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Nutritional therapy in PKU

The important role that diet therapy has in PKU

Phenylketonuria, or PKU, is the most common amino acid disorder.

This kind of pathology implies the deficit or lack of specific enzymes, capable of transforming - metabolising - one or more amino acids. In the case of PKU, it is phenylalanine.

The symptoms of phenylketonuria show when the accumulation, due to consumption of phenylalanine occurs. To avoid this, it is necessary to adapt the patient's diet to the special indications of the metabolic center.

Since the standard treatment of phenylketonuria is purely nutritional, known as diet therapy.

The special diet, outlined to obtain and keep the right levels of phenylalanine in the blood, consists of:


- Natural foods with low protein content such as (in general) fruits and vegetables

- Special low protein foods, marketed by the industry of food for special medical purposes

- Protein substitutes, which provide the patient with the necessary amino acids that they cannot intake through food


Nutritional therapy for PKU has been used successfully since the 1950s.

This means that the patient who is compliant and stays on a diet for life, will not suffer the symptoms of the disease.


The importance of newborn screening lies in the fact that starting the diet from the first weeks of life, the terrible effects of the disorder do not show.

Rapid diagnosis and compliance is the recipe to success in treating phenylketonuria symptoms.


Until a few years ago, the indication of metabolic centers was to continue the special diet only until reaching adulthood, when HCPs believed that, once the psychophysical development phase of the individual was over, it was no longer necessary.

More recently, thanks to the greater amount of data available and feedback on patients, clinical indications have extended the diet to life, to preserve its quality and absence of symptoms.


Alternatives to the diet are drugs – suitable for a limited number of responsive patients and at risk of side effects - and the gene therapy, currently still in an experimental phase.

Only the HCPs can decide if a patient can take another road rather than the diet to treat PKU symptoms.

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