIONS
Dietary fiber was inversely associated with colorectal cancer risk in men, but its relation to replacement hormone use and other factors affected its inverse association in women.
Nomura
Abraham M Y
AM
Epidemiology Program, Cancer Research Center of Hawaii, University of Hawaii, Honolulu, HI 96813, USA. abe@crch.hawaii.edu.
Hankin
Jean H
JH
Henderson
Brian E
BE
Wilkens
Lynne R
LR
Murphy
Suzanne P
SP
Pike
Malcolm C
MC
Le Marchand
Loic
L
Stram
Daniel O
DO
Monroe
Kristine R
KR
Kolonel
Laurence N
LN
D000230:Adenocarcinoma / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D000368:Aged; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D004043:Dietary Fiber / Q000494:pharmacology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D044382:Population Groups; D012307:Risk Factors