Protein MalabsorptionAgingGutNCT06553794
Protein Digestion and Amino Acid Absorption in the Aging Gastrointestinal Tract
A study testing Gastroscopy with duodenal mucosal tissue biopsies in people with Protein Malabsorption, run by Maastricht University Medical Center at 1 site in Netherlands.
Trial summary
Rationale: Worldwide, the aging population is increasing. Aging is associated with loss of independence and increased risk of co-morbidity. Sufficient protein intake is imperative to maintain skeletal muscle mass and overall health, and thereby stimulates active aging. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Protein Malabsorption
- What is being tested?
- Gastroscopy with duodenal mucosal tissue biopsies
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteNetherlands
- Study dates
- 20 Aug 2024to 13 Jun 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged 18-35 years or 67+ years
- Body mass index (BMI) between 18.5 and 30 kg/m2
- Regular stool frequency ranging from 1-3 times/day
Who cannot join
- History of cardiovascular, respiratory, gastrointestinal, urogenital, neurological, psychiatric, dermatologic, musculoskeletal, metabolic, endocrine, haematological, immunologic disorders, allergy, major surgery and/or laboratory assessments which might limit participation in or completion of the study protocol, interfere with the execution of the experiment, or potential influence the study outcomes (to be decided by the principal investigator and responsible physician)
- Major abdominal surgery interfering with gastrointestinal function (upon judgement of the principal investigator and responsible physician)
- Use of medication which limit participation in or completion of the study protocol, interferes with the execution of the experiment, or potential influences the study outcomes (to be decided by the principal investigator and responsible physician)
- Use of supplementation (i.e. protein, vitamin, pre- and probiotic supplementation) within 14 days prior to testing
- Administration of investigational drugs or participation in any scientific intervention study prior or during the study, which may interfere with this study (upon judgement of the principal investigator and responsible physician) Specific diet (e.g. vegetarian, vegan, gluten free, no diary) within the study period
- Planning to lose weight during the study period
Show all 13Show fewer
- Excessive alcohol consumption (defined as > 14 alcoholic consumptions per week)
- Smoking
- Drug use
- Pregnancy
- Lactation
- Donated blood three months prior to the test day
- No given permission to register participation in electronic patient file at MUMC+ and to add records of gastroduodenoscopy
Trial locations and contacts
1 site in 1 country.
About this study
Rationale: Worldwide, the aging population is increasing. Aging is associated with loss of independence and increased risk of co-morbidity. Sufficient protein intake is imperative to maintain skeletal muscle mass and overall health, and thereby stimulates active aging. It has been suggested that age-dependent changes in gastrointestinal (GI) tract physiology affect the amount of protein digested and absorbed, as well as the intestinal microbiota. However, it is not clear to what extent actual protein digestion and absorption are altered in older individuals. So far, no human data on the expression and activity of brush border enzymes and protein-related transporters in small intestinal epithelial cells are available. Understanding the age-dependent digestion and absorption kinetics of protein is important for creating specific diets in older individuals to improve protein intake and thereby stimulate healthy aging.
Objective: To assess the effects of aging on protein digestion and amino acid absorption in healthy humans in vivo.
Read more
Study design: Cross-sectional Study population: 12 healthy, non-obese (BMI 18.5-30kg/m2) young adults (age: 18-35 y inclusive) and 12 community dwelling older adults (age: ≥67 y).
Intervention: Subjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day"). Blood and saliva sampling will be conducted throughout the heavy water dosing protocol to determine body water and amino acid enrichment levels. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed to allow assessment of the expression and activity of brush border enzymes and protein-related transporters, and to determine fractional duodenal mucosal protein synthesis rate. Fecal samples will be collected at baseline and after the gastroscopy.
Main study parameters/endpoints: The primary study parameter is the mRNA expression of brush border enzymes and small peptide and amino acid transporters in duodenal mucosal cells. Secondary study parameters include protein expression of brush border enzymes and small peptide and amino acid transporters in duodenal mucosal cells, fecal microbial fermentation metabolites and duodenal mucosal protein synthesis rate.
