Plain language summary
Irritable bowel syndrome (IBS) is a functional intestinal disorder that can significantly affect quality of life. IBS patients suffer from intermittent abdominal pain/ discomfort, altered bowel habits, and abdominal bloating/distension. The aim of this study was to assess the effects of dietary restriction and probiotic use on IBS‐D patients. This study was a 2 × 2 factorial design, single‐centre, randomised trial. Phase 1 was a 12‐week dietary intervention, with 214 participants randomised to an IgG positive restricted diet (IgG res diet) or a control diet (cold/spicy/fried restricted). In Phase 2, 167 participants were randomised into either an IgG res diet + placebo or an IgG res diet + probiotic for 12 weeks. Symptom Severity Scale (IBS‐D‐SSS) and IgG titer were assessed at the beginning and the end of the study. Results showed that both diets reduced IBS‐D symptom severity scores and decreased immunoglobulin (IgG) antibody titer, although the IgG res diet had a greater impact. IBS symptom scores decreased with the addition of a Bifidobacterium probiotic along with dietary exclusion, however, IgG titers did not change with the probiotic compared to placebo. Authors concluded that diet restriction with appropriate and effective probiotics, provides greater symptom reductions for patients with IBS-D.
Expert Review
Conflicts of interest:
None
Take Home Message:
For individuals with IBDS-D:
- Establish IgG intolerances to foods and ensure an elimination diet remains nutritionally balanced
- Consider combining elimination diet with a Bifidobacterium supplement.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
Irritable bowel syndrome (IBS) is a common functional intestinal disorder, affecting 5-20% of the population and diet is likely a major factor in its development as well as in its management. The aim of this study was to compare 3 dietary interventions and the use of a probiotic supplement in patients with IBS-diarrhoea dominant (IBS-D).
Methods
The study was conducted in 2 phases. The first was a 12-week 2 × 2 factorial design, randomised dietary intervention and included 224 patients (214 completed) with IBS-D. The diets were an Eastern/Chinese restriction diet, avoiding cold/raw, spicy and fried foods (CSF), the second avoided common allergens as determined by an IgG test (IgG diet, 14 foods tested), the third a combination of the two, whilst the control group continued their usual (Eastern/Chinese) diet.
The second phase was a 12-week randomised, double-blind, placebo-controlled trial comparing the CSF + IgG diet plus placebo with the CSF + IgG diet plus a 2 billion Bifidobacterium adolescentis supplement; this part included 202 patients of whom 169 completed the study.
The primary outcomes under observation were a reduction in IBS-D symptom severity Score (IBS-D-SSS) and IgG antibody titre (TigG).
Results
Phase 1: The IBS-D-SSS improved in all four groups from baseline (p<0.001), with the intervention groups improving significantly more than the control group (p<0.001). There was no statistically significant difference between the IgG and the IgG + CSF groups, although the authors considered there to be a synergistic effect. Statistically significant (p<0.001) reductions in TIgG were seen in all interventions, but not the control group.
Part 2: Significant (p<0.001) improvements in IBS-D-SSS were seen with both placebo and Bifidobacterium, although this was greater in the probiotic group (p<0.001). Improvements in TIgG were seen in both groups (p<0.001), with no difference between groups.
Conclusion
The authors concluded that the best intervention for patients with IBD-D is an IgG food elimination diet together with a Bifidobacterium probiotic supplement.
Clinical practice applications:
- Consider an elimination diet based on IgG testing for clients with IBS-D
- Consider combining elimination diet with a Bifidobacterium supplement. The dose used in this study was 4x 0.5 billion capsules of Bifidobacterium adolescentis
- Eliminating cold/raw, spicy and fried food could be an alternative to IgG elimination if the latter is not suitable for the client.
Considerations for future research:
- 45% and 35% of screened patients, respectively in the 2 phases of the study, were IgG negative. Screening for more potential food intolerances may extend the suitability of the approach to more patients
- Only a single strain probiotic was tested. Further research could evaluate other or combinations of Bifidobacteria strains in combination with an IgG elimination diet
- The mechanism(s) by which probiotics may affect symptoms of IBS-D are unknown. Adding stool microbiome analyses may shed further light on the effect of the intervention on the composition and function of the microbiome.
Abstract
BACKGROUND AND AIM Diet is a major contributor to irritable bowel syndrome (IBS) and is also a powerful tool for treatment of IBS. This study compared two diets and explored the effectiveness of the diets when combined with a probiotic for treatment of IBS-D patients. METHODS Phase I, patients were randomized into groups; control, cold/spicy/fried restricted diet (CSF res diet), IgG positive restricted diet (IgG res diet), and a combination both diets (CSF + IgG res diet). Phase II, patients were randomized into IgG res diet + placebo and IgG res diet + probiotic. Both interventions were 12 weeks in duration. Symptom Severity Scale (IBS-D-SSS) and IgG titer were assessed at the beginning and the end of the study. RESULTS Totals of 214 and 167 patients completed the two parts of the study, respectively. After intervention, IBS-D-SSS and TIgG grade were significantly improved compared to baseline, with results similar to the control group. In general, there were decreases in IBS-D-SSS and TIgG grade that were significantly different among the groups. There were exceptions; no differences were observed for IBS-D-SSS between the IgG res diet and CSF + IgG res diet, or TIgG grade between the CSF res diet, IgG res diet, and CSF + IgG res diet. However, the CSF res diet and IgG res diet had a synergistic effect that decreased IBS-D-SSS and TIgG titer, with a greater contribution by the IgG res diet. Therefore, we evaluated the IgG res diet with either placebo or probiotic and found that IBS-D-SSS and TIgG grade decreased from baseline. There was a significant decrease in IBS-D-SSS with the probiotic but TIgG grade was not significantly different between the IgG diet + placebo and IgG diet + probiotic diet. CONCLUSIONS Both the CSF res diet and IgG res diet improved IBS symptoms and demonstrated synergy, although the IgG res diet had a greater contribution. Further, when intolerant foods cannot be eliminated from a diet, avoiding uncooked, cold, spicy, fried, and alcoholic foods is a superior choice. The IgG res diet combined with Bifidobacteria was the best dietary choice and may function though a non-IgG pathway.
Methodological quality
Jadad score
:
3
Allocation concealment
:
Yes
