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NCT Number: NCT06794515

cGMP: Metabolism and Appetite Modulation

Phenylketonuria is an inborn error of phenylalanine metabolism. Although the phenylalanine-restricted diet is recognized as the mainstay of therapy, little is known about the impact of protein substitutes on the metabolism of patients with phenylketonuria.

Therefore, the aim of this project is to study the impact of acute ingestion of casein glycomacropeptide supplemented with amino acids (cCGMP-AAs) alone or in combination with two different meals on amino acid absorption kinetics, glycaemic and insulinemic response, and on acute markers of appetite control.

The main findings of this project will bring new insights into the dietary management of these patients, which may lead to improvements in protein substitutes formulations.

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Key information

Conditions

Healthy

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

NOVA Medical School|Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisboa,

Lisbon, 1169-056, Portugal

Location contact

Ana Faria, PhD

CONTACT

[email protected]

00351218803033

Ana Faria, PhD

PRINCIPAL_INVESTIGATOR

Anita MacDonald, PhD

PRINCIPAL_INVESTIGATOR

Catarina Rodrigues, MSc

CONTACT

[email protected]

00351218803033

Catarina Rodrigues, MSc

SUB_INVESTIGATOR

Conceição Calhau, PhD

SUB_INVESTIGATOR

Júlio César Rocha, PhD

PRINCIPAL_INVESTIGATOR

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Men or women
  • Adults (age ≥ 18 years)
  • Body Mass Index (BMI) between 18.5-25.0 kg/m2
  • Filling informed consent

Exclusion criteria

  • Clinically significant illness
  • Have changed frequency, duration, or intensity of physical activity in the last month
  • Taking protein supplements
  • Pregnant or breastfeeding
  • Smoking and drug use

Treatment and study plan

cGMP-AAs alone (20 g of protein equivalent)

Dietary Supplement

cGMP-AAs alone (20 g of protein equivalent)

cGMP-AAs (20 g of protein equivalent) + 50 g of low-protein bread + 160 g of unpeeled apple

Dietary Supplement

cGMP-AAs (20 g of protein equivalent) + 50 g of low-protein bread + 160 g of unpeeled apple

cGMP-AAs (20 g of protein equivalent) + 50 g of low-protein bread + 10 g of olive oil

Dietary Supplement

cGMP-AAs (20 g of protein equivalent) + 50 g of low-protein bread + 10 g of olive oil

Primary outcomes

  1. Changes in the iAUC (mmol/L*min) for total amino acids

    Time frame: 180 minutes

    Total amino acids will be measured in fasting and every 30 minutes up to 180 minutes. The iAUC (mmol/L*min) for amino acids will be calculated based on the concentration curve following consumption of the test meal.

  2. Changes in the iAUC (pmol/L*min) for glucagon-like peptide-1 (GLP-1)

    Time frame: 180 minutes

    GLP-1 will be measured in fasting and every 30 minutes up to 180 minutes. The iAUC (pmol/L*min) for GLP-1 will be calculated based on the concentration curve following consumption of the test meal.

  3. Changes in the iAUC (pmol/L*min) for Cholecystokinin (CCK)

    Time frame: 180 minutes

    CCK will be measured in fasting and every 30 minutes up to 180 minutes. The iAUC (pmol/L*min) for CCK will be calculated based on the concentration curve following consumption of the test meal.

  4. Changes in the iAUC (pmol/L*min) for peptide YY (PYY)

    Time frame: 180 minutes

    PYY will be measured in fasting and every 30 minutes up to 180 minutes. The iAUC (pmol/L*min) for PYY will be calculated based on the concentration curve following consumption of the test meal.

  5. Changes in the iAUC (pmol/L*min) for Gastric inhibitory polypeptide (GIP)

    Time frame: 180 minutes

    GIP will be measured in fasting and every 30 minutes up to 180 minutes. The iAUC (pmol/L*min) for GIP will be calculated based on the concentration curve following consumption of the test meal.

Secondary outcomes

  1. Changes in glucose

    Time frame: 180 minutes

    Glucose will be measured in fasting and every 30 minutes up to 3 hours. The iAUC (mmol/L*min) for glucose will be calculated based on the concentration curve following consumption of the test meal.

  2. Changes in insulin

    Time frame: 180 minutes

    Insulin will be measured in fasting and every 30 minutes up to 3 hours. The iAUC (mmol/L*min) for insulin will be calculated based on the concentration curve following consumption of the test meal.

  3. Changes in C-peptide

    Time frame: 180 minutes

    C-peptide will be measured in fasting and every 30 minutes up to 3 hours. The iAUC (mmol/L*min) for C-peptide will be calculated based on the concentration curve following consumption of the test meal.

Sponsors and collaborators

Lead sponsor

Universidade Nova de Lisboa

Other

Registry information

Official study title

Metabolic Effects of cGMP: From Amino Acid Absorption Kinetics to Appetite Modulation

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jan 27, 2025
Registry last updated
Jan 27, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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