Manipulation of Intestinal Microbial Flora for Therapeutic Benefit in Inflammatory Bowel Diseases: Review of Clinical Trials of Probiotics, Prebiotics and Synbiotics

Pathogenesis of Inflammatory Bowel Diseases(Ulcerative Colitis, Crohn's disease and Pouchitis) includes an abnormal immunological response to disturbed intestinal microflora. Therapeutic strategies are designed to intervene in these abnormal host microbial communications. A novel approach in the last decade has been to use other bacteria or selective foods to induce beneficial bacteria to normalize inflammation. In this review we discuss rationale for such use and describe 46 clinical trials gleaned from the literature. Reports are divided into type, indications, and agents used. The search revealed 15 nonrandomized and 31 randomized trials. Of the latter 23 were double-blind and 8 were open-label randomized controlled. In 32 of the total, different probiotics were used, while 10 and 4 used different prebiotics or synbiotics respectively. In 14 nonrandomized trials, outcome was successful. In the randomized controlled trials 12 of 16 ulcerative colitis but only 2 of Crohn's disease trials of biotic therapy were successful. No superiority of any probiotic was clearly evident, but a multi-agent mixture, VSL3# may be better suited in ulcerative colitis and pouchitis while the probiotic Lactobacillus rhamnosus GG appears less useful in inflammatory bowel disease, especially Crohn's disease. Further studies with uniform stringent criteria are needed to provide proof of this therapy in inflammatory bowel disease.