Increased intake of dietary fiber has been proposed to reduce the risk of inflammatory bowel disease.
However, few prospective studies have examined associations between long-term intake of dietary fiber and risk of incident Crohn's disease (CD) or ulcerative colitis (UC).
Dr Ashwin Ananthakrishnan and colleagues from Massachussetts, USA collected and analyzed data from 170,776 women, followed up over 26 years, who participated in the Nurses' Health Study, followed up for 3,317,425 person-years.
Dietary information was prospectively ascertained via administration of a validated semiquantitative food frequency questionnaire every 4 years.
|Apparent reduction appeared to be greatest for fiber derived from fruits|
Self-reported CD and UC were confirmed through review of medical records.
The researchers confirmed 269 incident cases of CD, and 338 cases of UC.
Compared with the lowest quintile of energy-adjusted cumulative average intake of dietary fiber, intake of the highest quintile was associated with a 40% reduction in risk of CD.
The team observed that this apparent reduction appeared to be greatest for fiber derived from fruits.
The researchers found that fiber from cereals, whole grains, or legumes did not modify risk.
In contrast, neither total intake of dietary fiber nor intake of fiber from specific sources appeared to be significantly associated with risk of UC.
Dr Ananthakrishnan's team comments, "Based on data from the Nurses' Health Study, long-term intake of dietary fiber, particularly from fruit, is associated with lower risk of CD but not UC."
"Further studies are needed to determine the mechanisms that mediate this association."