The role of dietary fiber in the prevention of colorectal (referring to the rectum and colon) cancer is unclear, according to the results of a new study.
Researchers from the Aichi Cancer Center Research Institute in Nagoya, Japan examined the association of dietary fiber with the risk of colorectal cancer in a population with a high incidence of cancer and a low fiber intake.
In the study, scientists analyzed the data from the Japan Collaborative Cohort Study. From 1988 to 1990, 43,115 men and women aged 40 to 79 years completed a questionnaire on dietary intake and other factors. Intake of dietary fiber was estimated using a food frequency questionnaire. Rate ratios (RR) were computed by fitting proportional hazards models. During the mean follow-up of 7.6 years, 443 colorectal cancer cases were recorded.
In all participants, researchers found a decreasing trend in risk of colorectal cancer with increasing intake of total dietary fiber; the multivariate-adjusted RRs across quartiles were 1.00, 0.96, 0.72 and 0.73. This trend was exclusively detected for colon cancer: the corresponding RRs were 1.00, 0.90, 0.56 and 0.58.
The decrease in RRs with increasing intake of dietary fiber was larger in men than in women. No material differences appeared in the strength of associations with the risk between water-soluble and insoluble dietary fiber. For food sources of fiber, bean fiber intake was somewhat inversely correlated with colorectal cancer risk.
Researchers concluded that there may be potential protective effects of dietary fiber against colorectal cancer, mainly against colon cancer. However, the role of dietary fiber in the prevention of colorectal cancer seems to remain inconsistent, and further investigations in various populations are warranted.
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