Recruiting

IAAO Validation

Sponsor:

University of Toronto

Code:

NCT07317921

Conditions

Protein Metabolism

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Interventions

Protein + Stable Isotope Tracer Beverage

Study Details

Brief 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. 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

Study ID

NCT07317921

Start date

Dec 1, 2025

Status verified date

Dec, 2025

Completion date

May 20, 2026

Anticipated

Primary completion date

Mar 20, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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)

Study Design

Enrollment

8 participants

Anticipated

Intervention Model

Single group

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Protein + Stable Isotope Tracer Beverage

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.

Interventions

Protein + Stable Isotope Tracer Beverage

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

Primary outcome measure

  • Phenylalanine excretion (umol/kg/h) [ Time Frame: 6.5 hours ]
  • Phenylalanine oxidation (umol/kg/h) [ Time Frame: 6.5 hours ]
  • Myofibrillar protein synthesis (%/hr) [ Time Frame: 6.5 hours ]
  • Sarcoplasmic protein synthesis (%/hr) [ Time Frame: 6.5 hours ]

Central Contacts and Locations

Central contacts

Sabrina T Barsky, Ph.D.

16475400115sabrina.barsky@utoronto.ca

Locations

Kinesiology & Physical Education

Recruiting

Toronto, Ontario, Canada, M5S 2C9

Contacts

Sabrina T. Barsky, Ph.D.

16475400115sabrina.barsky@utoronto.ca

Principal Investigator:

Daniel Moore, Ph.D

More Information

Sponsor

University of Toronto

Last update posted

Jan 5, 2026

Last verified

Dec, 2025

Keywords

  • Muscle biopsy
  • Protein Metabolism
  • Stable isotopes
  • Protein oxidation
  • Indicator amino acid oxidation
  • Protein synthesis

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Toronto on 2026-01-05.