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Free use of fruits and vegetables in phenylketonuria

A MacDonald1, G Rylance, P Davies

  • 1The Children's Hospital, Steelhouse Lane, Birmingham, UK.

Journal of Inherited Metabolic Disease
|September 16, 2003
PubMed

Insights

Children with phenylketonuria (PKU) can safely consume fruits and vegetables with moderate phenylalanine levels. This study found that including these foods did not negatively impact biochemical control in pediatric PKU patients.

Area of Science:

  • Biochemistry
  • Pediatrics
  • Nutrition Science

Background:

  • Phenylketonuria (PKU) is a genetic disorder requiring strict phenylalanine restriction.
  • Dietary management of PKU often limits fruits and vegetables due to their phenylalanine content.
  • Assessing the impact of intermediate phenylalanine foods is crucial for improving dietary adherence and quality of life.

Purpose of the Study:

  • To systematically evaluate the effect of free consumption of fruits and vegetables with intermediate phenylalanine levels (51-100 mg/100 g) on biochemical control in children with PKU.
  • To determine if these foods adversely affect plasma phenylalanine concentrations in pediatric PKU patients.
  • To provide evidence-based dietary recommendations for managing PKU.

Main Methods:

  • A prospective, 15-week study involving 15 children with PKU (median age 6 years).
  • Subjects consumed fruits and vegetables with increasing phenylalanine content (0-50, 51-75, and 76-100 mg/100 g) over three sequential periods.
  • Plasma phenylalanine concentrations were measured bi-daily on specific days, with standard menus and daily dietary records maintained.

Main Results:

  • Plasma phenylalanine control was not adversely affected by the free use of fruits and vegetables containing 51-100 mg/100 g.
  • Median pre-breakfast plasma phenylalanine levels ranged from 260 to 278 micromol/L across study phases.
  • Median pre-evening meal plasma phenylalanine levels ranged from 210 to 240 micromol/L across study phases.

Conclusions:

  • The free use of fruits and vegetables containing 51-75 mg/100 g poses no problem for biochemical control in children with PKU.
  • These findings suggest that dietary guidelines for PKU can be liberalized to include a wider variety of fruits and vegetables.
  • This can potentially improve nutritional intake and adherence to the PKU diet.

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