Simplified diet for nutrition management of phenylketonuria: A survey of u.s. metabolic dietitians

Joyanna Hansen, Suzanne Hollander, Nicoletta Drilias, Sandra Van Calcar, Fran Rohr, Laurie Bernstein

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Background: Phenylketonuria (PKU) is an inherited metabolic disorder affecting the conversion of phenylalanine (Phe) to tyrosine. Medical nutrition therapy, consisting of a Phe-restricted diet with medical formula, is the primary treatment for PKU. The Simplified Diet is an approach to PKU nutrition management that allows certain fruits, vegetables, and low-protein foods to be eaten without measuring or tracking, referred to as free/uncounted foods. There is no consensus on how to implement this approach in metabolic centers in the United States (U.S.), and clinical practice varies. Aim: This study describes the clinical experience of metabolic dietitians in U.S.-based metabolic centers related to the use and implementation of the Simplified Diet. Methods: A survey was developed and sent out to metabolic dietitians to query current clinical practices related to the Simplified Diet. Descriptive statistics were used to analyze responses. Results: Sixty-three dietitians managing ≥5 patients with PKU in U.S.-based metabolic centers responded to the survey. Ninety-eight percent of survey respondents reported using some version of the Simplified Diet in clinical practice. The survey identified areas of strong agreement, including introduction of the Simplified Diet at 6 to 12 months of age. The survey also identified areas of widespread variability, including specific Phe or protein thresholds for free/ uncounted foods, and whether or not to set daily quantity limits on these foods. Conclusions: Significant variability related to implementation of the Simplified Diet exists across U.S.-based metabolic centers. This practice variability may contribute to differences in the patient experience across centers and may indicate a need for development of clinical guidelines.

Original languageEnglish (US)
Pages (from-to)83-89
Number of pages7
JournalJIMD Reports
Issue number1
StatePublished - May 2020


  • Dietitian
  • Metabolic
  • PKU
  • Phenylketonuria
  • Simplified diet

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)


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