Faecal pH, lactate, succinate, SCFA, absolute and relative bacterial abundance and bacterial diversity on pooled 5-day samples in IBS and healthy subjects during their habitual diet
| IBS (n=27) | Healthy control (n=6) | p Value | |
|---|---|---|---|
| pH | 7.19 (7.07–7.31) | 7.17 (6.63–7.72) | 0.916 |
| Lactate (g/100 g)* | 0.02 (0.02–0.03) | 0.02 (0–0.04) | 0.375 |
| Succinate (g/100 g)* | 0.03 (0.02–0.03) | 0.04 (0.02–0.06) | 0.063 |
| SCFA concentration (µmol/g) | |||
| Total SCFA | 81.9 (72.3–91.5) | 93.4 (58.6–128) | 0.334 |
| Butyrate | 15.6 (13.0–18.1) | 18.9 (9.61–28.3) | 0.283 |
| Propionate | 15.8 (13.6–18.0) | 17.6 (9.53–25.6) | 0.526 |
| Acetate | 42.5 (37.4–47.5) | 44.7 (27.5–61.9) | 0.715 |
| Isobutyrate | 1.92 (1.66–2.17) | 3.10 (2.52–3.68) | <0.001 |
| Isovalerate | 2.99 (2.56–3.43) | 5.06 (3.92–6.19) | <0.001 |
| Valerate | 2.28 (1.73–2.83) | 3.70 (1.62–5.78) | 0.044 |
| Caproate† | 0.95 (0.58–1.32) | 0.46 (−0.12–1.04) | 0.175 |
| Absolute abundance (Log10 copies of 16S rRNA gene/g) | |||
| Total bacteria | 9.85 (9.72–9.98) | 9.82 (9.61–10.0) | 0.861 |
| Clostridium cluster IV | 8.40 (8.20–8.59) | 8.37 (7.97–8.76) | 0.892 |
| Faecalibacterium prausnitzii | 7.86 (7.68–8.05) | 7.76 (7.12–8.39) | 0.643 |
| Clostridium cluster XIVa | 8.26 (8.11–8.41) | 8.04 (7.66–8.41) | 0.193 |
| 7.64 (7.46–7.83) | 7.50 (6.90–8.10) | 0.518 | |
| Lactobacilli | 6.27 (6.03–6.51) | 5.94 (5.49–6.39) | 0.219 |
| Bifidobacteria | 7.61 (7.37–7.86) | 8.07 (7.55–8.58) | 0.104 |
| Akkermansia muciniphila | 4.07 (3.42–4.72) | 4.50 (2.53–6.47) | 0.571 |
| Ruminococcus gnavus | 7.20 (7.06–7.34) | 6.96 (6.70–7.22) | 0.129 |
| Ruminococcus torques | 6.09 (5.83–6.34) | 6.74 (6.37–7.11) | 0.025 |
| Relative abundance (percentage of total bacteria) | |||
| Clostridium cluster IV | 4.05 (3.34–4.77) | 3.73 (2.39–5.07) | 0.687 |
| F. prausnitzii | 1.31 (0.89–1.74) | 1.18 (0.19–2.16) | 0.778 |
| Clostridium cluster XIVa | 2.81 (2.40–3.22) | 1.82 (0.97–2.67) | 0.037 |
| Roseburia | 0.82 (0.57–1.06) | 0.67 (0.13–1.22) | 0.609 |
| Lactobacilli | 0.07 (0.01–0.13) | 0.02 (0–0.03) | 0.412 |
| Bifidobacteria | 1.33 (0.53–2.13) | 2.18 (0.48–3.87) | 0.348 |
| A. muciniphila | 0.01 (0–0.02) | 0.01 (0–0.03) | 0.756 |
| R. gnavus | 0.30 (0.20–0.40) | 0.16 (0.04–0.28) | 0.204 |
| R. torques | 0.03 (0.01–0.06) | 0.12 (0.01–0.23) | 0.008 |
| Diversity (Shannon index) | |||
| Clostridium cluster XIV | 1.83 (1.67–1.98) | 1.64 (1.35–1.93) | 0.310 |
Differences in cohorts were analysed by unpaired t test. Statistically significant differences are shown in bold based upon p≤0.05 for pH, lactate and succinate, p≤0.006 for SCFA concentrations, p≤0.005 for absolute and p≤0.006 for relative bacterial abundance after Bonferroni correction.
*Due to difficulties in analysis, for lactate, IBS n=8 and healthy controls n=2.
†Due to difficulties in analysis, for caproate, IBS n=18 and healthy controls n=5.
SCFA, short-chain fatty acid.