Dietary fiber is thought to protect against colorectal cancer. However, this has recently been challenged by studies illustrating no protective effect.
In this study, a research team from Europe prospectively examined the association between dietary fiber intake and incidence of colorectal cancer.
The team evaluated 519,978 individuals (25 to 70 years), who were taking part in the EPIC study. Subjects were recruited from 10 European countries.
|The protective effect was greatest for the left side of the colon.|
All participants completed a dietary questionnaire between 1992 and 1998. They were then followed-up for incidence of cancer.
The team estimated relative risks from fiber intake, categorized by sex-specific, cohort-wide quintiles. Also, from linear models relating the hazard ratio to fiber intake expressed as a continuous variable.
Overall, follow-up consisted of 1,939,011 person-years.
The data for 1065 reported cases of colorectal cancer were included in the analysis.
The research team found that dietary fiber in foods was inversely related to incidence of large bowel cancer (adjusted relative risk 0.75). They determined that the protective effect was greatest for the left side of the colon, and least for the rectum.
Once this data was calibrated with more detailed dietary information, the adjusted relative risk for the highest versus lowest quintile of fiber from food intake was 0.58.
The team did not identify any one food source of fiber that was more protective than others. They did not investigate non-food supplement sources of fiber.
Dr Sheila Bingham's team concluded, "In populations with low average intake of dietary fiber, an approximate doubling of total fiber intake from foods could reduce the risk of colorectal cancer by 40%".