Protein MetabolismNCT05400733
Prandial Metabolic Phenotype in Adults
A study testing Total Amino Acids, Essential Amino Acids and Essential Amino Acids + Hydroxy-methylbutyric acid (HMB) in people with Protein Metabolism, run by Texas A&M University at 1 site in United States.
Trial summary
Previous studies suggest that changes in metabolism due to the effects of aging might serve as a potential for therapeutic agents. The investigating lab developed a pulse method combining multiple stable isotopes to study multiple metabolic pathways in the same individual simultaneously. Read more about this study
- Who is it for?
- Ages 60 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- Protein Metabolism
- What is being tested?
- Total Amino Acids, Essential Amino Acids and Essential Amino Acids + Hydroxy-methylbutyric acid (HMB)
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 38 participants
- Where
- 1 siteUnited States
- Study dates
- 24 Jun 2022to Sep 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 60 to 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Age: 60-80, inclusive
- Stable body-weight (± 5%) for the past 3 months
- Subject is judged to be in satisfactory health based on medical history, physical examination, and laboratory screening evaluations.
- Ability to walk, sit down and stand up independently or with walking mobility aids
- Ability to lie in supine or elevated position for up to 7 hours
- Willingness and ability to comply with the protocol
Who cannot join
- Established diagnosis of current malignancy
- History of untreated metabolic diseases including hepatic or renal disorder
- Presence of acute illness or metabolically unstable chronic illness
- Presence of fever within the last 3 days
- Use of short course of oral corticosteroids within 4 weeks preceding study day
- (Possible) pregnancy
Show all 9Show fewer
- Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
- Already enrolled in another clinical trial and that clinical trial interferes with participating in this study
- Any other condition according to the PI or nurse that was found during the screening visit, that would interfere with the study or safety of the patient
Trial locations and contacts
1 site in 1 country.
United States1 site
Human Clinical Research Facility
College Station, Texas, 77843
About this study
Previous studies suggest that changes in metabolism due to the effects of aging might serve as a potential for therapeutic agents. The investigating lab developed a pulse method combining multiple stable isotopes to study multiple metabolic pathways in the same individual simultaneously. By measuring whole-body metabolism in a large group of older adults, the investigators may be able to unravel age-related deterioration in protein turnover (synthesis and breakdown) that contributes to impaired functional capacity. Metabolic profiles could explain differences in pathways in the aging process with special interest in metabolism of amino acids as they have been associated with aging-related disorders.
Read the detailed description
The study involves 1 screening visits of approximately 3 hours and 6 study days of approximately 8 hours.
Subjects will be asked to arrive in the fasted state on all study days. Fasting prior to screening is not required. On the screening day, body weight, height, and body composition by Dual-energy X-ray absorptiometry (DXA) will be measured. In addition, The Six-Minute Walk Test (6MWT) and skeletal muscle function tests will be assessed at the end of each screening visit.
Each study visit will begin with vital signs. Before administration of the feeding or the tracer solution, baseline blood will be collected for measurement of the natural enrichment of metabolites. After the baseline sample is collected, feeding will begin and will be followed by tracers of several compounds that may be administered by IV pulse.
Next, the subjects will be fed one of six liquid nutritional supplement every 20 minutes for 6 hours. The liquid nutrition supplement will target the amino acid formulation in the following meals (1) total amino acid, (2) Essential Amino Acids (EAA), (3) EAA + -hydroxy -methylbutyric acid (HMB), (4) EAA + leucine (LEU), (5) EAA high, and (6) Placebo.
- Conditions
- Protein Metabolism
- Being tested
- Total Amino Acids, Essential Amino Acids, Essential Amino Acids + Hydroxy-methylbutyric acid (HMB), Essential Amino Acids + Leucine, Essential Amino Acids High
- Keywords
- prandial
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Total Amino AcidsDietary supplement
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Alanine, Arginine, Aspartate, Cystine, Glutamine, Glutamate, Glycine, Proline, Serine, Tyrosine. All supplements are commercially available.
Essential Amino AcidsDietary supplement
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine. All supplements are commercially available.
Essential Amino Acids + Hydroxy-methylbutyric acid (HMB)Dietary supplement
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, HMB. All supplements are commercially available.
Essential Amino Acids + LeucineDietary supplement
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Extra leucine. All supplements are commercially available.
Essential Amino Acids HighDietary supplement
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine. All supplements are commercially available.
