According to the Rome III criteria,1, 2 abdominal pain-related functional gastrointestinal disorders (FGD) in children may be categorised as functional dyspepsia (FD), irritable bowel syndrome (IBS), abdominal migraine and functional abdominal pain (FAP). Because of their obscure pathophysiology, management of abdominal pain-related FGD remains difficult, prompting interest in new and safe treatment options.
Recently, probiotics, defined as ‘live microorganisms which when administered in adequate amounts confer a health benefit on the host’,3 have been proposed as treatment for FGD. While the exact mechanisms by which probiotics may exert their actions in patients with FGD are not fully understood, several mechanisms have been suggested. These include changes in colonic fermentation by displacement of gas-producing, bile salt-deconjugating bacteria strains, down-regulation of the local proinflammatory response, control of intestinal motor functions, and reducing visceral hypersensitivity by inducing the expression of u-opioid and cannabinoid receptors in human intestinal epithelial cells.4
Previously, four meta-analyses5–8 and one systematic review9 evaluated the effects of probiotics for the treatment of IBS, primarily in the adult population and reached slightly different conclusions. For adults, despite the equivocal results, the American College of Gastroenterology recently concluded that ‘in single organism studies, lactobacilli do not appear effective; bifidobacteria and certain combinations of probiotics demonstrate some efficacy.’10 Regarding the paediatric population, a Cochrane systematic review11 (search date: December 2006) concluded that there is no evidence that lactobacillus supplementation is effective in the management of children with recurrent abdominal pain. New studies12, 13 have been published since this meta-analysis, prompting interest in re-evaluating the role of probiotics in the management of abdominal pain-related FGD in children. With this systematic review, we aimed to update and synthesise the available randomised controlled clinical trial evidence of the likely effects of Lactobacillus rhamnosus GG (LGG) compared with placebo or no intervention in children affected by abdominal pain-related FGD. In contrast to previous meta-analyses, whether performed in adults or in children, we focused on a single probiotic microorganism. This is because the beneficial effects of probiotics seem to be strain specific, thus, pooling data on different strains may result in misleading conclusions. The choice of the probiotic LGG was determined by the fact that it is available and commonly used in many countries, and it has demonstrated efficacy in the treatment of some gastrointestinal conditions in children.14, 15