RESUMEN
CONTEXT: Inflammatory bowel diseases are chronic, relapsing diseases that compromise life quality and expectancy. The increased incidence and prevalence of these diseases reinforce the need for research on prevention, therapy, and management innovations. Synbiotics (ie, probiotic plus prebiotic combinations) are suggested as an alternative or complementary therapy to conventional treatments for inflammatory bowel disease. OBJECTIVE: The aim for this systematic review was to gather and analyze data from randomized controlled trials to provide more information to increase the current evidence level about the safety and efficacy of synbiotic use as a supplemental treatment for ulcerative colitis. DATA SOURCES: Searches were performed in the Medline, Science Direct, Scielo, Scopus, and Embase databases between January 2017 and March 2019, using the keywords "colitis" and "synbiotics". DATA EXTRACTION: The data extraction method performed for each trial was based on the recommendations of the Consolidated Standards of Reporting Trials for randomized clinical trials. The trials included in this meta-analysis presented low risk of bias, based on the Cochrane Handbook for Systematic Reviews of Interventions guidelines. DATA ANALYSIS: The results demonstrated that synbiotics significantly improved colonic endoscopic and histologic scores, the Clinical Activity Index, serum C-reactive protein levels, intestinal microbiota, Bowel Habits Index, and levels of messenger RNAs, tumor necrosis factor-α, interleukin-1α, interleukin-10, and myeloperoxidase in the patients. In addition, the use of synbiotics increased probiotic microorganisms, reduced proinflammatory colonic cytokines, and elevated anti-inflammatory cytokines. CONCLUSIONS: Therefore, the results of this meta-analysis reinforce the evidence that synbiotics provide benefits to patients when used as an alternative or complementary therapy for those with ulcerative colitis.