Therapeutic modulation of gut microbiota in inflammatory bowel disease: More questions to be answered

Patients with inflammatory bowel disease (IBD) exhibit impaired control of the microbiome in the gut, and 'dysbiosis' is commonly observed. Western diet is a risk factor for the development of IBD, but it may have different effects on gut microbiota between IBD and non-IBD individuals. Exclusive enteral nutrition (EEN) can induce remission in pediatric Crohn's disease with a decrease in gut microbial diversity. Although there are some theoretical benefits, actual treatment effects of prebiotics and probiotics in IBD vary. High-quality studies have shown that VSL#3 (a high-potency probiotic medical food containing eight different strains) exhibits benefits in treating ulcerative colitis, and gut microbial diversity is reduced after treated with VSL#3 in animal models. The effect of fecal microbiome transplantation on IBD is controversial. Increasing microbial diversity compared with impaired handling of bacteria presents a dilemma. Antibiotics are the strongest factors in the reduction of microbiome ecological diversity. Some antibiotics may help to induce remission of the disease. Microbiome alteration has been suggested to be an intrinsic property of IBD and a potential predictor in diagnosis and prognosis. However, the effects of therapeutic modulations are variable; thus, more questions remain to be answered.