Efficacy of a Low FODMAP Diet in the Absence of Lactose Malabsorption in Moderate to Severe ROME IV IBS.

  • End date
    Sep 23, 2024
  • participants needed
  • sponsor
    Universitair Ziekenhuis Brussel
Updated on 4 October 2022
abdominal pain
fodmap diet


Irritable bowel syndrome (IBS) is a frequently encountered disorder. According to the Rome IV criteria, it is characterized by abdominal pain associated with a change in stool frequency or con-sistency, or with symptomatic improvement by defecation (Mearin 2016). Associated symptoms, such as bloating and flatulence, are frequently reported. The underlying pathophysiology remains obscure, although several pathways have been proposed. Low-grade immune activation, visceral hypersensitivity, alteration in gut microbiome have all been reported (Mearin 2016). As diet exerts an impact on all these pathophysiological mechanisms, the role of dietary intervention receives spe-cial attention, with special interest in the role played by so-called fermentable oligo-, di-, monosac-charides and polyols (FODMAPs). Multiple studies indicated the beneficial effects of the low FODMAP diet in at least part of the patients (Halmos 2014, Eswaran 2016, Staudacher 2017).

As a disaccharide, lactose is part of the FODMAPs. Lactose intolerance (LI) results from lactose malabsorption (LM) secondary to insufficient hydrolysis of the disaccharide lactose into galactose and glucose (Misselwitz 2019). The undigested lactose will eventually reach the colon, resulting in fermentation from colonic bacteria with production of different compounds such as short chain fat-ty acids, carbon dioxide, H2 and methane (Catanzaro 2021). These compounds have an osmotic effect and can stimulate colonic contractions. In patients suffering from LI, these pathophysiologi-cal mechanisms generate symptoms such as abdominal pain and cramps, flatulence, diarrhea, in-creased bowel sounds, among others, similar to the mechanisms by which FODMAPs induce symp-toms of IBS. As dairy products are highly present in our Western diet, LI will often be considered in patients presenting with such symptoms and they will be referred for further testing. When LM is diagnosed, a lactose-free diet (LFD) will be advocated to alleviate symptoms.

While the earlier-mentioned studies investigated symptomatic improvement by the low FODMAP diet, it remains uncertain whether this restrictive diet remains beneficial in patients without evidence of LM. In a recent study the low FODMAP diet and LFD provided comparable improvement in symptom severity (Krieger-Grbel 2020).

This study aims to:

  • Assess the improvement in IBS symptoms and quality of life (QOL) by a low FODMAP di-et when lactose malabsorption has been previously excluded;
  • Compare the improvement in IBS symptoms and QOL obtained by a low FODMAP diet to a lactose free diet (data from the PreVaIL study).

Condition Irritable Bowel Syndrome (IBS- Pediatric), Irritable Bowel Syndrome (IBS), Irritable Bowel Syndrome
Treatment FODMAP diet
Clinical Study IdentifierNCT05120752
SponsorUniversitair Ziekenhuis Brussel
Last Modified on4 October 2022


Yes No Not Sure

Inclusion Criteria

\- Patients aged 18 - 75 years
Fulfilling the ROME IV criteria for IBS
Moderate symptom severity as defined by a IBS-SSS > 175
Consumption of lactose containing products

Exclusion Criteria

\- Clinical suspicion of an organic disorder different from LI or IBS (patients can be included when this disorder had been excluded)
Known lactose intolerance
Known inflammatory bowel disorder
Known major intestinal motility disorder
Alcohol (defined as more than 14 U per week) or other substance abuse
Active psychiatric disorder
Known systemic or auto-immune disorder with implication for the GI system
Prior abdominal surgery (with the exception of appendectomy)
Any prior diagnosis of cancer other than basocellular carcinoma
Current chemotherapy
History of gastro-enteritis in the past 8 weeks
Intake of antibiotics, pre- or probiotics during the past 8 weeks
Dietary supplements unless taken at a stable dose for more than 8 weeks
Treatment with neuromodulators (one neuromodulator taken at a stable dose for more than 12 weeks is allowed)
Treatment with spasmolytic agents, opioids, loperamide, gelatin tannate or mucoprotectants during the past 8 weeks
LFD or low FODMAP diet in the past
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