Protein MetabolismVIMNCT07317921
Validating IAAO for Muscle Outcomes
A study testing Protein + Stable Isotope Tracer Beverage in people with Protein Metabolism, run by University of Toronto at 1 site in Canada.
Trial summary
Consuming dietary protein stimulates whole-body and muscle protein synthesis, the latter of which is typically measured using invasive primed constant infusions of stable isotopes with concurrent muscle biopsies. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Protein Metabolism
- What is being tested?
- Protein + Stable Isotope Tracer Beverage
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 8 participants
- Where
- 1 siteCanada
- Study dates
- 1 Dec 2025to 20 May 2026
- 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 18 to 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Participants will be aged 18-35 years old
- Participants will have a BMI within the normal range (i.e., 18.5-24.9) and waist-to-hip circumference ratio of <0.95 for males and <0.8 for circumference for females to ensure homogeneity of the sample population
- Participants are willing to abide by the compliance rules of this study (e.g., abstain from extraneous physical activity 48h prior to session 4
- Self-reported regular menstrual cycle (25-35d) within the last 3 months (female participants)
- Physical activity score of ≥24 units as measured by the Godin leisure time exercise questionnaire
Who cannot join
- Inability to adhere to any of the compliance rules judged by principal investigator
- Self-reported regular tobacco or illicit drug use (e.g., growth hormone or testosterone)
- Current use of hormonal contraceptives
- Individuals with a history of allergy to local anesthetics (e.g., lidocaine)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
Kinesiology & Physical Education
Toronto, Ontario, M5S 2C9
Sabrina T. Barsky, Ph.D., 16475400115, sabrina.barsky@utoronto.ca
Daniel Moore, Ph.D
About this study
Official title: Validating the Indicator Amino Acid Oxidation Technique for Muscle Outcomes
Consuming dietary protein stimulates whole-body and muscle protein synthesis, the latter of which is typically measured using invasive primed constant infusions of stable isotopes with concurrent muscle biopsies. Alternative non-invasive methodologies have been developed (namely the indicator amino acid oxidation (IAAO) technique) to estimate the impact of protein ingestion on whole-body protein synthesis as a proxy for determining dietary protein requirements. Given that the IAAO technique is based on principles of protein metabolism which occur in the liver, it is unclear how representative the IAAO outcomes of whole-body protein synthesis is to skeletal muscle protein synthesis. Validation of the IAAO technique against gold-standard, biopsy-derived measures of muscle metabolism (i.e., muscle protein synthesis) would assist in mitigating the invasiveness of muscle physiology and nutrition research.
- Conditions
- Protein Metabolism
- Being tested
- Protein + Stable Isotope Tracer Beverage
- Keywords
- Muscle biopsy, Protein Metabolism, Stable isotopes, Protein oxidation, Indicator amino acid oxidation, Protein synthesis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Protein + Stable Isotope Tracer BeverageDietary supplement
Participants will consume 12 half-hourly (6 hours) isoenergetic, isonitrogenous beverages containing 0.9g/kg fat-free mass/day protein. Drinks will be enriched with stable isotopes [2H5]Phenylalanine and [1-13C]Phenylalanine, which will respectively allow for determination of muscle protein synthesis and whole-body protein synthesis over the subsequent 6 hours of feeding
| Study group | Role | What they receive |
|---|---|---|
| Protein + Stable Isotope Tracer Beverage | Experimental | Participants will consume 12 half-hourly (6 hours) isoenergetic, isonitrogenous beverages containing 0.9g/kg fat-free mass/day protein. Drinks will be enriched with stable isotopes [2H5]Phenylalanine and [1-13C]Phenylalanine, which will respectively allow for determination of muscle protein synthesis and whole-body protein synthesis over the subsequent 6 hours of feeding. Receives: Dietary Supplement: Protein + Stable Isotope Tracer Beverage |
What is being measured
The primary outcome is the main question the study is designed to answer.
Phenylalanine excretion (umol/kg/h)
Rate of whole-body phenylalanine excretion following orally ingested amino acid tracer [1-13C]Phenylalanine determined from the product of breath 13CO2 enrichment and carbon dioxide production rate (VCO2).