Read the detailed description
Worldwide, the proportion of older individuals in the population is increasing. The progressive loss of skeletal muscle mass with aging, or sarcopenia, has a major impact on our health care system and costs due to increased morbidity and a greater need for hospitalization and/or institutionalization. A sufficient protein intake is imperative to maintain skeletal muscle mass and overall health, and thereby stimulates active aging. Whereas the overall protein intake is generally lower in older as compared to young adults, findings indicate that older adults need more protein to increase muscle protein synthesis, known as anabolic resistance. The exact mechanisms underlying anabolic resistance are not fully discovered yet. Age-dependent changes in gastrointestinal tract physiology have been suggested as a potential cause.
Following protein ingestion, protein is cleaved into small peptides and amino acids by digestive enzymes secreted in the stomach (pepsin) and small intestinal lumen (pancreatic trypsin, chymotrypsin, elastase), as well as brush border enzymes (aminopeptidase, carboxypeptidase, dipeptidase). Brush border enzymes are responsible for the final digestion of small peptides into dipeptides, tripeptides and amino acids. Subsequently, these small peptides and amino acids are absorbed across the intestinal mucosa by various membrane-bound transporters. The majority of dietary-protein derived amino acids is released into the systemic circulation and transported and taken up by various peripheral tissues in the postprandial phase.
It has been shown that postprandial plasma amino acid availability is lower in older compared to young adults. This indicates that digestion and absorption of proteins are likely attenuated in older individuals, thereby reducing the systemic availability of protein-derived amino acids for muscle protein synthesis and other relevant physiological processes.
Limited studies have focused on changes in gastrointestinal tract physiology with aging. Human studies on the expression and activity of brush border enzymes and protein transporters (i.e. for dipeptides, tripeptides and amino acids) being crucial for the final steps of digestion and absorption, respectively, are lacking. Therefore, the aim of the present study is to assess the expression and activity of brush border enzymes and expression of protein transporters in small intestinal epithelial cells in older as compared to young adults.
- Conditions
- Protein Malabsorption
- Being tested
- Gastroscopy with duodenal mucosal tissue biopsies
- Keywords
- Protein, Digestion, Absorption, Intestinal mucosa, Aging
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Gastroscopy with duodenal mucosal tissue biopsiesOther
Subjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day") and consume a standardized diet for 2 days. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed.
| Study group | Role | What they receive |
|---|---|---|
| Non-therapeutic intervention | Experimental | Subjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day") and consume a standardized diet for 2 days. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed. Receives: Other: Gastroscopy with duodenal mucosal tissue biopsies |
What is being measured
The primary outcome is the main question the study is designed to answer.
Gene expression of brush border enzymes and protein-related transporters in duodenal mucosal cells
as determined by real-time polymerase chain reaction (PCR)
Measured: day 3 of study period
Secondary outcomes (5)
Protein expression of brush border enzymes and protein-related transporters
as determined by proteomic analysis
Measured: day 3 of study period
Microbial proteolytic fermentation metabolites involved in protein metabolism
as determined by high performance liquid chromatography-mass spectrometry
Measured: Baseline
Fractional duodenal mucosal protein synthetic rate
as determined using stable isotope tracer methodology (D2O)
Measured: during study period (3 days)
Fecal elastase
as marker for pancreatic enzyme secretion
Measured: Baseline
Plasma citrulline
as a marker for total functional enterocyte mass
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Aug 2024
- Study start20 Aug 2024
- Primary completion13 Jun 2025
- Study completion13 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Protein MalabsorptionStudies of the same condition, open and under way.
