An interventional study of GMP Intervention Product in Phenylketonuria and Tyrosinemia, sponsored by Nutricia UK Ltd. Recruiting at 1 site in United Kingdom. Open to participants aged 3 Years and older. Per ClinicalTrials.gov, last updated 2025-12-19.
Sponsored by Nutricia UK Ltd (part of Danone) · Not applicable, Interventional, and Basic science
Four new GMP-based protein substitutes have been developed to support the dietary management of PKU and TYR. These products are powdered protein substitutes, low in phenylalanine and low in phenylalanine and tyrosine respectively, with a mix of glycomacropeptide (GMP), essential and non-essential amino acids, carbohydrates, fibres, fats (including DHA) and micronutrients. The proteins in these new protein substitutes are based on GMP, a peptide isolated from milk during cheese manufacturing and the only known naturally derived protein source low in phenylalanine and tyrosine. The GMP is supplemented with other amino acids which are naturally low or not present in GMP, as well as carbohydrates, fats, fibre and micronutrients. Studies to date have illustrated that PKU patients who replace their regular phenylalanine-free amino acid-based formula with GMP-based foods may have better diet compliance and prefer the taste whilst maintaining metabolic control.
This series of case-studies aims to evaluate the gastrointestinal tolerance, acceptability, compliance, and safety of these four GMP based protein substitutes in both adults and children over 3 years. These case studies will last 29 days in total, including a 1-day baseline period followed by a 28-day intervention period. The case studies will be conducted across multiple specialist metabolic centres in the UK. A series of case studies is undertaken due to the rarity of these conditions, the diversity of patient types and the difficulty in recruiting these patients to trials.
191 studies on the registry are indexed under Phenylketonurias; 40 are open to participants now.
This study's planned enrollment of 40 is above the median of 27 across 122 interventional studies indexed under Phenylketonurias.
Browse Phenylketonurias studies →Nutricia UK Ltd is the lead sponsor of 28 studies on the registry; 5 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Dietary Supplement: GMP Intervention Product
Condition specific GMP based intervention product
Gastro-intetsinal tolerance
GI tolerance will be recorded by the Dietitian at baseline on Day 1 and at the end of the case study period (Day 29). GI tolerance will be recorded using a standardised questionnaire to capture perceived severity (none, mild, moderate or severe) of common gastrointestinal symptoms (diarrhoea, constipation, bloating, abdominal discomfort, vomiting and nausea). Information about appearance of stools will also be collected using the Bristol Stool Chart© at the same time points.
Time frame: Measured at baseline (day 1) and end of intervention (day 29)
Acceptability
Acceptability (ease of use and liking) of the patients' usual protein substitute and the study product will be assessed by the Dietitian at baseline (Day 1) and the end of the case study period (Day 29) by a series of questions posed to the patient and/or parent/caregiver. Acceptability questions will assess the patient's sensory experience, ease of use, tolerance, and overall self-rated acceptability on a 5-point Likert scale.
Time frame: Measured at baseline (day 1) and end of intervention (day 29)
Compliance
Compliance with the recommended intake of the patients' usual protein substitute (during baseline) and with the study product (during the case study period) will be assessed by the Dietitian at baseline (Day 1) and at the end of the case study (Day 29). Patients and/or parents/caregivers will be asked to recall the amount of their protein substitute taken in the past 24 hours and on average. This will be compared to the amount recommended to be consumed by their Dietitian. The daily amount prescribed by the Dietitian managing the patient's care will be recorded at the start of the case study and any changes to this prescription during the case study will also be noted.
Time frame: Measured at baseline (day 1) and end of intervention (day 29)
Blood phenylalanine, blood tyrosine and other amino acid levels
Dietitians will be asked to record recent phenylalanine, tyrosine and other amino acid levels (and subsequent reference ranges) that are taken as part of normal clinical practice on Day 1 and at the end of the case study (Day 29), performed as a part of their routine care. Dietitians will also be asked to describe the patient's metabolic control during the case study period.
Time frame: Day 1 (baseline) and day 29 (end of intervention)
Anthropometry
For safety purposes, at baseline (Day 1) and at the end of the case study (Day 29), body weight (kg) will be measured where possible using standard methods, recorded to the nearest 0.1kg using a weighing scale without heavy clothing. Height will also be measured, using standard methods, recorded to the nearest 0.1cm (at baseline only) and used to calculate body mass index (BMI, kg/m2).
Time frame: Day 1 (baseline) and day 29 (end of intervention)
Patient history
A detailed patient history will be recorded at baseline to assess previous compliance to protein substitutes, relevant medical and clinical issues, medication(s) prescribed, and any other relevant information related to the patient's condition or dietary management.
Time frame: Day 1 (baseline) and day 29 (end of intervention)
Safety/ Adverse Events
All adverse events will be recorded, throughout the case study.
Time frame: Throughout the case study series (day 1 to day 29).
Plan to share: No
No publications or documents are linked to this record.
Started May 2025 (actual). Primary completion is estimated for Dec 2026, 19 months after the start.
Of 33 interventional studies with no phase under Phenylketonurias, half reached primary completion within 22 months of starting (the median), counting those still running; a quarter within 9 and three quarters within 28. This study's planned 19 months is below that.
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