Randomised controlled trialindependent cross-checkabstract checked★ key study I-LEG-134 standard review
Which FODMAPs trigger IBS symptoms?
Efficacy and Findings of a Blinded Randomized Reintroduction Phase for the Low FODMAP Diet in Irritable Bowel Syndrome.
Overview
Van den Houte K et al.. Gastroenterology 2024 · PMID 38401741 · DOI 10.1053/j.gastro.2024.02.008
In blinded tests, the legume sugars (GOS) triggered symptoms in about a third of IBS patients, while fructans and mannitol were more common triggers.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Identify FODMAP triggers.
- How was the study done?
Blinded reintroduction.
- How many people, animals or samples were studied?
117 IBS patients.
- What was actually found?
Personal trigger patterns.
- How large was the observed effect?
GOS 35% vs control 26%.
- What do the results mean in everyday life?
Some people with IBS react to legumes; many do not.
- What are the study's limitations?
Tertiary care.
- What does it say about Elawady's specific claim?
Partly supports C-LEG-12.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
It does not apply to people without IBS.
Scientific in-depth review
1. Full reference
- Authors
- Van den Houte K et al.
- Journal
- Gastroenterology
- Year
- 2024
- Identifier
- PMID 38401741 DOI 10.1053/j.gastro.2024.02.008
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref works API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Not stated in abstract.
2. Research question
Which FODMAPs trigger symptoms in IBS patients who respond to a low-FODMAP diet?
3. Study design and population
- Study design
- Randomised controlled trial – Low-FODMAP elimination followed by blinded randomised reintroduction of six FODMAP powders vs glucose control
- Population
Tertiary-care IBS patients
- Country
Belgium (University Hospital Leuven)
- Period
6-week elimination, 9-week reintroduction
- Sample size
117 recruited
- Inclusion and exclusion criteria
Responders to 6-week low-FODMAP diet entered reintroduction.
4. Methods and endpoints
- Exposure / intervention
Fructans, fructose, GOS, lactose, mannitol, sorbitol powders
- Comparator
Glucose powder
- Endpoints
IBS-SSS rise >=50 points
- Statistical methods
Within-patient blinded challenges
5. Actual results
- Results
IBS-SSS improved from 301 to 150 after elimination (80% responders); triggers: fructans 56%, mannitol 54%, GOS 35%, lactose 28%, fructose 27%, sorbitol 23%, glucose 26%; average 2.5 triggers per patient.
- Absolute risks
Not applicable
- Authors' conclusion
Blinded reintroduction reveals a personalised trigger pattern, most often fructans and mannitol.
6. Strengths
- Blinded, randomised reintroduction with control powder
7. Weaknesses
- Tertiary-care population
- High 'control' response rate
- Abstract only
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Within-patient design; nocebo responses.
9. Assessment of the statistical interpretation
GOS excess over glucose control only about 9 percentage points (stats/C-LEG-12_reintroduction.py).
10. Relevance to the specific claim
Supports C-LEG-12 for a subset of IBS patients (legume GOS a trigger for about a third) and shows that triggers are individual, supporting reintroduction rather than permanent legume avoidance.
11. Independent contrary findings
None.
12. Transferability to Germany and Europe
Directly relevant.
13. Overall methodological judgement
Refines C-LEG-12: true for some IBS patients, individual.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | not replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Dose thresholds for legumes.
15. Linked fact checks
- Legumes (galacto-oligosaccharide/FODMAP sources) trigger bloating, pain and gas in people with irritable bowel syndrome; a low-FODMAP diet reduces symptoms. – Studies with mixed or unclear results