Placebo WaterDietary supplement
Water
| Study group | Role | What they receive |
|---|---|---|
| Healthy male older adults | Other | Healthy male older adults Receives: Dietary Supplement: Total Amino Acids; Dietary Supplement: Essential Amino Acids; Dietary Supplement: Essential Amino Acids + Hydroxy-methylbutyric acid (HMB); Dietary Supplement: Essential Amino Acids + Leucine; Dietary Supplement: Essential Amino Acids High; Dietary Supplement: Placebo Water |
| Healthy female older adults | Other | Healthy female older adults Receives: Dietary Supplement: Total Amino Acids; Dietary Supplement: Essential Amino Acids; Dietary Supplement: Essential Amino Acids + Hydroxy-methylbutyric acid (HMB); Dietary Supplement: Essential Amino Acids + Leucine; Dietary Supplement: Essential Amino Acids High; Dietary Supplement: Placebo Water |
What is being measured
The primary outcome is the main question the study is designed to answer.
Feeding related changes in whole-body protein and amino acid metabolism
Whole-body production rate measured after stable tracer administration
Measured: up to 6 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jun 2022
- Study start24 Jun 2022
- Primary completionSep 2027 (estimated)
- Study completionSep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Protein MetabolismStudies of the same condition, open and under way.
- 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
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 38 participants (actual)
Sponsor and investigators
- Lead sponsor
- Texas A&M University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Marielle PKJ Engelen, PhD, Texas A&M University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05400733
- Sponsor's protocol ID
- 83 - Pulse Feeding
- Status last verified
- Sep 2026
- First submitted
- 27 May 2022
- Last updated
- 5 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Data may be shared upon request for up to 6 years beyond completion of the trial based on methods/proposal approved by both parties' institutional review committees. Individual participant data that underlie the results of the trial may be shared after de-identification (text, tables, figures, and appendices). Additional documents available per request include: study protocol, statistical analysis plan, and informed consent. Requests should be directed to Dr. Marielle Engelen (mpkj.engelen@ctral.org).
Publications
Knezek SB, Engelen MPKJ, Coyle KS, Perez CN, Deutz NEP. Adding free leucine to a balanced essential amino acid mixture suppresses intracellular transamination of isoleucine and valine in healthy older adults. Clin Nutr. 2026 Jun;61:106659. doi: 10.1016/j.clnu.2026.106659. Epub 2026 Apr 9.
PubMed 42013668Deutz NEP, Knezek SB, Engelen MPKJ. A novel pulse tracer method to estimate the relationship between amino acid meal composition and its intracellular disposal. Clin Nutr. 2025 Dec;55:196-207. doi: 10.1016/j.clnu.2025.10.002. Epub 2025 Oct 22.
PubMed 41260190
Study at a glance
From the registry record, last updated by the sponsor on 5 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prandial Metabolic Phenotype in Adults
- ClinicalTrials.gov ID
- NCT05400733
- Acronym / sponsor ID
- 83 - Pulse Feeding
- Conditions
- Protein Metabolism
- Keywords
- prandial
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 38 participants (actual)
- Lead sponsor
- Texas A&M UniversityUniversity, hospital or other
- Study start
- 24 Jun 2022 (actual)
- Primary completion
- Sep 2027 (estimated)
- Study completion
- Sep 2027 (estimated)
- First posted
- 2 Jun 2022 (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.
Previous studies suggest that changes in metabolism due to the effects of aging might serve as a potential for therapeutic agents. The investigating lab developed a pulse method combining multiple stable isotopes to study multiple metabolic pathways in the same individual simultaneously. By measuring whole-body metabolism in a large group of older adults, the investigators may be able to unravel age-related deterioration in protein turnover (synthesis and breakdown) that contributes to impaired functional capacity. Metabolic profiles could explain differences in pathways in the aging process with special interest in metabolism of amino acids as they have been associated with aging-related disorders.
Detailed description
The study involves 1 screening visits of approximately 3 hours and 6 study days of approximately 8 hours.
Subjects will be asked to arrive in the fasted state on all study days. Fasting prior to screening is not required. On the screening day, body weight, height, and body composition by Dual-energy X-ray absorptiometry (DXA) will be measured. In addition, The Six-Minute Walk Test (6MWT) and skeletal muscle function tests will be assessed at the end of each screening visit.
Each study visit will begin with vital signs. Before administration of the feeding or the tracer solution, baseline blood will be collected for measurement of the natural enrichment of metabolites. After the baseline sample is collected, feeding will begin and will be followed by tracers of several compounds that may be administered by IV pulse.