- More trials run by Maastricht University Medical CenterThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 24 participants (actual)
Sponsor and investigators
- Lead sponsor
- Maastricht University Medical Center
- Sponsor type
- University, hospital or other
- Collaborators
- FrieslandCampina
- Responsible party
- Sponsor
- Investigators
- Daisy Jonkers, Prof, Principal investigator, Maastricht University Medical CenterLuc van Loon, Prof, Principal investigator, Maastricht University Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06553794
- Sponsor's protocol ID
- METC23-029
- Acronym
- AgingGut
- Status last verified
- Sep 2025
- First submitted
- 27 Jun 2023
- Last updated
- 15 Sep 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 15 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Protein Digestion and Amino Acid Absorption in the Aging Gastrointestinal Tract
- ClinicalTrials.gov ID
- NCT06553794
- Acronym / sponsor ID
- AgingGut / METC23-029
- Conditions
- Protein Malabsorption
- Keywords
- Protein, Digestion, Absorption, Intestinal mucosa, Aging
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 24 participants (actual)
- Lead sponsor
- Maastricht University Medical CenterUniversity, hospital or other
- Collaborators
- FrieslandCampina
- Study start
- 20 Aug 2024 (actual)
- Primary completion
- 13 Jun 2025 (actual)
- Study completion
- 13 Jun 2025 (actual)
- First posted
- 14 Aug 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Rationale: Worldwide, the aging population is increasing. Aging is associated with loss of independence and increased risk of co-morbidity. Sufficient protein intake is imperative to maintain skeletal muscle mass and overall health, and thereby stimulates active aging. It has been suggested that age-dependent changes in gastrointestinal (GI) tract physiology affect the amount of protein digested and absorbed, as well as the intestinal microbiota. However, it is not clear to what extent actual protein digestion and absorption are altered in older individuals. So far, no human data on the expression and activity of brush border enzymes and protein-related transporters in small intestinal epithelial cells are available. Understanding the age-dependent digestion and absorption kinetics of protein is important for creating specific diets in older individuals to improve protein intake and thereby stimulate healthy aging.
Objective: To assess the effects of aging on protein digestion and amino acid absorption in healthy humans in vivo.
Study design: Cross-sectional Study population: 12 healthy, non-obese (BMI 18.5-30kg/m2) young adults (age: 18-35 y inclusive) and 12 community dwelling older adults (age: ≥67 y).
Intervention: Subjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day"). Blood and saliva sampling will be conducted throughout the heavy water dosing protocol to determine body water and amino acid enrichment levels. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed to allow assessment of the expression and activity of brush border enzymes and protein-related transporters, and to determine fractional duodenal mucosal protein synthesis rate. Fecal samples will be collected at baseline and after the gastroscopy.
Main study parameters/endpoints: The primary study parameter is the mRNA expression of brush border enzymes and small peptide and amino acid transporters in duodenal mucosal cells. Secondary study parameters include protein expression of brush border enzymes and small peptide and amino acid transporters in duodenal mucosal cells, fecal microbial fermentation metabolites and duodenal mucosal protein synthesis rate.
Detailed description
Worldwide, the proportion of older individuals in the population is increasing. The progressive loss of skeletal muscle mass with aging, or sarcopenia, has a major impact on our health care system and costs due to increased morbidity and a greater need for hospitalization and/or institutionalization. A sufficient protein intake is imperative to maintain skeletal muscle mass and overall health, and thereby stimulates active aging. Whereas the overall protein intake is generally lower in older as compared to young adults, findings indicate that older adults need more protein to increase muscle protein synthesis, known as anabolic resistance. The exact mechanisms underlying anabolic resistance are not fully discovered yet. Age-dependent changes in gastrointestinal tract physiology have been suggested as a potential cause.
Following protein ingestion, protein is cleaved into small peptides and amino acids by digestive enzymes secreted in the stomach (pepsin) and small intestinal lumen (pancreatic trypsin, chymotrypsin, elastase), as well as brush border enzymes (aminopeptidase, carboxypeptidase, dipeptidase). Brush border enzymes are responsible for the final digestion of small peptides into dipeptides, tripeptides and amino acids. Subsequently, these small peptides and amino acids are absorbed across the intestinal mucosa by various membrane-bound transporters. The majority of dietary-protein derived amino acids is released into the systemic circulation and transported and taken up by various peripheral tissues in the postprandial phase.
