Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria

Phenylalanine (Phe) tolerance is highly variable in phenylketonuria (PKU) and rarely described in patients aged ≥12 years. Patients ≥12 years of age with PKU were systematically challenged with additional natural protein (NP) if blood Phe levels remained below 480 µmol/L (i.e., upper target blood Ph...

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Main Authors: Alex Pinto, Manuela Ferreira Almeida, Anita MacDonald, Paula Cristina Ramos, Sara Rocha, Arlindo Guimas, Rosa Ribeiro, Esmeralda Martins, Anabela Bandeira, Richard Jackson, Francjan van Spronsen, Anne Payne, Júlio César Rocha
Format: Article
Language:English
Published: MDPI AG 2019-04-01
Series:Nutrients
Subjects:
BH4
Online Access:https://www.mdpi.com/2072-6643/11/5/995
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spelling doaj-9c528025ee344e3cb46282c547fa7e712020-11-25T01:33:14ZengMDPI AGNutrients2072-66432019-04-0111599510.3390/nu11050995nu11050995Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in PhenylketonuriaAlex Pinto0Manuela Ferreira Almeida1Anita MacDonald2Paula Cristina Ramos3Sara Rocha4Arlindo Guimas5Rosa Ribeiro6Esmeralda Martins7Anabela Bandeira8Richard Jackson9Francjan van Spronsen10Anne Payne11Júlio César Rocha12Faculty of Health &amp; Human Sciences, University of Plymouth, Plymouth PL6 8BH, UKCentro de Genética Médica, Centro Hospitalar Universitário do Porto (CHUP), 4099-028 Porto, PortugalBirmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UKCentro de Genética Médica, Centro Hospitalar Universitário do Porto (CHUP), 4099-028 Porto, PortugalCentro de Referência na área de Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto-CHUP, 4099-001 Porto, PortugalCentro de Referência na área de Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto-CHUP, 4099-001 Porto, PortugalCentro de Referência na área de Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto-CHUP, 4099-001 Porto, PortugalCentro de Referência na área de Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto-CHUP, 4099-001 Porto, PortugalCentro de Referência na área de Doenças Hereditárias do Metabolismo, Centro Hospitalar Universitário do Porto-CHUP, 4099-001 Porto, PortugalCancer Research UK Liverpool Cancer Trials Unit, University of Liverpool, Liverpool L69 3GL, UKBeatrix Children’s Hospital, University Medical Center Groningen, University of Groningen, 9713 Groningen, The NetherlandsFaculty of Health &amp; Human Sciences, University of Plymouth, Plymouth PL6 8BH, UKCentro de Genética Médica, Centro Hospitalar Universitário do Porto (CHUP), 4099-028 Porto, PortugalPhenylalanine (Phe) tolerance is highly variable in phenylketonuria (PKU) and rarely described in patients aged ≥12 years. Patients ≥12 years of age with PKU were systematically challenged with additional natural protein (NP) if blood Phe levels remained below 480 µmol/L (i.e., upper target blood Phe level for patients aged ≥12 years using Portuguese PKU guidelines). In PKU patients, NP tolerance was calculated at baseline and a median of 6 months after systematic challenge with NP whilst patients were maintaining a blood Phe ≤480 μmol/L. Anthropometry was assessed at both times. Routine blood Phe levels were collected. We studied 40 well-controlled PKU patients (10 hyperphenylalaninemia (HPA), 23 mild and 7 classic PKU), on a low-Phe diet with a mean age of 17 years (12–29 years). Median daily NP intake significantly increased between assessments (35 vs. 40 g/day, <i>p</i> = 0.01). Twenty-six patients (65%) were able to increase their median NP intake by a median 12 g/day (2–42 g)/day and still maintain blood Phe within target range. Out of the previous 26 patients, 20 (77%) (8 HPA, 11 mild and 1 classical PKU) increased NP from animal sources (e.g., dairy products, fish and meat) and 6 patients (23%) (3 mild and 3 classical PKU) from plant foods (bread, pasta, potatoes). Median protein equivalent intake from Phe-free/low-Phe protein substitute decreased (0.82 vs. 0.75 g/kg, <i>p</i> = 0.01), while median blood Phe levels remained unchanged (279 vs. 288 μmol/L, <i>p</i> = 0.06). Almost two-thirds of patients with PKU tolerated additional NP when challenged and still maintained blood Phe within the national target range. This suggests that some patients with PKU treated by a low-Phe diet only may over restrict their NP intake. In order to minimise the burden of treatment and optimise NP intake, it is important to challenge with additional NP at periodic intervals.https://www.mdpi.com/2072-6643/11/5/995BH4natural protein tolerancephenylketonuriaphenylalanine
