What should a PKU diet be

Don't leave people with phenylketonuria alone

09/05/2020 - Around 1 in 8,000 children in Europe are born with phenylketonuria (PKU) - a rare disease that affects protein metabolism. It can "lead to severe mental developmental disorders," explains Dr. Anja Reichert, Medical Director at the biotechnology company BioMarin in Germany. Patients need lifelong treatment. According to studies, however, only twelve percent of those affected in Europe receive adequate medical care.

No meat, no fish, and no cheese; Legumes, commercial bread, pasta or rice are also out of the question for people with PKU. The reason: These foods contain too much protein.

Due to their illness, PKU sufferers have to adhere to a strictly low-protein diet. Because your body cannot break down the amino acid phenylalanine (Phe) contained in protein well. The reason is mutations in a certain gene, which means that the enzyme with the complicated name phenylalanine hydroxylase (PAH) cannot work or can only work to a limited extent. The result: excessive Phe levels in the blood and brain. In addition to severe mental developmental disorders, epilepsy, spasticity or overexcitability, among other things, can occur without treatment, says Dr. Anja Reichert, BioMarin.

Strict diet for PKU: "very stressful"

"PKU is a rare disease, but it is one of the most common hereditary metabolic disorders," explains the doctor. The diagnosis is usually made immediately after the birth using the newborn screening, which has been in place in Germany since 1969. "The default is that you start the treatment in the first ten days". The focus is on the strict, low-protein diet: It is "very stressful", says Reichert.

“Only natural foods that contain almost exclusively carbohydrates or fats come into question.” There is not much left: selected fruit and vegetables. For things like pasta or bread, those affected have to fall back on low-protein special preparations that can be bought online. “The patients' bodies still need a lot of protein. This is replaced by completely synthetic mixtures in the form of shakes: They contain all amino acids except Phe. "

As part of the “Live Unlimited PKU” campaign, which is financially supported by BioMarin, PKU patient Eva looks back on her childhood: “I felt uncomfortable while eating. Everyone ate something ‘normal’, only my food looked strange. Sometimes there were comments from the other children like 'What's that?' Or '' That looks like poop shit. '"

In addition, eating is a central part of our social life: “But spontaneous dining out with family, friends or colleagues is simply not possible. That is really restrictive, ”Reichert regrets. Would you like to go to the restaurant? An almost hopeless endeavor.

PKU patients in a vicious circle

"Children still adhere to the diet quite well because their parents are very strict about it," she explains. “But after puberty there are fewer and fewer young people who go through the diet completely. And only very few of the adults make it. "

An improper diet causes Phe levels in the blood to rise. "Various neurological and psychological problems arise - for example, concentration disorders, headaches, waning attention or even paralysis". It is a creeping process that drags on for years - those affected often go unnoticed by how much their performance is declining. But the worse they are, the more they lack the drive to follow a strict diet - a vicious circle.

Available PKU therapy options

In addition to a selection of dietary foods for PKU patients, there are two drug options - both from BioMarin. The oral drug is used in PKU patients of all ages, provided that they respond to this therapy in a previous test. The second option - injection therapy - is used to treat PKU patients aged 16 and over, in whom the blood phenylalanine level is inadequately controlled despite previous treatment with available therapy options (i.e. blood phenylalanine levels> 600 µmol / l).

In healthy people, the Phe level in the blood is below 120 µmol / l. With PKU it is very difficult to get into the normal range. Not only because it is a great challenge to adhere to the strict diet over the long term. “But also because it is always a matter of weighing up,” says Reichert. “How much phenylalanine is too much, how much too little; How do I ensure a balanced supply of other important nutrients as possible despite dieting? ”It's like a tightrope walk.

Adult PKU patients fall through the cracks

Children and young people with PKU are “well looked after” in Germany; The expert knows that there are “enough special pediatric clinics for them”. “For a long time it was assumed that PKU was a childhood disease. It was thought: If those affected stick to the diet at a young age, that's enough. As adults, they don't need any special treatment. ”This has now turned out to be a fallacy:“ The disease requires lifelong therapy. Even adults with too high Phe levels have poor concentration and the like. ”But because the focus was on pediatrics in the past, there is a lack of adult centers today. "If the patients don't live near one of the few specialized centers, they get lost in general medical care."

For “Live Unlimited PKU”, for example, the PKU patient Michelle tells how she looked for help at the age of 25: “I went to all the general practitioners in the area, but was always sent away. I was desperate and miserable. [...] Nobody felt responsible for me. "To be left alone -" that was very bitter. " PKU patient Eva reports something similar: "I have the feeling that as I get older people pay less and less attention." The care situation is becoming more and more confusing: "Which doctor will look after me in the future?" Results? ”Are just two of the many questions that weigh on the young woman. “Between the ages of 18 and 20, I continued to be treated by the pediatrician - although I was already an adult. Now I'm 20 years old and no longer have a doctor. "

Dr. Anja Reichert demands: "Among other things, more doctors should be trained to become metabolism experts and the corresponding services should increasingly be offered at universities and specialized metabolism centers." This is the only way to close the supply gap that arises from the age of 18. The aim must be to make the transition from a children's to an adult center seamless - and to ensure consistent treatment. In addition, uniform treatment and disease management goals are required in every center and access to patient-specific therapy and care from a multidisciplinary team of nutritionists, doctors and psychologists is required for all those affected.


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