RecruitingOBSERVATIONAL

Impact Of A Phe-Restricted Diet On Gut Health In Children With PKU

This study investigates how different treatments for a condition called Phenylketonuria (PKU) affect the healthy bacteria in a child's gut. PKU is a lifelong condition where the body can't properly process a substance called phenylalanine found in food. The main treatment is a special diet. Some children also take medicine like sapropterin or sepiapterin, which can make the diet less strict. The researchers want to see if the gut bacteria are different in children on the diet compared to those also taking medication, and how they compare to healthy children living in the same home. Understanding these differences could help improve future nutritional advice for children with PKU.

At a glance

Status

Recruiting

Sponsor

Birmingham Women's and Children's NHS Foundation Trust

Enrolment target

148

Start

01 Oct 2025

Estimated completion

01 Dec 2026

Phenylketonuria

What is this study about?

This study is about understanding how managing Phenylketonuria (PKU) affects the helpful bacteria that live in a child's gut, often called the ‘gut microbiome’. PKU is a condition children are born with where their bodies can't break down a certain part of protein called phenylalanine. To stay healthy and prevent problems with brain development, children with PKU follow a very special, strict diet with low amounts of phenylalanine. Some children also take medicines, like sapropterin or sepiapterin, which can help their bodies handle more phenylalanine, potentially making their diet a bit easier to manage.

Doctors already know that what we eat has a big impact on the bacteria in our gut. However, we don't fully understand how the special diet for PKU, or the medicines taken alongside it, change these important gut bacteria. This study aims to find out if there are differences in the types and functions of gut bacteria between children with PKU who are on the diet alone, those who are also taking medicines, and healthy children who live in the same house.

By comparing these groups, the researchers hope to learn more about how PKU treatment, the strictness of the diet, and these gut bacteria are all connected to a child's overall gut health. The findings could be very important as they might help doctors and dietitians give better advice on diet and nutrition for children and young people with PKU in the future.

Key takeaways

This study explores how PKU treatments affect gut bacteria.
It involves children with PKU on diet alone, or diet plus medication, and healthy siblings.
Participation requires a single stool sample and sharing health information.
No changes to your child's PKU treatment are made by the study.
The findings could help improve future dietary advice for children with PKU.

Who may be eligible?

This study is looking for children and teenagers with PKU, aged between 3 and 17 years old. They need to have been diagnosed with PKU through the newborn screening tests and currently be receiving ongoing care for their condition.

There are three main groups of children with PKU the study wants to include: those who are only managing their PKU with the special low-phenylalanine diet; those who are taking sapropterin medication alongside their diet; and those who are taking sepiapterin medication with their diet. For children taking medication, they need to have been on it for at least three months and seen a good improvement in their ability to eat more natural protein.

The study also needs healthy children or teenagers who live in the same house as a child with PKU taking part. These household members must be aged 3 years or older and not have PKU or any other inherited metabolic condition. Importantly, children cannot take part if they have certain other health problems like long-term stomach or bowel issues, other ongoing serious illnesses, or if they've been on a special diet for another medical condition (other than PKU) in the last six months.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Is your child aged between 3 and 17 years old?
Does your child have a confirmed diagnosis of PKU?
Is your child currently receiving ongoing treatment for PKU (diet alone or diet plus sapropterin/sepiapterin)?
If your child is taking sapropterin or sepiapterin, have they been on it for at least 3 months and seen a good improvement in their diet?
Does your child NOT have other serious long-term tummy problems or other major health conditions?

Answer every question to see your result.

What does participation involve?

If you or your child decides to take part, it's a relatively simple process. This is an 'observational study', which means researchers will collect information and samples without changing your child's usual PKU treatment or diet. Your child will not be given any new medicines or treatments as part of the study; everything related to their PKU care, including their diet and any medication, will continue as normal under their own doctors.

The main thing involved is providing a single stool (poo) sample. Your child will also be asked about what they eat, any tummy problems they might have, and details about their stool. The study team will also collect some general health information. You only need to provide one sample and answer these questions once. There are no follow-up visits or long-term commitments for the study itself; the entire participation is a single event.

Potential risks and benefits

The benefits of taking part are not directly for your child’s health, as this study doesn't offer a new treatment. However, the information gained from children taking part could help improve future care and dietary advice for all children with PKU. The risks are very low; providing a stool sample is generally safe and causes no discomfort. Discussing dietary and health information is also very safe. You are free to withdraw your child from the study at any time without giving a reason, and this decision will not affect your child's medical care in any way.

Locations (1)

Birmingham Children's Hospital
Verified postcode
Birmingham, United Kingdom· Recruiting

Common questions

What is PKU?

PKU, or Phenylketonuria, is a condition where the body can't process a part of protein called phenylalanine, which can cause health problems if not managed with a special diet.

What will my child have to do if they join?

Your child will provide one stool (poo) sample and answer some questions about their diet and tummy health. Their PKU treatment will stay exactly the same.

Will my child get any new medicine in this study?

No, this study is about observing current treatments. Your child will not be given any new medicine or change their existing PKU treatment because of the study.

How long will my child be involved?

Participation is a one-off event, involving providing a sample and answering questions. There are no ongoing visits or treatments for the study itself.

Why is a healthy family member also included?

Including a healthy family member helps researchers compare gut bacteria in similar environments to better understand differences linked to PKU treatment.

How to find out more

Anita MacDonald, PhD

anita.macdonald@nhs.net +44 121 333 9999 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.