Baseline characteristics of patients
| Overall | FMT | Placebo | P values | |
| n | 51 | 25 | 26 | |
| Age (mean (SD)) | 36.39 (11.47) | 37.28 (12.48) | 35.54 (10.58) | 0.593 |
| Weight (mean (SD)) | 77.02 (17.86) | 76.60 (19.89) | 77.42 (16.07) | 0.872 |
| BMI (mean (SD)) | 25.99 (5.35) | 25.96 (5.84) | 26.02 (4.95) | 0.966 |
| Height (mean (SD)) | 1.72 (0.08) | 1.72 (0.09) | 1.72 (0.07) | 0.784 |
| Male (%) | 16 (31.4) | 8 (32.0) | 8 (30.8) | 1 |
| Type of IBS (%) | 0.591 | |||
| IBS with constipation | 17 (33.3) | 7 (28.0) | 10 (38.5) | |
| IBS with diarrhoea | 15 (29.4) | 7 (28.0) | 8 (30.8) | |
| IBS mixed | 19 (37.3) | 11 (44.0) | 8 (30.8) | |
| Continue use of IBS medication (%) | 29 (56.9) | 14 (56.0) | 15 (57.7) | 1 |
| Former tried IBS medication (%) | 43 (84.3) | 23 (92.0) | 20 (76.9) | 0.274 |
| Former tried new diet (%) | 38 (74.5) | 17 (68.0) | 21 (80.8) | 0.469 |
| Born by caesarean section (%) | 6 (12.2) | 3 (12.5) | 3 (12.0) | 1 |
| Breastfed (%) | 45 (93.8) | 21 (91.3) | 24 (96.0) | 0.941 |
| Birth control pills(%) | 9 (17.6) | 3 (12.0) | 6 (23.1) | 0.503 |
| PPI (%) | 8 (15.7) | 2 (8.0) | 6 (23.1) | 0.274 |
| Antimigraine (%) | 2 (3.9) | 1 (4.0) | 1 (3.8) | 1 |
| Asthma allergies (%) | 9 (17.6) | 6 (24.0) | 3 (11.5) | 0.424 |
| Painkiller (%) | 8 (15.7) | 4 (16.0) | 4 (15.4) | 1 |
| Circulatory (%) | 2 (3.9) | 2 (8.0) | 0 (0.0) | 0.453 |
| Antiviral (%) | 2 (3.9) | 1 (4.0) | 1 (3.8) | 1 |
| Topical steroid (%) | 2 (3.9) | 1 (4.0) | 1 (3.8) | 1 |
| Laxatives (%) | 2 (3.9) | 1 (4.0) | 1 (3.8) | 1 |
| Constipation drugs (%) | 3 (5.9) | 1 (4.0) | 2 (7.7) | 1 |
| Other medications (%) | 3 (5.9) | 1 (4.0) | 2 (7.7) | 1 |
| IBS-QoL score at inclusion (mean (SD)) | 41.07 (14.98) | 42.07 (14.75) | 40.11 (15.42) | 0.646 |
| IBS-SSS score at inclusion (mean (SD)) | 343.39 (86.61) | 341.68 (95.02) | 345.04 (79.56) | 0.892 |
BMI, body mass index; FMT, faecal microbiota transplantation; IBS-QoL, IBS-specific quality of life; IBS-SSS, IBS-severity scoring system; PPI, proton pump inhibitor.