Phe for Me? The Effects of L-Phe on PKU Carriers and Non-carriers

NCT06119048 | Completed

• 1 other identifier: 23-03-017
• Study Type: interventional
• Target: 56
• Locations: 1 country
• Sites: 1

Brief Summary

This is a clinical intervention study of PKU carriers (cases) and non-carriers (controls). Upon completing the informed consent process, participants will complete baseline measures of chronic mental health prior to the intervention (PHQ-9, GAD-7, BIS-11). Participants will attend the Human Nutraceutical Research Unit (HNRU) at the University of Guelph, fasted, and first undergo baseline measures of cognition and acute mental health (mood) and provide samples or saliva, urine and dried blood spots to evaluate phenylalanine (Phe), tyrosine (Tyr) and their metabolites (PAH pathway functioning) as well as for genetic testing of the PAH gene. Participants will also complete a brief questionnaire which will include age, sex, ethnicity, income, weight and height (measured using a stadiometer and calibrated weigh scale), and confirmation that participants arrived to the lab fasted (i.e. have only had water to drink and no other foods/ beverages prior to analyses). Blood pressure and heart rate will also be measured at baseline. Following baseline tests, participants will consume a pure L-Phe supplement dosed at 100 mg/kg mixed with 125 mL of water and 125mL of orange juice. Blood pressure and heart rate will be repeated at 1-hour post-L-Phe consumption. Two-hours postprandial, participants will repeat the cognitive tests and acute mental health (mood) assessment, blood pressure and heart rate measurement and provide follow-up saliva, urine and dried blood spot samples. Participants will also be asked to report any side effects they experienced with the L-Phe consumption.

Conditions

Autosomal Recessive Disorder (Genetic Carriers of PKU)

Outcome Measures

Primary Outcomes (1)

• Stop Signal Reaction Time

  Response Inhibition

  Change from baseline to 2-hours post L-Phe supplementation

Secondary Outcomes (10)

• Working Memory

  Change from baseline to 2-hours post L-Phe supplementation

• Individual Coefficient of Variance (Variability in Reaction Time)

  Change from baseline to 2-hours post L-Phe supplementation

• Phenylalanine Levels

  Change from baseline to 2-hours post L-Phe supplementation

• Tyrosine Levels

  Change from baseline to 2-hours post L-Phe supplementation

• Phenylalanine Metabolites

  Change from baseline to 2-hours post L-Phe supplementation

Other Outcomes (4)

• Chronic Anxiety

  Baseline

• Chronic Depression

  Baseline

• Impulsivity

  Baseline

Study Arms (1)

Genetic Carriers and Non-Carriers of PKU

EXPERIMENTAL

Dietary Supplement: L-Phenylalanine

Interventions

L-Phenylalanine DIETARY_SUPPLEMENT

100 mg/kg

Genetic Carriers and Non-Carriers of PKU

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Carrier or non-carrier of PKU
• At least 18 Years of age
• Comfortable fasting the morning of the study (no food or drink other than water)

You may not qualify if:

• Diagnosed with: PKU, severe neurodegenerative conditions affecting cognition (e.g. Alzheimer's, Parkinson's, dementia), melanoma, hypertension, liver disease and/or kidney disease
• Diagnosed with hypertension or hypotension
• Taking a monoamine oxidase inhibitor anti-depressant
• Pregnant or breastfeeding
• Orange/citrus allergy or intolerance
• Body weight 150 kg or greater
• History of fainting during blood sampling

Sponsors & Collaborators

• University of Guelph: lead
• McMaster University: collaborator
• Laval University: collaborator

Study Sites (1)

University of Guelph

Guelph, Ontario, N1G 2W1, Canada

Location

MeSH Terms

Interventions

Phenylalanine

Intervention Hierarchy (Ancestors)

Amino Acids, Aromatic; Amino Acids, Cyclic; Amino Acids; Amino Acids, Peptides, and Proteins; Amino Acids, Essential

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: OTHER
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: October 31, 2023
• First Posted: November 7, 2023
• Study Start: June 18, 2024
• Primary Completion: October 3, 2025
• Study Completion: October 3, 2025
• Last Updated: May 4, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

CA (1)