collection DOAJ
language English
format Article
sources DOAJ
author Alex Pinto
Manuela Ferreira Almeida
Anita MacDonald
Paula Cristina Ramos
Sara Rocha
Arlindo Guimas
Rosa Ribeiro
Esmeralda Martins
Anabela Bandeira
Richard Jackson
Francjan van Spronsen
Anne Payne
Júlio César Rocha
spellingShingle Alex Pinto
Manuela Ferreira Almeida
Anita MacDonald
Paula Cristina Ramos
Sara Rocha
Arlindo Guimas
Rosa Ribeiro
Esmeralda Martins
Anabela Bandeira
Richard Jackson
Francjan van Spronsen
Anne Payne
Júlio César Rocha
Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
Nutrients
BH4
natural protein tolerance
phenylketonuria
phenylalanine
author_facet Alex Pinto
Manuela Ferreira Almeida
Anita MacDonald
Paula Cristina Ramos
Sara Rocha
Arlindo Guimas
Rosa Ribeiro
Esmeralda Martins
Anabela Bandeira
Richard Jackson
Francjan van Spronsen
Anne Payne
Júlio César Rocha
author_sort Alex Pinto
title Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
title_short Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
title_full Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
title_fullStr Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
title_full_unstemmed Over Restriction of Dietary Protein Allowance: The Importance of Ongoing Reassessment of Natural Protein Tolerance in Phenylketonuria
title_sort over restriction of dietary protein allowance: the importance of ongoing reassessment of natural protein tolerance in phenylketonuria
publisher MDPI AG
series Nutrients
issn 2072-6643
publishDate 2019-04-01
description Phenylalanine (Phe) tolerance is highly variable in phenylketonuria (PKU) and rarely described in patients aged ≥12 years. Patients ≥12 years of age with PKU were systematically challenged with additional natural protein (NP) if blood Phe levels remained below 480 µmol/L (i.e., upper target blood Phe level for patients aged ≥12 years using Portuguese PKU guidelines). In PKU patients, NP tolerance was calculated at baseline and a median of 6 months after systematic challenge with NP whilst patients were maintaining a blood Phe ≤480 μmol/L. Anthropometry was assessed at both times. Routine blood Phe levels were collected. We studied 40 well-controlled PKU patients (10 hyperphenylalaninemia (HPA), 23 mild and 7 classic PKU), on a low-Phe diet with a mean age of 17 years (12–29 years). Median daily NP intake significantly increased between assessments (35 vs. 40 g/day, <i>p</i> = 0.01). Twenty-six patients (65%) were able to increase their median NP intake by a median 12 g/day (2–42 g)/day and still maintain blood Phe within target range. Out of the previous 26 patients, 20 (77%) (8 HPA, 11 mild and 1 classical PKU) increased NP from animal sources (e.g., dairy products, fish and meat) and 6 patients (23%) (3 mild and 3 classical PKU) from plant foods (bread, pasta, potatoes). Median protein equivalent intake from Phe-free/low-Phe protein substitute decreased (0.82 vs. 0.75 g/kg, <i>p</i> = 0.01), while median blood Phe levels remained unchanged (279 vs. 288 μmol/L, <i>p</i> = 0.06). Almost two-thirds of patients with PKU tolerated additional NP when challenged and still maintained blood Phe within the national target range. This suggests that some patients with PKU treated by a low-Phe diet only may over restrict their NP intake. In order to minimise the burden of treatment and optimise NP intake, it is important to challenge with additional NP at periodic intervals.
topic BH4
natural protein tolerance
phenylketonuria
phenylalanine
url https://www.mdpi.com/2072-6643/11/5/995
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