Dietary Management Of Phenylketonuria: Causes And Symptoms

Phenylketonuria is a rare inherited condition which causes amino acid phenylalanine to accumulate in the body. The condition develops due to a defect in the gene which creates the enzyme required to break down phenylalanine.

In the absence of this enzyme, a hazardous build up develops when one consumes foods high in protein.

This can eventually lead to serious health problems.

Signs And Symptoms Of Phenylketonuria

Newborns with phenylketonuria initially have no clinical manifestations. Without treatment, babies develop signs in a couple of months. Signs and symptoms of phenylketonuria include:

  • Delayed development in children.
  • Emotional, behavioral and social issues.
  • Psychiatric disorders
  • Abnormally small head
  • Intellectual disability
  • Neurological problems
  • Reduced bone strength
  • Eczema
  • Musty smell in the breath, skin or urine, due to large amounts of phenylalanine in the body.
  • Fair skin and blue eyes, (phenylalanine cannot get converted into melanin which is responsible for hair and skin color).

What Causes Phenylketonuria?

A genetic mutation causes phenylketonuria. The defective gene is responsible for an insufficiency of the enzyme which is required to process the amino acid phenylalanine.

The condition is autosomal recessive and for a child to develop phenylketonuria, both the parents need to pass on the defective gene.

If only one parent has the phenylketonuria gene, then there is no risk of passing on the condition to the offspring, but it is likely that the child could be a carrier.

Dietary Treatment Of Phenylketonuria

  • It is very vital that you discuss the condition in detail with your health care provider as well as nutritionist. A lifetime diet comprising of very little intake of protein, since foods rich in protein contain phenylalanine.
  • Taking a PKU formula, a nutritional supplement to ensure you get adequate essential protein (without phenylalanine)
  • Your health care provider will assess and review your diet records, growth charts and blood levels of phenylalanine and make necessary changes; thus follow-ups are crucial.
  • You need to avoid all high protein foods – milk, cheese, soy, legumes, eggs, chicken, beans, beef, pork, and fish. Talk with your doctor or dietician to learn about your specific dietary requirements.
  • Formula for babies needs to be prescribed. Breast milk and regular infant formula contain phenylalanine; hence, these individuals need to consume a phenylalanine-free formula. A nutritionist will work out a carefully planned amount of breast milk or regular formula to be blended in with the phenylalanine-free formula. Solid foods with little phenylalanine are given to children after discussing with the dietician.
  • Formula for older children and adults comprises of a protein substitute formula to be had every day, as told to you by your health care provider. The daily dose of formula is divided between meals and not consumed all at once.
  • Some health care providers advise a supplement – neutral amino acid therapy. This supplement blocks some absorption of phenylalanine. On the other hand, this is an emerging therapy option and hasn’t been well-studied.
  • Families need to commit to this lifestyle alteration sincerely since this is the only way to thwart serious health issues which people with phenylketonuria are known to develop.
  • The Food and Drug Administration has approved the drug sapropterin to deal with phenylketonuria. This drug helps increase your tolerance to phenylalanine. The drug is to be used in combination with a phenylketonouria diet.