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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.
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.
Abstract:
This study aimed to evaluate systematically the effect of the free use of fruits and vegetables containing an intermediate amount of phenylalanine (51-100 mg/100 g) on the biochemical control in children with phenylketonuria (PKU). Fifteen subjects with PKU, with a median age of 6 years (range 1-24 years) were studied. In a three-part prospective 15-week study, subjects sequentially ate fruits and vegetables containing phenylalanine 0-50 mg/100 g for weeks 1 to 3; 51-75 mg/100 g for weeks 4 to 8; and 76-100 mg/100 g for weeks 9 to 15. Plasma phenylalanine concentrations were measured twice daily for three consecutive days in weeks 1, 3, 6, 8, 11, 13 and 15. A standard menu was followed on the blood sampling days. Daily dietary records of fruits and vegetables under study were kept throughout the trial. Control of phenylalanine concentrations was not adversely affected by the free use of fruits and vegetables containing 51-100 mg/100 g. Pre-breakfast median plasma concentrations were: weeks 1 to 3, 260 micromol/L (range 90-890); weeks 4 to 8, 255 micromol/L (range 130-920); and weeks 9 to 15, 278 micromol/L (range 30-880). Pre-evening meal median plasma phenylalanine concentrations were: weeks 1 to 3, 240 micromol/L (range 30-820); weeks 4 to 8, 210 micromol/L (40-880); and weeks 9 to 15, 238 micromol/L (range 20-880). These data suggest that free use of fruits and vegetables containing 51-75 mg/100 g poses no problem for children with PKU.