Table 3.
Between-group comparisons of faecal SCFA at baseline and 4-week follow-up in the control and LFD group†
| Control group (n 34) | LFD group (n 32) | ANCOVA (n 66) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Baseline | Follow-up | Baseline | Follow-up | |||||||
| SCFA | Mean | sd | Mean | sd | Mean | sd | Mean | sd | Estimate‡ | P value‡ |
| Total SCFA, conc | 57 | 21 | 55 | 19 | 54 | 20 | 54 | 25 | –0·89 | 0·87 |
| Acetic acid, conc | 32 | 12 | 31 | 11 | 31 | 12 | 31 | 16 | 0·20 | 0·95 |
| Butyric acid, conc | ||||||||||
| Median | 8·6 | 9·2 | 9·8 | 4·9 | 8·9 | 5·2 | –0·68 | 0·58 | ||
| 25th, 75th percentile | 7·2, 14 | 5·8, 14 | ||||||||
| Propionic acid, conc | 8·9 | 3·9 | 8·9 | 4·7 | 8·7 | 3·6 | 8·8 | 4·2 | –0·71§ | 0·009§,* |
| Iso-valeric acid, conc | 1·9 | 0·82 | 1·8 | 0·61 | 1·8 | 0·94 | 1·7 | 0·78 | –0·09 | 0·62 |
| Valeric acid, conc | ||||||||||
| Median | 1·3 | 0·47 | 1·4 | 0·67 | 1·3 | 1·2 | –0·90 § | 0·003§,* | ||
| 25th, 75th percentile | 0·91, 1·5 | 0·89, 1·5 | ||||||||
| Iso-butyric acid, conc | 1·3 | 0·51 | 1·3 | 0·37 | 1·2 | 0·60 | 1·2 | 0·52 | –0·07 | 0·55 |
| Caproic acid, conc|| | 0·57 | 0·67 | 0·58 | 0·66 | 0·54 | 0·64 | 0·44 | 0·50 | –0·03 | 0·72 |
| Acetic acid, % | 57 | 6·0 | 57 | 7·3 | 57 | 6·3 | 58 | 6·6 | –0·03 | 0·98 |
| Butyric acid, % | 18 | 5·7 | 17 | 4·8 | 18 | 5·3 | 16 | 3·7 | –0·71 | 0·48 |
| Propionic acid, % | 16 | 3·8 | 16 | 4·5 | 16 | 3·5 | 16 | 2·9 | 0·56 | 0·42 |
| Iso-valeric acid, % | 3·8 | 1·8 | 3·7 | 1·7 | 3·5 | 1·6 | 3·7 | 1·8 | 0·17 | 0·65 |
| Valeric acid, % | 2·4 | 0·93 | 2·6 | 1·0 | 2·5 | 0·86 | 2·6 | 0·98 | –0·05 | 0·79 |
| Iso-butyric acid, % | 2·6 | 1·1 | 2·6 | 0·96 | 2·4 | 0·97 | 2·5 | 1·0 | 0·06 | 0·79 |
| Caproic acid, %|| | ||||||||||
| Median | 0·72 | 0·79 | 0·98 | 1·1 | 0·92 | 1·0 | 0·01 | 0·92 | ||
| 25th, 75th percentile | 0·12, 1·7 | 0, 1·6 | ||||||||
P < 0·05.
SCFA concentrations (‘conc’, mmol/kg faeces) and percentages (‘%’, of total SCFA) are presented as means with sd or medians with 25th and 75th percentile. SCFA, short-chain fatty acids; LFD, low FODMAP diet; FODMAP, fermentable oligosaccharides, disaccharides, monosaccharides and polyols.
Between-group comparison: ANCOVA models were fitted with follow-up values as response variable and with baseline values and diet group as explanatory variables. Estimated difference between the diet groups at follow-up (control as reference) with corresponding P group value from ANCOVA, except where specified.
Estimated baseline values × diet group interaction (control as reference) with corresponding P interaction value from ANCOVA.
ANCOVA performed on square root transformed baseline and follow-up values.