Next, the subjects will be fed one of six liquid nutritional supplement every 20 minutes for 6 hours. The liquid nutrition supplement will target the amino acid formulation in the following meals (1) total amino acid, (2) Essential Amino Acids (EAA), (3) EAA + -hydroxy -methylbutyric acid (HMB), (4) EAA + leucine (LEU), (5) EAA high, and (6) Placebo.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Healthy male older adults | Other | Dietary Supplement: Total Amino Acids, Dietary Supplement: Essential Amino Acids, Dietary Supplement: Essential Amino Acids + Hydroxy-methylbutyric acid (HMB), Dietary Supplement: Essential Amino Acids + Leucine, Dietary Supplement: Essential Amino Acids High, Dietary Supplement: Placebo WaterHealthy male older adults |
| Healthy female older adults | Other | Dietary Supplement: Total Amino Acids, Dietary Supplement: Essential Amino Acids, Dietary Supplement: Essential Amino Acids + Hydroxy-methylbutyric acid (HMB), Dietary Supplement: Essential Amino Acids + Leucine, Dietary Supplement: Essential Amino Acids High, Dietary Supplement: Placebo WaterHealthy female older adults |
Who may qualify
- Ages
- 60 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Age: 60-80, inclusive
- Stable body-weight (± 5%) for the past 3 months
- Subject is judged to be in satisfactory health based on medical history, physical examination, and laboratory screening evaluations.
- Ability to walk, sit down and stand up independently or with walking mobility aids
- Ability to lie in supine or elevated position for up to 7 hours
Key exclusion criteria (9 listed)
- Established diagnosis of current malignancy
- History of untreated metabolic diseases including hepatic or renal disorder
- Presence of acute illness or metabolically unstable chronic illness
- Presence of fever within the last 3 days
- Use of short course of oral corticosteroids within 4 weeks preceding study day
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 |
|---|---|---|
| Total Amino AcidsHistidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Alanine, Arginine, Aspartate, Cystine, Glutamine, Glutamate, Glycine, Proline, Serine, Tyrosine. All supplements are commercially available. | Dietary supplement | Healthy female older adults, Healthy male older adults |
| Essential Amino AcidsHistidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine. All supplements are commercially available. | Dietary supplement | Healthy female older adults, Healthy male older adults |
| Essential Amino Acids + Hydroxy-methylbutyric acid (HMB)Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, HMB. All supplements are commercially available. | Dietary supplement | Healthy female older adults, Healthy male older adults |
| Essential Amino Acids + LeucineHistidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Extra leucine. All supplements are commercially available. | Dietary supplement | Healthy female older adults, Healthy male older adults |
| Essential Amino Acids HighHistidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine. All supplements are commercially available. | Dietary supplement | Healthy female older adults, Healthy male older adults |
| Placebo WaterWater | Dietary supplement | Healthy female older adults, Healthy male older adults |
Primary outcome
Feeding related changes in whole-body protein and amino acid metabolism
Time frame: up to 6 hours
Whole-body production rate measured after stable tracer administration
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Oct 2026.
- Derived from this study: PubMed 42013668Knezek SB, Engelen MPKJ, Coyle KS, Perez CN, Deutz NEP. Adding free leucine to a balanced essential amino acid mixture suppresses intracellular transamination of isoleucine and valine in healthy older adults. Clin Nutr. 2026 Jun;61:106659. doi: 10.1016/j.clnu.2026.106659. Epub 2026 Apr 9.
- Derived from this study: PubMed 41260190Deutz NEP, Knezek SB, Engelen MPKJ. A novel pulse tracer method to estimate the relationship between amino acid meal composition and its intracellular disposal. Clin Nutr. 2025 Dec;55:196-207. doi: 10.1016/j.clnu.2025.10.002. Epub 2025 Oct 22.
- Individual participant dataSharing planned: Undecided. Data may be shared upon request for up to 6 years beyond completion of the trial based on methods/proposal approved by both parties' institutional review committees. Individual participant data that underlie the results of the trial may be shared after de-identification (text, tables, figures, and appendices). Additional documents available per request include: study protocol, statistical analysis plan, and informed consent. Requests should be directed to Dr. Marielle Engelen (mpkj.engelen@ctral.org).
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Total Amino Acids, Essential Amino Acids and Essential Amino Acids + Hydroxy-methylbutyric acid (HMB) in people with Protein Metabolism, run by Texas A&M University at 1 site in United States.
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 6 inclusion and 9 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: under way, not looking for participants, as of the sponsor's last update on 5 Oct 2026. 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 United States. 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?
This study is still under way. Results are not available in the source record yet.
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?
Feeding related changes in whole-body protein and amino acid metabolism (time frame: up to 6 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05400733, which also lists 2 linked publications.
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 5 Oct 2026.