It has been shown that postprandial plasma amino acid availability is lower in older compared to young adults. This indicates that digestion and absorption of proteins are likely attenuated in older individuals, thereby reducing the systemic availability of protein-derived amino acids for muscle protein synthesis and other relevant physiological processes.
Limited studies have focused on changes in gastrointestinal tract physiology with aging. Human studies on the expression and activity of brush border enzymes and protein transporters (i.e. for dipeptides, tripeptides and amino acids) being crucial for the final steps of digestion and absorption, respectively, are lacking. Therefore, the aim of the present study is to assess the expression and activity of brush border enzymes and expression of protein transporters in small intestinal epithelial cells in older as compared to young adults.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Non-therapeutic intervention | Experimental | Other: Gastroscopy with duodenal mucosal tissue biopsiesSubjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day") and consume a standardized diet for 2 days. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Aged 18-35 years or 67+ years
- Body mass index (BMI) between 18.5 and 30 kg/m2
- Regular stool frequency ranging from 1-3 times/day
Key exclusion criteria (13 listed)
- History of cardiovascular, respiratory, gastrointestinal, urogenital, neurological, psychiatric, dermatologic, musculoskeletal, metabolic, endocrine, haematological, immunologic disorders, allergy, major surgery and/or laboratory assessments which might limit participation in or completion of the study protocol, interfere with the execution of the experiment, or potential influence the study outcomes (to be decided by the principal investigator and responsible physician)
- Major abdominal surgery interfering with gastrointestinal function (upon judgement of the principal investigator and responsible physician)
- Use of medication which limit participation in or completion of the study protocol, interferes with the execution of the experiment, or potential influences the study outcomes (to be decided by the principal investigator and responsible physician)
- Use of supplementation (i.e. protein, vitamin, pre- and probiotic supplementation) within 14 days prior to testing
- Administration of investigational drugs or participation in any scientific intervention study prior or during the study, which may interfere with this study (upon judgement of the principal investigator and responsible physician) Specific diet (e.g. vegetarian, vegan, gluten free, no diary) within the study period
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Gastroscopy with duodenal mucosal tissue biopsiesSubjects will undergo a standardized heavy water dosing protocol for 2 days (1 "loading day", 1 "maintenance day") and consume a standardized diet for 2 days. On the experimental test day, a gastroscopy with collection of duodenal mucosa tissue samples will be performed. | Other | Non-therapeutic intervention |
Primary outcome
Gene expression of brush border enzymes and protein-related transporters in duodenal mucosal cells
Time frame: day 3 of study period
as determined by real-time polymerase chain reaction (PCR)
5 secondary outcomes
Protein expression of brush border enzymes and protein-related transporters
Time frame: day 3 of study period
Microbial proteolytic fermentation metabolites involved in protein metabolism
Time frame: Baseline
Fractional duodenal mucosal protein synthetic rate
Time frame: during study period (3 days)
Fecal elastase
Time frame: Baseline
Plasma citrulline
Time frame: Baseline
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Sep 2025.
- Individual participant dataSharing planned: No
Related trials for Protein Malabsorption
Recruiting
Achieving nuTritional Target in criticAlly Ill patieNts With iMpairEd gastroiNtesTinal Dysfunction
Parenteral Nutrition, Gastroparesis
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Daisy Jonkers, Prof principal investigator
Maastricht University Medical Center
Luc van Loon, Prof principal investigator
Maastricht University Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Gastroscopy with duodenal mucosal tissue biopsies in people with Protein Malabsorption, run by Maastricht University Medical Center at 1 site in Netherlands.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Gene expression of brush border enzymes and protein-related transporters in duodenal mucosal cells (time frame: day 3 of study period). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Sep 2025; AzTrials last refreshed its copy on 8 Nov 2026.