Measured: 6.5 hours
Phenylalanine oxidation (umol/kg/h)
Rate of whole-body phenylalanine oxidation following orally ingested amino acid tracer [1-13C]Phenylalanine determined from the correction of phenylalanine excretion by the phenylalanine precursor enrichment via urine enrichment.
Measured: 6.5 hours
Myofibrillar protein synthesis (%/hr)
Rate of myofibrillar fractional synthesis is determined by rate of incorporation of orally ingested tracer [2H5]Phenylalanine into myofibrillar proteins (isolated from skeletal muscle biopsies) and the enrichment of [2H5]Phenylalanine in plasma collected over the 6 hours protein consumption period. Enrichment will be quantified via tandem LC-MS/MS to derive a rate of incorporation over the 6-hour period.
Measured: 6.5 hours
Sarcoplasmic protein synthesis (%/hr)
Rate of sarcoplasmic fractional synthesis is determined by rate incorporation of orally ingested tracer [2H5]Phenylalanine into sarcoplasmic (ie., soluble) proteins (isolated from skeletal muscle biopsies) and the enrichment of [2H5]Phenylalanine in plasma collected over the 6 hours protein consumption period. Enrichment will be quantified via tandem LC-MS/MS to derive a rate of incorporation over the 6-hour period.
Measured: 6.5 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Jan 2026
- Study start1 Dec 2025
- Primary completion20 Mar 2026 (estimated)
- Study completion20 May 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- 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
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Single group: Eight healthy young (18-35 years, 4 females and 4 males) will be subjected to 2 skeletal muscle biopsies, collection of blood and urine samples, and a non-invasive 13CO2 breath-test over a 6.5-hour period while ingesting half-hourly protein beverages with stable isotope tracers. The breath-test is based on the indicator amino acid oxidation (IAAO) method.
- Masking
- None (open label)
- Enrolment
- 8 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Toronto
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Daniel Moore, University of Toronto
- Investigators
- Daniel Moore, Ph.D, Principal investigator, University of Toronto, Faculty of KPE
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07317921
- Sponsor's protocol ID
- VIM
- Acronym
- VIM
- Status last verified
- Dec 2025
- First submitted
- 18 Dec 2025
- Last updated
- 5 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 5 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Validating the Indicator Amino Acid Oxidation Technique for Muscle Outcomes
- ClinicalTrials.gov ID
- NCT07317921
- Acronym / sponsor ID
- VIM / VIM
- Conditions
- Protein Metabolism
- Keywords
- Muscle biopsy, Protein Metabolism, Stable isotopes, Protein oxidation, Indicator amino acid oxidation, Protein synthesis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 8 participants (estimated)
- Lead sponsor
- University of TorontoUniversity, hospital or other
- Study start
- 1 Dec 2025 (actual)
- Primary completion
- 20 Mar 2026 (estimated)
- Study completion
- 20 May 2026 (estimated)
- First posted
- 5 Jan 2026 (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.
Consuming dietary protein stimulates whole-body and muscle protein synthesis, the latter of which is typically measured using invasive primed constant infusions of stable isotopes with concurrent muscle biopsies. Alternative non-invasive methodologies have been developed (namely the indicator amino acid oxidation (IAAO) technique) to estimate the impact of protein ingestion on whole-body protein synthesis as a proxy for determining dietary protein requirements. Given that the IAAO technique is based on principles of protein metabolism which occur in the liver, it is unclear how representative the IAAO outcomes of whole-body protein synthesis is to skeletal muscle protein synthesis. Validation of the IAAO technique against gold-standard, biopsy-derived measures of muscle metabolism (i.e., muscle protein synthesis) would assist in mitigating the invasiveness of muscle physiology and nutrition research.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Single group: Eight healthy young (18-35 years, 4 females and 4 males) will be subjected to 2 skeletal muscle biopsies, collection of blood and urine samples, and a non-invasive 13CO2 breath-test over a 6.5-hour period while ingesting half-hourly protein beverages with stable isotope tracers. The breath-test is based on the indicator amino acid oxidation (IAAO) method.
