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The mainstay of
PKU treatment has
been a lifelong
Phe-restricted diet1,2

Medical Nutrition Therapy (MNT)

Immediately after diagnosis, MNT is initiated to reduce blood Phe concentrations, preventing the development of severe and often irreversible neurological, behavioral, and psychiatric symptoms.3

What’s on the PKU Phe-restricted Plate?3,4

MNT for PKU includes a Phe-restricted diet3,4:
  • Avoidance of high-protein foods, such as animal and dairy products, nuts and seeds, legumes and soy
To maintain energy requirements, patients rely on3:
  • Foods with naturally low protein content
    – Fruits and vegetables
  • Modified low-protein foods from specialized manufacturers
    – Breads and pastas
To replace the intake of natural protein, Phe-free protein substitutes or medical foods are an integral part of MNT3:
  • Helps prevent protein deficiency
  • Ensures the right amount of Phe to function normally, as some Phe is essential
Individual dietary Phe tolerance is influenced by many factors, most importantly5:
  • Severity of PKU
  • Target blood Phe concentrations

Food choices in a given PKU day

Most patients with classic PKU can only tolerate about 5-10g of natural protein to maintain adequate Phe control.6

 

To put this into perspective…

The challenges of adhering to a Phe-restricted diet

The healthcare community generally accepts that dietary management adds significant daily burden to patients and caregivers.9,10

Social pressures make following the diet difficult9

  • Social isolation and stigmatization
  • Shame/embarrassment
  • Decreased emotional well-being
  • Guilt if not/poorly adhering to dietary restrictions

Although studies are limited, adults with PKU can also be prone to disordered eating patterns3,9

  • Preoccupation with food more often than nonadherent patients
  • Disordered dieting behavior
  • Body image issues possibly impeding social functioning and physical health

Limited food choices, cost, and time spent managing diet impact adherence9

  • In an online survey of 631 adults with PKU, 86% of patients (291/338) said significant effort was associated with managing the diet*
  • 14% said they could not manage the diet independently

*Online questionnaire was voluntarily completed and submitted by adults with PKU or parents/caregivers of children or adults unable to complete the survey themselves. The questionnaire was placed on the UK NSPKU website, Facebook, and Twitter accounts between November 9, 2017 and January 31, 2018.

Limited adherence of adult patients to MNT is not always a choice3

In many regions, reimbursement of special manufactured low-protein foods and protein substitutes/medical foods remains an issue3

  • “Suboptimal access to dietary products generates inequality and high out-of-pocket costs”3
  • “When dietary products are insufficiently available, the ability to control blood Phe is beyond the willingness of the patient”
    • “Increases the risk of impaired neurocognitive functioning that can affect employment and socioeconomic status and further limit access to care”3

Despite adhering to a Phe-restricted diet, blood Phe can remain uncontrolled for many adults with PKU11,12

Even among patients who report dietary Phe restriction:

Many can experience elevated blood Phe levels, underscoring the inadequacy of this approach.

Play

Eric: PKU Phe-restricted diet challenges

Hear how Eric overcame Phe-restricted diet challenges
and got back to a new kind of PKU care.

View transcript

Learn more about PKU

Did You Know? The American College of Medical Genetics and Genomics recommends management of PKU for life2

Learn more

References: 1.Rocha JC, MacDonald A. Dietary intervention in the management of phenylketonuria: current perspectives. Pediatric Health Med Ther. 2016;7:155-163. 2. Vockley J, Andersson HC, Antshel KM, et al; American College of Medical Genetics and Genomics Therapeutic Committee. Phenylalanine hydroxylase deficiency: diagnosis and management guidelines. Genet Med. 2014;16(2):188-200. 3. Rocha JC, Ahring KK, Ausel H, et al. Expert consensus on the long-term effectiveness of medical nutrition therapy and its impact on the outcomes of adults with phenylketonuria. Nutrients. 2023;15(18):3940. 4. Lehman S. What to eat when you have PKU. Dietary recommendations for better management. Verywell Health. Updated July 12, 2023. Accessed December 22, 2023. https://www.verywellhealth.com/what-is-the-pku-diet-2507160. 5. van Wegberg AMJ, MacDonald A, Ahring K, et al. The complete European guidelines of phenylketonuria: diagnosis and treatment. Orphanet J Rare Dis. 2017;12(1):162. 6. MacLeod EL, Ney DM. Nutritional management of phenylketonuria. Ann Nestle (Engl) 2010;68:58-69. doi:10:1159/00312813. 7. US Department of Agriculture. Agricultural Research Service/Food Data Central/Food Search. 8. Enns GM, Koch R, Brumm V, Blakely E, Suter R, Jurecki E. Suboptimal outcomes in patients with PKU treated early with diet alone: revisiting the evidence. Mol Genet Metab. 2010;101(2-3):99-109. 9. Ford S, O’Driscoll M, MacDonald A. Living with phenylketonuria: lessons from the PKU community. Mol Genet Metab Rep. 2018;17:57-63. 10. van Spronsen FJ, van Wegberg AMJ, Ahring K, et al. Key European guidelines for the diagnosis and management of patients with phenylketonuria. Lancet Diabetes Endocrinol. 2017;5(9):743-756. 11. Trefz FK, van Spronsen FJ, MacDonald A, et al. Management of adult patients with phenylketonuria survey results from 24 countries. Eur J Pediatr. 2015;174(1):119-127. 12. Levy H, Lamppu D, Anastosoaie V, et al. 5-year retrospective analysis of patients with phenylketonuria (PKU) and hyperphenylalaninemia treated at two specialized clinics. Mol Genet Metab. 2020;129(3):177-185.