Impact of Phenylketonuria-type Diet on Appetite, Appetite Hormones and Diet Induced Thermogenesis

Study Overview
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Brief Summary
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Low-phenylalanine diets are commonly prescribed to people with phenylketonuria (PKU), an inborn disease which causes accumulation of amino acid phenylalanine (Phe) in the blood. High blood Phe levels can cause mental, behavioural, neurological, and physical problems. Thus, low-phenylalanine diets help patients to manage their condition but it is not clear whether they have an impact on appetite, energy intake and changes in body weight. This is important to explore as prevalence of obesity in this population is rising high. This study aims to find out the effect of PKU-type meals on appetite, appetite biomarkers, and post-meal energy expenditure. The investigators will recruit 26 healthy adults and ask them to participate in two experimental trials. On one occasion the participants will be asked to consume a PKU-supplemented drink followed by a PKU type-lunch and on another occasion the supplement and lunch will be based on normally consumed foods. Series of blood samples will be taken and appetite will be assessed during both experiments. Both experimental trials will finish with consuming an all-you-can-eat buffet.

Official Title
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Impact of Phenylketonuria-type Diet on Appetite, Appetite Hormones and Diet Induced Thermogenesis

Conditions
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Phenylketonuria (PKU)

Intervention / Treatment
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* Dietary Supplement: Phenylketonuria-type diet
* Other: Normal (control) diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy adult Body weight stable for previous 4 months Regular menstrual cycle (females) Exclusion Criteria: Pregnancy or lactation (females) History of eating disorder History of gastrointestinal problems or surgery History of allergy History of chronic illness On any medication Smoking On nutritional supplements Following specific diet Currently taking part in other research

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Phenylketonuria-type diet<br>Breakfast: one pouch of amino acid supplement (174 mls supplemented drink PKU cooler 20, Vitaflo®; 20 g protein, 9.4 g carbohydrates, 0.7 g Fat) Lunch: cheese sandwich [low protein bread (Juvela, UK), no protein vegan cheese (Viotros, UK)], low protein crackers (Vitaflo, UK), and low protein cookies (Juvela, UK). Dinner: ad libitum buffet meal | Dietary Supplement: Phenylketonuria-type diet<br>* Breakfast, lunch and open buffet dinner<br>Other: Normal (control) diet<br>* Breakfast, lunch and open buffet dinner<br>|
| Other: Normal diet<br>Breakfast: 174 ml of milk (20 g protein, 9.4 g carbohydrates, 0.7 g Fat) Lunch: cheese sandwich, crackers, and cookies (regular foods) Dinner: ad libitum buffet meal | Dietary Supplement: Phenylketonuria-type diet<br>* Breakfast, lunch and open buffet dinner<br>Other: Normal (control) diet<br>* Breakfast, lunch and open buffet dinner<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Appetite hormone: peptide YY (PYY) | Plasma concentration at baseline (0 minute) and after ingestion of supplement (at 30, 60 and 90 minutes) and lunch (at 120, 150,180, 210, 240, 270 and 300 minutes) | 300 minutes | 
| Appetite hormone: glucagon-like peptide-1 (GLP-1) | Plasma concentration at baseline (0 minute) and after ingestion of supplement (at 30, 60 and 90 minutes) and lunch (at 120, 150,180, 210, 240, 270 and 300 minutes) | 300 minutes | 
| Appetite hormone: cholecystokinin (CCK) | Plasma concentration at baseline (0 minute) and after ingestion of supplement (at 30, 60 and 90 minutes) and lunch (at 120, 150,180, 210, 240, 270 and 300 minutes) | 300 minutes | 
| Appetite hormone: insulin | Plasma concentration at baseline (0 minute) and after ingestion of supplement (at 30, 60 and 90 minutes) and lunch (at 120, 150,180, 210, 240, 270 and 300 minutes) | 300 minutes | 
| Appetite hormone: ghrelin | Plasma concentration at baseline (0 minute) and after ingestion of supplement (at 30, 60 and 90 minutes) and lunch (at 120, 150,180, 210, 240, 270 and 300 minutes) | 300 minutes | 
| Subjective appetite score | Visual analogue scale (VAS) collected at baseline and after each blood sample collection | 300 minutes | 
| Diet induced thermogenesis | Metabolic rate by means of computerised open-circuit ventilated hood system collected at baseline and after each blood sample collection for the duration of 20 minutes | 300 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Taste perception of PKU supplements/foods | Immediately after supplement ingestion and lunch consumption | 10 minutes | 
| Consumption time for PKU supplements/foods | Maximum 5 minutes for supplement ingestion and maximum 20 minutes for lunch consumption | 20 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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low Phenylalanine diet, PKU supplements, diet induced thermogenesis, appetite, body weight