| Arm | Type | Receives |
|---|---|---|
| Protein + Stable Isotope Tracer Beverage | Experimental | Dietary Supplement: Protein + Stable Isotope Tracer BeverageParticipants will consume 12 half-hourly (6 hours) isoenergetic, isonitrogenous beverages containing 0.9g/kg fat-free mass/day protein. Drinks will be enriched with stable isotopes [2H5]Phenylalanine and [1-13C]Phenylalanine, which will respectively allow for determination of muscle protein synthesis and whole-body protein synthesis over the subsequent 6 hours of feeding. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Participants will be aged 18-35 years old
- Participants will have a BMI within the normal range (i.e., 18.5-24.9) and waist-to-hip circumference ratio of <0.95 for males and <0.8 for circumference for females to ensure homogeneity of the sample population
- Participants are willing to abide by the compliance rules of this study (e.g., abstain from extraneous physical activity 48h prior to session 4
- Self-reported regular menstrual cycle (25-35d) within the last 3 months (female participants)
- Physical activity score of ≥24 units as measured by the Godin leisure time exercise questionnaire
Key exclusion criteria (4 listed)
- Inability to adhere to any of the compliance rules judged by principal investigator
- Self-reported regular tobacco or illicit drug use (e.g., growth hormone or testosterone)
- Current use of hormonal contraceptives
- Individuals with a history of allergy to local anesthetics (e.g., lidocaine)
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 |
|---|---|---|
| Protein + Stable Isotope Tracer BeverageParticipants will consume 12 half-hourly (6 hours) isoenergetic, isonitrogenous beverages containing 0.9g/kg fat-free mass/day protein. Drinks will be enriched with stable isotopes [2H5]Phenylalanine and [1-13C]Phenylalanine, which will respectively allow for determination of muscle protein synthesis and whole-body protein synthesis over the subsequent 6 hours of feeding | Dietary supplement | Protein + Stable Isotope Tracer Beverage |
Primary outcome
Phenylalanine excretion (umol/kg/h)
Time frame: 6.5 hours
Rate of whole-body phenylalanine excretion following orally ingested amino acid tracer [1-13C]Phenylalanine determined from the product of breath 13CO2 enrichment and carbon dioxide production rate (VCO2).
Phenylalanine oxidation (umol/kg/h)
Time frame: 6.5 hours
Rate of whole-body phenylalanine oxidation following orally ingested amino acid tracer [1-13C]Phenylalanine determined from the correction of phenylalanine excretion by the phenylalanine precursor enrichment via urine enrichment.
Myofibrillar protein synthesis (%/hr)
Time frame: 6.5 hours
Rate of myofibrillar fractional synthesis is determined by rate of incorporation of orally ingested tracer [2H5]Phenylalanine into myofibrillar proteins (isolated from skeletal muscle biopsies) and the enrichment of [2H5]Phenylalanine in plasma collected over the 6 hours protein consumption period. Enrichment will be quantified via tandem LC-MS/MS to derive a rate of incorporation over the 6-hour period.
Sarcoplasmic protein synthesis (%/hr)
Time frame: 6.5 hours
Rate of sarcoplasmic fractional synthesis is determined by rate incorporation of orally ingested tracer [2H5]Phenylalanine into sarcoplasmic (ie., soluble) proteins (isolated from skeletal muscle biopsies) and the enrichment of [2H5]Phenylalanine in plasma collected over the 6 hours protein consumption period. Enrichment will be quantified via tandem LC-MS/MS to derive a rate of incorporation over the 6-hour period.
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 Jan 2026.
- Individual participant dataSharing planned: Undecided
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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.
Daniel Moore, Ph.D principal investigator
University of Toronto, Faculty of KPE
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Protein + Stable Isotope Tracer Beverage in people with Protein Metabolism, run by University of Toronto at 1 site in Canada.
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 5 inclusion and 4 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: looking for participants now, as of the sponsor's last update on 5 Jan 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 Canada. 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?
Contact Sabrina T Barsky, Ph.D. (16475400115, sabrina.barsky@utoronto.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Phenylalanine excretion (umol/kg/h) (time frame: 6.5 hours). The study lists 4 primary outcomes in all. 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 5 Jan 2026.