Effect of the dietary fiber glucomannan on chronic constipation

OBJECTIVE: Inadequate dietary fiber intake is a widely accepted explanation for chronic constipation in children with severe brain damage. The aim of our study was to evaluate the efficacy of glucomannan, a soluble fiber, as a treatment for chronic constipation in these children. STUDY DESIGN: Twenty children with severe brain damage and chronic constipation were randomly assigned to double-blind treatment with either glucomannan (n = 10) or placebo (n = 10) for 12 weeks. Stool habits, total and segmental gastrointestinal transit times, and anorectal motility were evaluated in all children before and after the treatment period. RESULTS: Glucomannan significantly increased (P <.01) stool frequency, whereas the effect of placebo was not significant. Laxative or suppository use was significantly reduced (P <.01) by glucomannan but was not affected by placebo. Clinical scores of stool consistency were significantly improved and episodes of painful defecation per week were significantly reduced by glucomannan (P <.01) but not by placebo. However, neither glucomannan nor placebo had a measurable effect on total and segmental transit times. CONCLUSIONS: In neurologically impaired children, glucomannan improves stool frequency but has no effect on colonic motility.