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252 Chapter 12 movements after treatment (mean defecation frequency: PHGG: 5.0 ± 1.7 vs lactulose: 6.0 ± 1.1, P < .05). The authors reported that baseline daily fiber intake and diet were similar in both groups. In succession to the study by Loening-Baucke  et al. , glucomannan was evaluated in a placebo-controlled 4-week RCT in 72 children by Chmielewska  et al . 16 The authors found no significant difference between both groups with respect to therapeutic success at the end of the study. Abdominal pain occurred significantly less in the glucomannan group at the end of the study. Median number of episodes of abdominal pain per week (interquartile range); glucomannan: 0 (0–2) vs placebo: 0 (0–1), P < .01. Weber  et al.  described the use of a dietary fiber mixture in comparison to placebo in 54 children. 17 Although the defecation frequency did not differ between groups at the end of treatment (fiber: 1.1 ± 0.5 vs placebo: 0.9 ± 0.3), there was a significantly larger improvement in daily bowel movements compared to baseline in the fiber group. The mean increase in defecation frequency per day in the fiber mixture group was 0.5 ± 0.4 versus 0.2 ± 0.4 in the placebo group ( P = .01). The median dietary fiber intake was similar in both groups before the start of the clinical trial. Probiotics Probiotics contain viable microorganisms which alter the microflora of the host and exert beneficial health effects in this host. 6 It has been suggested that certain microorganisms affect colonic motility by softening the stools and by influencing secretion and/or absorption of water and electrolytes. 18 Also, they may influence smooth muscle cell contractions, directly manipulating peristalsis. 2 Probiotics can also influence intraluminal pH; by lowering the pH they can affect intestinal motility. 19 Furthermore, it is likely that metabolic processes play a role; substances involved in microbiota metabolism that may influence colonic motility include methane and butyrate. 2,20 We identified four systematic reviews 11,13,21,22  describing five RCTs and one subsequent RCT which was not described in any of the previous systematic reviews. 23 Lactobacillus rhamnosus GG Banaszkiewicz  et al. assessed the effectiveness of  Lactobacillus rhamnosus GG (ATCC 53103) as an adjunct to lactulose, comparing this with placebo added to lactulose treatment in 84 children. 18 The authors found no significant difference in defecation frequency, fecal incontinence episodes or straining at defecation between the two groups. The side effect profile was similar in both groups; with abdominal being the most commonly reported adverse effect.