S1705 Diet Modulation in Conjunction With Fecal Microbiota Transplantation for Refractory Ulcerative Colitis: A Systematic Review of Emerging Strategies and Clinical Outcomes

Introduction: Ulcerative colitis (UC) is an idiopathic disease that causes recurring inflammation of the bowel mucosa. In refractory cases, fecal microbiota transplantation (FMT) has emerged as a potential treatment option. The fecal samples from a donor individual are transferred to a recipient's gut, promoting regeneration of the mucosa and forming a balanced gut environment. This helps support the gut microbiome, which aids in gut healing and promotes immunity. Diet plays a role in gut healing. This synergistic effect helps colonic inflammation and may lead to remission. Methods: A comprehensive search was carried out in PubMed, Google Scholar, and Science Direct from 2015 to 2025, using predefined search terms related to UC, FMT, and diet. Studies included adult refractory UC with both FMT and dietary interventions, as well as FMT alone, reporting clinical remission or mucosal healing outcomes. Articles on pediatric populations or non-UC inflammatory diseases were excluded. The data on clinical remission, outcomes, mucosal healing, adverse events, and risk of bias were extracted. Results: Nine randomized trials evaluated FMT combined with dietary interventions in refractory UC across diverse settings. Diets include UCED, anti-inflammatory regimens, or fibre. Comparators were FMT alone, standard medical therapy, or FMT with placebo fibre. Clinical remission rates favoured combination therapy in most studies: one reported 60% remission with FMT-AID vs 32.3% with SMT; another found 55.6% with FMT alone vs 22.2% with FMT + fibre. In one trial, a UCED-only group had the highest remission (40%). Mucosal healing was inconsistently reported. One study showed 36.4% healing with the FMT diet vs 8.7% with SMT. Adverse effects were mild to moderate; the risk of bias was moderate to high due to open-label designs and small samples. Conclusion: FMT with diet therapy can help patients with Refractory ulcerative colitis achieve better remission rates than using FMT alone. Mucosal healing data were inconsistent, but findings suggest the combined treatment approach. Combined FMT and Diet therapy were well tolerated, showing mild to moderate adverse effects, and the risk of bias was moderate to high. Until then, FMT with diet remains a promising but investigational treatment of refractory ulcerative colitis.