The hypothesis that increased intake of dietary fiber lowers the risk of colorectal cancer (CRC) has been weakened by results from studies that have not detected this association.
In this study, researchers from Bethesda, Maryland, investigated the association between dietary fiber intake and risk of CRC in a cohort of women. The cohort had prospectively answered a food frequency questionnaire (FFQ).
The team studied 45,491 women in the Breast Cancer Detection Demonstration Project (BCDDP) follow-up cohort.
The 62-item FFQ was administered between 1987 and 1989 to assess dietary intake.
Participants also received follow-up questionnaires between 1992 and 1995, and 1995 and 1998, on which they reported any cancers.
The team also identified cases through searches of the National Death Index and state cancer registries.
|There was no association between total fiber intake and colorectal cancer.|
|International Journal of Epidemiology|
They used Cox proportional hazard regression to generate risk ratios for quintiles of total fiber intake and fiber subtypes.
Over a mean follow-up time of 8.5 years the research team identified 487 colorectal cancer cases.
The team determined that the 10th and 90th percentiles of dietary fiber intake were 5.4g and 18.2g, respectively.
For total fiber they found no association with colorectal cancer (fifth versus first quintile, RR = 0.94).
Furthermore, analyses by subgroup of fiber, and by anatomical subsite, did not reveal any stronger inverse associations.
Dr Volker Mai's team concluded, "Within a cohort of older women characterized by a relatively low fiber intake, there was little evidence that dietary fiber intake lowers the risk of colorectal cancer".