title: The micronutrient status of patients with phenylketonuria on dietary treatment: an ongoing challenge.
abstract: BACKGROUND
  In phenylketonuria (PKU), phenylalanine-free L-amino acid supplements are the major source of dietary micronutrients.
  
  
  METHODS
  Four hundred fifty-two retrospective annual/bi-annual non-fasting blood samples for nutritional markers (plasma zinc, selenium, and serum folate) from 78 subjects aged 1-16 years (median number of blood samples: 6, range 1-14) were analysed over 12 years. Longitudinal blood result data were available for 51 subjects (65%). The dietary intake from supplements was calculated.
  
  
  RESULTS
  The median intakes of all of the micronutrients studied were >200% of the reference nutrient intakes (RNI). There was no statistical correlation between dietary intake and nutritional markers outside of the normal reference range (RR) except for selenium, but there was a correlation between a lower plasma zinc, plasma selenium and haemoglobin status and better blood phenylalanine control in 1- to 4-year-old children. On at least one occasion, the individual plasma concentrations of zinc (71%, n = 54/76) and selenium (21%, n = 16/75) were below the RR; however, the concentrations of selenium (41%, n = 31/75) and serum folate (83%, n = 34/41) were also above the RR. Dietary intakes exceeded the upper tolerable intakes for zinc and copper (32%, n = 25) and folate (65%, n = 51). Individual longitudinal data demonstrated little change in micronutrient status over time.
  
  
  CONCLUSIONS
  In PKU, biochemical micronutrient deficiencies are common despite micronutrient intakes above the RNI. Further study of the nutritional profiling of L-amino acid supplements in PKU is needed.
authors.affiliation: Birmingham Children's Hospital, Birmingham, UK.
authors.forename: Sharon
authors.initials: S
authors.lastname: Evans
authors.forename: Anne
authors.initials: A
authors.lastname: Daly
authors.forename: John
authors.initials: J
authors.lastname: MacDonald
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Preece
authors.forename: Saikat
authors.initials: S
authors.lastname: Santra
authors.forename: Suresh
authors.initials: S
authors.lastname: Vijay
authors.forename: Anupam
authors.initials: A
authors.lastname: Chakrapani
authors.forename: Anita
authors.initials: A
authors.lastname: MacDonald
mesh_terms: D000293:Adolescent; D000596:Amino Acids / Q000008:administration & dosage; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003300:Copper / Q000097:blood; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000097:blood; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D018977:Micronutrients / Q000008:administration & dosage* / Q000097:blood / Q000172:deficiency*; D009752:Nutritional Status; D010649:Phenylalanine / Q000097:blood; D010661:Phenylketonurias / Q000097:blood / Q000178:diet therapy*; D012189:Retrospective Studies; D012643:Selenium / Q000097:blood; D015032:Zinc / Q000097:blood
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D018977:Micronutrients; D010649:Phenylalanine; D003300:Copper; D005492:Folic Acid; D012643:Selenium; D015032:Zinc