The only way to avoid the neurological disorders associated with phenylketonuria is to follow a strict diet. To be effective, this diet must be begun right at the start of life (just after screening).

Phenylalanine is of course an essential amino acid, so a minimum intake is necessary and even compulsory. However, a healthy level in a healthy subject would be a pathological level in a person with an enzyme deficiency.

« With phenylketonuria patients, we speak of tolerance. »

Individual tolerance means adaptation according to the residual activity of the enzyme and of growth :

• 0 - 6 months: 150-250 mg PHE /day (ensuring a minimal intake to begin with)
• 6 months – 5 years: 250-350 mg PHE /day
• 5 ans – adolescence : augmenter la quantité quotidienne progressivement

In phenylketonuria patients, serum phenylalanine should be maintained between 2 and 5 mg/dL (120-300 µmol/L).

Principles of the diet

• Limiting intake of PHE while ensuring minimum requirements are covered from natural foods (fruits and vegetables) using a portion system: 1 portion = 20 mg PHE. Each portion corresponds to a given weight of a fruit or vegetable, and food items are chosen from a list according to the number of portions allowed per day.
• Supplementing with an amino acid mix without PHE, to provide all the other amino acids, vitamins, minerals and trace elements needed for growth (see PhenylAde)
• Monitoring energy intake to ensure it is normal and appropriate for the child’s needs; adding foods that contain only fats or sugars and/or low-protein products (see our boutique)
• Strictly forbidding some foods: meat, fish, preserved meats, dried fruits and vegetables, cereals and cereal products, aspartame.

• Gene therapy is at the animal experimentation stage.
• BH4 (the cofactor essential to the PHE to TYR hydroxylation reaction) may be an alternative solution to the diet, only for patients who are sensitive to BH4 (and not for pregnant women).