Objective. Constipation and encopresis are common problems in children. Still today, the role of fiber in the treatment of chronic constipation in childhood is controversial. The aim of our study was to evaluate whether fiber supplementation is beneficial in the treatment of children with functional constipation with or without encopresis. We used glucomannan as the fiber supplement.

Methods. We evaluated the effect of fiber (glucomannan, a fiber gel polysaccharide from the tubers of the Japanese Konjac plant) and placebo in children with chronic functional constipation with and without encopresis in a double-blind, randomized, crossover study. After the initial evaluation, the patients were disimpacted with 1 or 2 phosphate enemas if a rectal impaction was felt during rectal examination. Patients continued with their preevaluation laxative. No enemas were given during each treatment period. Fiber and placebo were given as 100 mg/kg body weight daily (maximal 5 g/day) with 50 mL fluid/500 mg for 4 weeks each. Parents were asked to have children sit on the toilet 4 times daily after meals and to keep a stool diary. Age, frequency of bowel movements into the toilet and into the undergarment, presence of abdominal pain, dietary fiber intake, medications, and the presence of an abdominal and/or a rectal fecal mass were recorded on a structured form at the time of recruitment and 4 weeks and 8 weeks later. Children were rated by the physician as successfully treated when they had ≥3 bowel movements/wk and ≤1 soiling/3 weeks with no abdominal pain in the last 3 weeks of each 4-week treatment period. Parents made a global assessments to whether they believed that the child was better during the first or second treatment period.

Results. Forty-six chronically constipated children were recruited into the study, but only 31 children completed the study. These 31 children (16 boys and 15 girls) were 4.5 to 11.7 years of age (mean: 7 ± 2 years). All children had functional constipation; in addition, 18 had encopresis when recruited for the study. No significant side effects were reported during each 4-week treatment period. Significantly fewer children complained of abdominal pain and more children were successfully treated while on fiber (45%) as compared with placebo treatment (13%). Parents rated significantly more children (68%) as being better on fiber versus 13% as being better on placebo. The initial fiber intake was low in 22 (71%) children. There was no difference in the percentage of children with low fiber intake living in the United States (70%) and Italy (71%). Successful treatment (physician rating) and improvement (parent rating) were independent of low or acceptable initial fiber intake. The duration of chronic constipation ranged from 0.6 to 10 years (mean: 4.0 ± 2.5 years). Duration of constipation did not predict response to fiber treatment. Children with constipation only were significantly more likely to be treated successfully with fiber (69%) than those with constipation and encopresis (28%).

Conclusion. We found glucomannan to be beneficial in the treatment of constipation with and without encopresis in children. Symptomatic children who were already on laxatives still benefited from the addition of fiber. Therefore, we suggest that we continue with the recommendation to increase the fiber in the diet of constipated children with and without encopresis.

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