Efficacy and Safety of FMT for the Treatment of IBS-D and Mental Health Comorbidity in Young Adults

Inclusion criteria

• ✓. Voluntarily sign informed consent, be able to comply with the protocol and be able to carry out related procedures, including the completion of diary during the induction period and throughout the study period.
• ✓. Age between 18 and 29 years old (including two-end values, based on the date of signing the Master Informed consent), regardless of gender.
• ✓. IBS-D patients with clinical symptoms meeting the Rome IV definition, that is, the course of disease for at least 6 months, repeated abdominal pain in the past 3 months, an average of at least 1 day per week, combined with two or more of the following conditions: (a) Abdominal pain is related to defecation; （b） Abdominal pain accompanied by changes in the frequency of defecation; （c） Abdominal pain accompanied by changes in fecal trait. When abnormal stool occurred in the last 3 months, the proportion of abnormal stool was \>25% for Bristol fecal trait type 6 or 7, and \<25% for Bristol fecal trait type 1 or 2；and a Hamilton Depression Scale score: 20-34 and/or a Hamilton Anxiety Scale score: 14-28 were evaluated as depressed or anxious patients;
• ✓. Colonoscopy has been completed within 12 months before the run-in period. The ileocecal part should be observed during endoscopy, and the ileocecal flap image recording should be included in the report. They may be included if one of the following conditions is met: (i) The colonoscopy report is normal; (ii) Abnormalities reported by colonoscopy, such as hemorrhoids and intestinal polyps (diameter ≤5mm and number ≤3), were determined by the investigator to be eligible for inclusion; (iii) Colonoscopy reported that the diameter of intestinal polyps was \>5mm or the number of intestinal polyps was \>3; after endoscopic treatment, the diameter of residual intestinal polyps was ≤5mm and the number of intestinal polyps was ≤3, and the investigators determined that they could be included in the group.
• ✓. The patient had not used any relief drugs or analgesics in the 14 days prior to randomization.
• ✓. During the period from the signing of the master informed consent to the end of the final study visit, patients agreed to maintain their usual diet and lifestyle, such as no changes in dietary structure or exercise patterns.