Help guide our efforts to modernize
Send us your comments by March 14, 2020. Menu

Comparison of the Colonic Metabolism in Patients With Lactose Intolerance and Healthy Controls

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02171403
Recruitment Status : Completed
First Posted : June 24, 2014
Last Update Posted : July 29, 2015
Information provided by (Responsible Party):
Kristin Verbeke, KU Leuven

Brief Summary:

Most people are born with the ability to digest lactose, a dissacharide consisting of β-D-glucose and β-D-galactose, because of the presence of lactase at the brush border of the small intestine. In about 75% of the world population the activity of this enzyme decreases after weaning (primary hypolactasia or lactase-nonpersistence), resulting in incomplete digestion of lactose and lactose malabsorption in adulthood (1). Secondary forms of lactose malabsorption may be due to inflammation or functional loss of the intestinal mucosa such as celiac disease, infectious enteritis or Crohn's disease. Very rarely, lactase deficiency is congenital due to an autosomal recessive genetic disorder, preventing lactase expression from birth (2). Whereas some people with lactose malabsorption are asymptomatic, most lactose-nonpersisters experience symptoms like abdominal pain, bloating, excess flatulence or diarrhea. Lactose intolerance refers to the syndrome of having one or more symptoms after consumption of lactose-containing food (3). At present, the origin of the symptoms of lactose-intolerance is not well understood.

Several studies have indicated a poor correlation between lactose maldigestion and symptoms of lactose intolerance (4). In a study by Vonk et al. (2003), lactose intolerant subjects with severe symptoms (diarrhea) and intolerant subjects with only mild symptoms (without diarrhea) did not differ in degree of lactose digestion in the small intestine indicating a similar lactase activity and leading them to the hypothesis of a "colon resistence factor" (5). It was suggested that the colonic processing of maldigested lactose may play a role in the symptoms experienced by lactose intolerant patients. When lactose is malabsorbed and enters the colon, it is rapidly fermented by the resident microbiota into a variety of metabolites including lactate, formate, succinate and short chain fatty acids (SCFA, acetate, propionate, butyrate) as well as gases (H2, CO2 and CH4). When incubating fecal samples from lactose-tolerant and intolerant subjects with lactose, the samples from the lactose-intolerant subjects showed faster production rates of D- and L-lactate, acetate, propionate and butyrate, as compared to tolerant subjects (6). Although the colon is thought to possess a high capacity to absorb SCFA, it was hypothesized that a temporary accumulation of these metabolites due to rapid fermentation of maldigested lactose could be responsible for abdominal pain, excess flatulence and bloating (7;8). Possible mechanisms proposed to explain how SCFA might induce symptoms included an increase in the osmotic load that draws fluid to the colonic lumen, changes in colonic motility and an increased colonic sensitivity (9-11). However, the calculated amount of fluid drawn in the colon is unlikely to cause symptoms considering the high water absorbing capacity of the colon and the effect of SCFA on colonic motility and colonic sensitivity have only been observed in rats and not in humans.

More recently, Campbell et al. introduced the bacterial metabolic toxin hypothesis, stating that also other bacterial metabolites, such as alcohols, aldehydes, acids and ketones, resulting from carbohydrate fermentation play a role in the pathogenesis of lactose-intolerance. These metabolites might inhibit bacterial growth and affect eukaryotic cells (12). In our own previous studies in which we related colonic fermentation patterns to parameters of cytotoxicity, we identified compounds like propionic acid, medium chain fatty acids, 1-octanol and heptanal as more prevalent in the most cytotoxic samples (13), supporting the hypothesis of Campbell et al. Therefore, it seems necessary to include not only SCFA, but also other metabolites, in the investigation of the pathogenesis of lactose intolerance.

Differences in fermentation patterns might be associated with differences in the composition and/or activity of the intestinal microbiota. Evidence on the potential role of the colonic microbiota in lactose intolerance is very limited. Total bacterial numbers were not significantly different between 16 intolerant and 11 tolerant lactose maldigesters although a negative correlation between total bacteria and symptom score was found (14). Similarly, the composition of fecal microbiota was not different between 5 intolerant and 7 tolerant subjects (6).

Condition or disease
Lactose Intolerance

Detailed Description:
In this study we will compare colonic fermentation and parameters of gut health (fecal water cytotoxicity) between patients who are lactose intolerant, patients who have lactose malabsorption and healthy subjects.

Layout table for study information
Study Type : Observational
Actual Enrollment : 34 participants
Observational Model: Case Control
Time Perspective: Prospective
Official Title: Comparison of the Colonic Metabolism in Patients With Lactose Intolerance and Healthy Controls
Study Start Date : June 2014
Actual Primary Completion Date : March 2015
Actual Study Completion Date : March 2015

Resource links provided by the National Library of Medicine

Lactose intolerance
Patients with a positive lactose-breath test and complaints during the test
Lactose malabsorption
Patients with a positive lactose-breath test and no complaints during the test
Healthy controls
Subjects with a negative lactose-breath test

Primary Outcome Measures :
  1. fecal water genotoxicity [ Time Frame: 1 day ]
    Fecal water, prepared by ultracentrifugation of fecal samples, will be incubated with HT-29 cells, a colonic adenocarcinoma cell line. Fecal water genotoxicity will be assessed using the Comet Assay, a sensitive method to detect DNA damage at the level of the individual eukaryotic cell. During the Comet Assay, the cells undergo electrophoresis causing movement of the damaged DNA out of the nucleus. The amount of DNA damage will be determined by measuring the extent the DNA has moved out of the nucleus, using fluorescent microcropy and dedicated software.

Secondary Outcome Measures :
  1. fecal water cytotoxicity [ Time Frame: 1 day ]
    Fecal water cytotoxicity will be measured using the WST-1 assay, a colorimetric test based on the conversion of the tetrazolium salt WST-1 by cellular mitochondrial dehydrogenases present in viable cells. The dilution of fecal water at which 50% of the cells survive will be determined. The higher the dilution, the more cytotoxic the sample is.

Biospecimen Retention:   Samples Without DNA
Fecal samples

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
Patients with a positive test (reduced lactose digestion and increased H2-excretion) and complaints will be included in the group of lactose-intolerant patients and patients with a positive result without complaints will be included in the group of lactose-malabsorption patients. Subjects with a normal breath test will be recruited as controls.

Inclusion Criteria:

  • healthy or positive lactose breath test
  • > 18 Year
  • 18 kg/m²<BMI<27.5 kg/m²
  • regular dietary pattern

Exclusion Criteria:

  • intake of antibiotics 1 month prior to sample collection
  • abdominal chirurgical intervention except appendectomy
  • intake of medication 14 days prior to sample collection
  • vegetarian
  • intake of pre- or probiotics

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02171403

Layout table for location information
Leuven, Vlaams-Brabant, Belgium, 3000
Sponsors and Collaborators
KU Leuven
Layout table for investigator information
Principal Investigator: Kristin Verbeke, Professor KU Leuven

Layout table for additonal information
Responsible Party: Kristin Verbeke, Professor Kristin Verbeke, KU Leuven Identifier: NCT02171403    
Other Study ID Numbers: B322201421130
ML10399 ( Other Identifier: UZ Leuven ethical committee )
First Posted: June 24, 2014    Key Record Dates
Last Update Posted: July 29, 2015
Last Verified: July 2015
Additional relevant MeSH terms:
Layout table for MeSH terms
Lactose Intolerance
Malabsorption Syndromes
Intestinal Diseases
Gastrointestinal Diseases
Digestive System Diseases
Carbohydrate Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn
Metabolic Diseases