Table 2.
Interventions and outcomes of the included randomized controlled trials investigating low FODMAP diet in patients with IBD and FGS.
| First Author: | Bodini [26] | Cox [24,25] | Halmos [23] | Pedersen [27,28,29] |
|---|---|---|---|---|
| Relief assessment: | NR | GSQ | 100 mm VAS | NR |
| Improvement definition: | NR | Achieving a 50-point reduction in IBS-SSS | NR | Achieving a 50-point reduction in IBS-SSS |
| Intervention: | LFD No ONS was allowed |
LFD | LFD ≤ 0.5 g per sitting [37] (three main meals and three snacks daily were delivered to patients) + small quantities of psyllium and resistant starch (daily average of 3 g psyllium and 5 g Hi-Maize 220 (National Starch and Chemical Company, Bridgewater, NJ, USA), to ensure similar fiber content | LFD |
| Comparator: | Standard diet | Sham exclusion diet of similar intensity, burden, and nutrient intake to the LFD | typical Australian diet | Normal diet |
| Assessment of dietary FODMAP intake: | Detailed meals with calculated FODMAP content (NOD) | Via FODMAP database (Monash University, Melbourne, Australia) | FODMAP content for all provided food underwent FODMAP analysis via high-performance liquid chromatography and enzymatic assays | NR |
| Intervention duration: | 6 weeks | 4 weeks | 21 days (each intervention) | 6 weeks |
| Wash-out duration: | N/A | N/A | >21 days (until the symptoms had returned to the same level as during their habitual diet) | N/A |
| Stool: | Sample | 7-day diary and fresh stool sample at baseline | 5-day samples | Sample |
| fCAL assay: | Quantum Blue fCAL (Buhlmann Lab) | ELISA | ELISA using a commercial kit (Buhlmann EK-Cal, Schönenbuch, Switzerland) | Home-administered collecting kit and ELISA |
| Compliance assessment: | Dietitian (weekly phone calls and food diaries) | With a question at the end of the trial: “During the 4-week trial I have followed the diet…”: never/rarely (<25% of the time), sometimes (25–50% of the time), frequently (51–75% of the time) or always (76–100% of the time) and with 7-day food diaries | Dietitian | FFQ [45] with the most commonly consumed high-FODMAP foods adapted to the Danish population |
| Dropouts (n): | - |
n = 6 (2 withdrew consent, 1 became pregnant, 1 initiated steroids, and 1 antibiotics) n = 3 for low compliance |
n = 1 for low LFD compliance | n = 11 (7 for difficulty in LFD compliance and 4 for lack of compliance with registering IBS symptoms) |
| Non-compliant (n): | NR | n = 3 | n = 1 from the LFD group | n = 7 from the LFD group |
| Adverse events (n): | NR |
n = 2 IBD relapse (one in each group) n = 1 started antibiotics unrelated to IBD n = 1 abdominal pain (controls) n = 2 flu-like symptoms and sinusitis (one in each group) |
NR | |
| Primary outcomes: | Δ in PMS, HBi, IBD-Q |
Δ in IBS-SSS | Δ in fecal microbiota including total, butyrate-producing (C. leptum, F. prausnitzii, Roseburia spp.), traditionally prebiotic (Lactobacilli and Bifidobacteria spp.), and mucus-degrading bacteria (A. muciniphila, R. gnavus, R. torques) | Δ in HBi, SCCAI, patients reporting improvement |
| Secondary outcomes: | Δ in CRP levels, fCAL, anthropometry | Δ in GSRS, fecal SCFA (GLC), fecal pH (InLab, Mettler Toledo probe), CRP, BSFS, IBD-Q, HBi, PMS, IBD Control Q, fecal microbiome composition and function | fecal pH, total and specific fecal SCFA concentration, severity of GI symptoms (100 mm VAS), fecal frequency and weight, FWC, whole-gut transit time, comparison of data during interventional diets to habitual diet | Δ in IBS-SSS, QoL (HR-QoL, IBS-QoL), CRP, fCAL, SIBDQ, SF36, treatment satisfaction (VAS) |
| Microbiome composition: | - | Via quantitative metagenomic pipeline | PCR on DNA fecal samples | - |
| T-cell phenotype: | - | CD3, CD45RA+, CD45RA-, CD4, CD8, Vδ2 unconventional T-cells, integrin α4β7 | - | - |
| Timepoints: | Baseline and end (6 weeks) | Baseline and end of trial (4 weeks) | Start and end of each intervention | Baseline and 6 weeks |
| Analyses: | ITT n = 55 | ITT n = 52 PP n = 43 |
PP n = 8 | ITT intervention n = 37 ITT controls n = 41 |
| Jadad score [22]: | 3 | 3 | 3 | 2 |
A. muciniphila, Akkermansia muciniphila; B. adolescentis, Bifidobacterium adolescentis; B. longum, Bifidobacterium longum; BSFS, Bristol Stool Form Scale [41]; CRP, C-reactive protein; ELISA, enzyme-linked immunosorbent assay; fCAL, fecal calprotectin; FFQ, food frequency questionnaire; F. prausnitzii, Faecalibacterium prausnitzii; FGS, Functional gastrointestinal symptoms; FODMAP, Fermentable Oligo-, Di-, Monosaccharides, and Polyols; FWC, fecal water content; GI, gastrointestinal; GLC, gas–liquid chromatography; GSRS, Gastrointestinal symptoms rating scale [46]; GSQ, Global Symptom Question [47,48]; HBi, Harvey Bradshaw Index for CD [33]; HR-QoL, IBS Health-related Quality of Life [43]; IBD, inflammatory bowel diseases; IBD-Q, inflammatory bowel disease—Quality of Life [34,35]; IBD-Control-Q, IBD Control Questionnaire [38]; IBS, irritable bowel syndrome; IBS-QoL, IBS Quality of Life [44]; IBS-SSS, IBS Severity Scoring System [49]; ITT, intention to treat; LFD, Low FODMAP diet; N/A, not applicable; NOD, not other defined; NR, not reported; ONS, oral nutrient supplements; PCR, polymerase chain reaction; PMS, Partial Mayo Score for UC [36]; PP, per protocol; R. gnavus, Ruminococcus gnavus; R. torques, Ruminococcus torques; SCCAI, Simple clinical colitis activity index [39]; SCFA, short-chain fatty acids; SIBDQ, Short Inflammatory Bowel Disease Questionnaire; SF36, Short-form 36 [42]; VAS, Visual analogue scale.