Soy Polysaccharide Fiber for the Treatment of Chronic Constipation in Children: a Randomized, Double-blind Trial (SOYFIBER)

Soy Polysaccharide Fiber for the Treatment of Chronic Constipation in Children: a Randomized, Double-blind Trial

Soy Polysaccharide Fiber for the Treatment of Chronic Constipation in Children: a Randomized, Double-blind Trial

The study tested the hypothesis that soy polysaccharide fiber reduces clinical symptoms of chronic constipation.

The study was performed out at outpatient clinic of Pediatric Gastroenterology at the Federal University of São Paulo (São Paulo, Brazil), located in the southeastern region of Brazil. It is a public referral hospital for pediatric gastroenterology attendance in the Metropolitan area of the São Paulo and in Brazil. In general, the patients go to consultation after a referral from a primary care center. Study design and sample size The design was a randomized double-blind trial, placebo-controlled study. Sample size was calculated by the formula of comparison of two proportions, using clinical improvement as a primary outcome. It had been previously calculated that a minimum of 14 patients in each group will give a power of 80% to detect a effect size of 50% with significance at the level of 5% (one-sided).

Dietary Supplement: Soy polysaccharide fiber First, disimpaction was carried out with phosphate enemas for 1 to 3 days. After the children have been "cleaned out", they received a soy polysaccharide fiber supplement (powder containing 70 g of fiber/100 g) or placebo (purified soy extract, with no fiber) for 6 weeks. Fiber and placebo were given as a standard dose for the different age groups (median of 0,57 g/kg/day) - 2 to 5 years, 10 g/day; 6 to 9 years, 15 g/day; and > 10 years, 20 g/day. The child that had fecal impaction (a dilated rectum filled with a large amount of stool on rectal examination) during the follow-up was treated by administering phosphate enemas for 1 to 3 consecutive days. Arms: Soy polysaccharide fiber, purified soy extract, with no fiber Other Names: Soy polysaccharide fiber (Pró-fibra®) Purified soy extract, with no fiber (Soyac®)

Colonic transit time was evaluated by the technique of Metcalf et al. In brief, a plain abdominal radiograph performed after 24 hours from the last ingestion of 3 sets of 20 distinctive radio-opaque markers taken on 3 consecutive days. In the presence of > 20% of the markers, a further radiography was taken on the 7th day. The colonic segments were delimitated according to Arhan et al. The patients were instructed to collect the 3-day stools separately from the urine. The collected stools were used to determine the fecal weight and moisture.

Inclusion Criteria: Patients over two years of age at first consultation and chronic functional constipation were included. Chronic constipation was defined by the occurrence of any of the following, for at least 2 weeks, independently of stool frequency: passage of hard, scybalous, pebble-like or cylindrical cracked stools, straining or painful defecation, passage of large stools that may clog the toilet, or stool frequency less than 3 per week. Exclusion Criteria: The exclusion criteria applied were organic constipation, regular use of dietary fiber in the preceding 30 days or drugs causing constipation.