Using cereal to increase dietary fiber intake to the recommended level and the effect of fiber on bowel function in healthy persons consuming North American diets

Am J Clin Nutr. 2008 Nov;88(5):1256-62. doi: 10.3945/ajcn.2008.25956.


Background: Dietary fiber intake remains low despite increasing evidence for its health benefits, including laxation.

Objective: We aimed to assess the effects of increasing fiber intake on bowel habits and gastrointestinal tolerance in healthy persons consuming a typical Canadian or US diet.

Design: Under a randomized crossover design, 23 free-living participants consumed a typical Canadian or US diet (35% fat, 12 g fiber/d) and received 25.0-28.7 g fiber/d from each of 5 breakfast cereals: All-Bran (AB), Bran Buds with Corn (BBC), Bran Buds with Psyllium (BBP), BBC with viscous fiber blend (VFB), or a low-fiber control for 3 wk, with each study arm separated by a washout of >/=1 wk. Seven-day stool collections and a symptom diary were obtained during the last week of each study arm.

Results: All study cereals induced significant (P < 0.05) increases in fecal bulk from the control diet at 128 +/- 38 g to 199 +/- 56, 199 +/- 57, 247 +/- 87, and 197 +/- 63 g with consumption of AB, BBC, BBP, and VFB, respectively; less intestinal transit time; and significantly (P < 0.05) greater bowel movement frequency. Despite the increased activity of the bowel, a positive level of comfort was maintained. BBP was more effective than other cereals in terms of increasing fecal wet weight (P < 0.05).

Conclusion: Water-insoluble dietary fibers (ie, AB and BBC) and their mixtures with water-soluble fibers (ie, BBP and VFB) in the form of breakfast cereals (2.5 servings/d) proved to be a practical way of increasing fiber intake to recommended levels, while maintaining a good level of tolerance.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abdominal Pain / epidemiology
  • Adult
  • Breath Tests
  • Colon / physiology
  • Cross-Over Studies
  • Defecation / drug effects*
  • Defecation / physiology
  • Dietary Fiber / administration & dosage*
  • Dietary Fiber / adverse effects
  • Dietary Fiber / metabolism*
  • Edible Grain*
  • Feces / chemistry
  • Female
  • Flatulence / epidemiology
  • Gastrointestinal Transit / physiology*
  • Humans
  • Male
  • Middle Aged
  • Solubility