Predictive Value of Hydrogen/Methane Lactose Breath Testing on the Therapeutic Effect of Lactose-free Diet in Moderate to Severe ROME IV IBS.

  • End date
    Sep 1, 2024
  • participants needed
  • sponsor
    Universitair Ziekenhuis Brussel
Updated on 4 October 2022
abdominal pain
fatty acids
fodmap diet


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 fatty acids, carbon dioxide, H2 and methane (Catanzaro 2021). These compounds have an osmotic effect and can stimulate colonic contractions. These pathophysiological mechanisms encountered in patients suffering from LI generate symptoms, such as abdominal pain and cramps, flatulence, diarrhea, borborygmi among others. As dairy products are highly present in our Western diet, LI will often be considered in patients presenting with these symptoms and they will be referred for further testing. When LM is diagnosed, a lactose-free diet (LFD) will be advocated to alleviate symptoms. However, studies indicate that individuals with LM should tolerate up to 12 g of lactose when administered in a single dose (Suchy 2010).

Irritable bowel syndrome (IBS) is another frequently encountered disorder. According to the Rome IV criteria, it is characterized by abdominal pain associated with a change in stool frequency or consistency, or with symptomatic improvement by defecation (Mearin 2016). Associated symptoms, such as bloating and flatulence, are frequently reported. As such, discerning between IBS and LI based on symptoms alone can be challenging. Moreover lactose is considered part of the so-called fermentable oligo-, di-, monosaccharides and polyols (FODMAPs). A low FODMAP diet has been advocated for IBS with beneficial response in at least part of the patients (Halmos 2014).

Many studies investigated the role of lactose in IBS. These studies were performed in the pre-Rome IV era and before standardized interpretation rules for Hydrogen breath testing (H2BT) were published (meta-analysis by Varju 2019). This meta-analysis indicated that subjective LI was more frequently reported by IBS patients, but also objectively more prevalent in IBS patients, when assessed by any test modality. However, the role of a LFD in IBS remains uncertain.

This study aims to:

  • Determine if the diagnosis of LM by H2BT predicts the short-term and long-term response to a LFD in moderate to severe IBS as defined by Rome IV criteria;
  • Determine the changes in quality of life in response to a LFD in ROME IV IBS patients.

Condition Irritable Bowel Syndrome, Lactose Intolerant
Treatment Low fat diet
Clinical Study IdentifierNCT04974593
SponsorUniversitair Ziekenhuis Brussel
Last Modified on4 October 2022


Yes No Not Sure

Inclusion Criteria

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 or malabsorption
Known inflammatory bowel disorder
Known 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 mucoprotect-ants during the past 8 weeks
LFD or low FODMAP diet in the past
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