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.

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.