A review of nine studies with 640 children up to age 18 with functional constipation, which has no known physical cause, found that fiber supplements were somewhat better than placebos at reducing kids' abdominal pain and improving frequency and consistency of stools.

Other common non-drug treatments -- including prebiotics and probiotics, which help restore the digestive tract's balance of "good bacteria," increased water intake or behavioral therapy -- were deemed to be of little use, a finding that puzzles some doctors.

Study author Dr. Merit Tabbers, a pediatric gastroenterologist at Emma Children's Hospital in Amsterdam, pointed out that a lack of well-designed trials on children's constipation made it difficult to determine how credible the results really are. The results should be viewed cautiously, said the authors, noting future studies of high quality and uniform standards are needed to obtain definitive answers.

The study is published in the September 26 online edition and the October print issue of the journal Pediatrics.

Constipation affects many small kids who eat lots of processed foods. Low-fiber, "white" diets, replete with bread, pasta, rice, crackers and dairy products, are mostly to blame for the 3% estimated prevalence of chronic constipation among children in the Western world, experts said. In addition to infrequent stools, the condition is characterized by abdominal pain and "fecal incontinence," or uncontrollable soiling caused by leaking stool.

Over time, chronic constipation may impair a child's development and disrupt psychological and social functioning, the authors pointed out.

From the September 27, 2011, Prepared Foods' Daily News.