Table 2.
Fiber and prebiotic intervention studies in adult IBD and their impact on the gut microbiome.
| Intervention | Duration | Study Type | Disease | Participants | Analysis Methodology | Key Microbiome Outcomes | Reference |
|---|---|---|---|---|---|---|---|
| Remission | |||||||
| (1) POS 10 g bd or (2) MES 500 mg tds or (3) both | 1 year | Randomized controlled trial | UC | n = 7 POS | GC—stool taken from rectum using rectoscopy at baseline and post intervention | Significant increase in butyrate after POS (6.1 to 9.2 μmol/g). Trend towards an increase in acetate. | [69] |
| 60 g oat bran (20 g/day DF) daily | 3 months | Prospective intervention study | UC | n = 19 oat bran | GC—stool collected every 4 weeks | 36% increase in butyrate after 4 weeks on oat bran. No significant differences in other SCFA. | [67] |
| LFD or iSAD | 4 weeks with 2-week washout | Randomized cross-over study | UC—remissive and active disease | n = 17 | 16S rRNA sequencing and LC-MS—stool collected at baseline and post intervention | Trend towards an increase in Faith’s alpha diversity after LFD. Significant shift in beta diversity from baseline in LFD group but not iSAD. LFD led to a significant increase in Bacteroidetes and significant decrease in Actinobacteria. Faecalibacterium prausnitzii was increased in the LFD group. Acetate increased after the LFD and iSAD. Tryptophan decreased on the iSAD and increased on the LFD. | [68] |
| Active disease | |||||||
| 15 g/day FOS | 4 weeks | Randomized double-blinded placebo-controlled trial | CD | n = 54 FOS and n = 49 placebo | FISH—fresh stool samples at baseline and post intervention | No significant differences in bifidobacteria or Faecalibacterium prausnitzii. | [55] |
| 15 g/day FOS | 3 weeks | Prospective intervention study | CD | n = 8 FOS | FISH—stool and mucosal biopsy samples at baseline and post intervention | Significant increase in stool but not mucosal bifidobacteria. No significant changes in total bacteria, Clostridium coccoides, Eubacterium rectale or Bacteroides. Those who entered disease remission (n = 4) had an increase of mucosal total bacteria and bifidobacteria. | [56] |
| 10 g bd of OF-IN | 4 weeks | Randomized double-blinded placebo-controlled trial | CD—remissive and active disease | n = 34 OF-IN and n = 33 in placebo | Real-time PCR—stool sample | OF-IN led to a significant decrease in Ruminococcus gnavus and increase in Bifidobacterium longum. No significant change in F. prausnitzii. Significant positive correlation between improved disease activity (in active CD) and B. longum in OF-IN group. | [57] |
| 7.5 g/day or 15 g/day of ITF | 9 weeks | Randomized controlled trial | UC | n = 12 7.5 g/day ITF and n = 13 15 g/day ITF | Roche 454 sequencing and GC—stool and mucosal biopsy samples | No significant clustering on PCA between treatment groups. Significant increase in stool Lachnospiraceae and Bifidobacteriaceae in high-dose ITF group. Significant reduction in mucosal Bacteroides and Parabacteroides in high-dose group. Significant increase in total SCFA and a trend towards an increase in butyrate in high-dose group. Butyrate was significantly inversely associated with Mayo score. | [59] |
CD—Chron’s disease, DF—dietary fiber, FISH—fluorescent in situ hybridization, FOS—fructo-oligosaccharide, GC—gas chromatography, IBD—inflammatory bowel disease, iSAD—improved standard American diet, LC-MS—liquid chromatography–mass spectrometry, LFD—low-fat, high-fiber diet, MES—mesalamine, OF-IN—oligofructose-enriched inulin, PCA—principal component analysis, PCR—polymerase chain reaction, POS—Plantago ovata seeds, rRNA—ribosomal ribonucleic acid SCFA—short-chain fatty acids, tds—three times daily, UC—ulcerative colitis.