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Advances in Phenylketonuria (PKU) Nutrition and Diet Research

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A special issue of Nutrients (ISSN 2072-6643). This special issue belongs to the section "Nutritional Epidemiology".

Deadline for manuscript submissions: closed (25 June 2023) | Viewed by 22560

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Special Issue Editors

Prof. Dr. Júlio César Rocha

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Guest Editor

1. NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade NOVA de Lisboa, Lisboa, Portugal
2. Reference Centre of Inherited Metabolic Diseases, Centro Hospitalar Universitário de Lisboa Central, Lisboa, Portugal
3. CINTESIS@RISE, Nutrition and Metabolism, NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade NOVA de Lisboa, Lisboa, Portugal
Interests: inherited metabolic diseases; nutrition; dietetics; metabolism; nutritional status
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Anita MacDonald

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Guest Editor

Dietetic Department, Birmingham Children's Hospital, Steelhouse Lane, Birmingham B4 6NH, UK
Interests: phenylketonuria; dietary treatment; protein substitutes; dietary adherence; feeding development
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It has been 70 years since the introduction of the first successful dietary therapy for a child with phenylketonuria (PKU) at Birmingham’s Children Hospital, UK. Even though the initial synthetic phenylalanine (Phe)-restricted diet was unpalatable and very abnormal compared to a regular diet, its impact on improving blood Phe metabolic control was clear. It is remarkable that after so many decades the principles of the nutritional management rely on the same approach, particularly in patients who are not candidates for alternative pharmacological therapies. Advancing and comprehensive knowledge of molecular genetics indicates that PKU is a condition that can be managed by a personalized therapeutic approach using pharmaceutical treatment options, usually in combination with dietary treatments. This has introduced many challenging questions about the real impact of new therapies on dietary patterns, food choices, nutritional status and the development of co-morbidities in patients with PKU. There are also several areas of dietary management that remain unclear or unchallenged. We underline the importance of health professionals collecting routine systematic data in patients with PKU in order to fully understand all aspects of treatment impact instead of spending countless hours debating unknown and controversial aspects of care. Meta-analyses and systematic reviews are very good opportunities to methodologically summarize current scientific evidence, helping to guide clinical practice and open new avenues for targeted research. We warmly challenge and invite our colleagues to engrain research practices into all aspects of training and clinical activities. Only in this way can we gain robust data that will improve clinical treatment practices and patient care. Although we do not close the door to experimental research, we do expect this Special Issue to specifically promote all current Advances in Phenylketonuria (PKU) Nutrition and Dietetic Research.

Prof. Dr. Júlio César Rocha
Prof. Dr. Anita MacDonald
Guest Editors

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Keywords

phenylketonuria
nutrition
metabolism
nutritional status
diet
body composition
dietetics
nutrition psychology
feeding development
childhood nutrition
disordered eating

Published Papers (12 papers)

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13 pages, 1228 KiB

Open AccessArticle

Evaluation of a New ‘Mix-In’ Style Glycomacropeptide-Based Protein Substitute for Food and Drinks in Patients with Phenylketonuria and Tyrosinemia

by Marta Delsoglio, Rebecca Capener, Anita MacDonald, Anne Daly, Catherine Ashmore, Sarah Donald, Lisa Gaff, Louise VanDorp, Rachel Skeath, Charlotte Ellerton, Camille Newby, Georgina Dunning, Clare Dale, Inderdip Hunjan, Lucy White, Heather Allen, Gary P. Hubbard and Rebecca J. Stratton

Nutrients 2023, 15(16), 3598; https://doi.org/10.3390/nu15163598 - 17 Aug 2023

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Abstract

(1) Background: Poor palatability, large volume, and lack of variety of some liquid and powdered protein substitutes (PSs) for patients with phenylketonuria (PKU) and tyrosinemia (TYR) can result in poor adherence. This study aimed to evaluate a new unflavoured, powdered GMP-based PS designed to be mixed into drinks, foods, or with other PSs, in patients with PKU and TYR. (2) Methods: Paediatric and adult community-based patients were recruited from eight metabolic centres and prescribed ≥1 sachet/day (10 g protein equivalent (PE)) of the Mix-In-style PS over 28 days. Adherence, palatability, GI tolerance, and metabolic control were recorded at baseline and follow-up. Patients who completed at least 7 days of intervention were included in the final analysis. (3) Results: Eighteen patients (3–45 years, nine males) with PKU (n = 12) and TYR (n = 6) used the Mix-In-style PS for ≥7 days (mean 26.4 days (SD 4.6), range 11–28 days) alongside their previous PS, with a mean intake of 16.7 g (SD 7.7) PE/day. Adherence was 86% (SD 25), and GI tolerance was stable, with n = 14 experiencing no/no new symptoms and n = 3 showing improved symptoms compared to baseline. Overall palatability was rated satisfactory by 78% of patients, who successfully used the Mix-In-style PS in various foods and drinks, including smoothies, squash, and milk alternatives, as a top-up to meet their protein needs. There was no concern regarding safety/metabolic control during the intervention. (4) Conclusions: The ‘Mix-In’-style PS was well adhered to, accepted, and tolerated. Collectively, these data show that providing a flexible, convenient, and novel format of PS can help with adherence and meet patients’ protein needs. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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14 pages, 1513 KiB

Open AccessArticle

Evaluation of a New Glycomacropeptide-Based Protein Substitute in Powdered and Liquid Format in Patients with PKU

by Marta Delsoglio, Rebecca Capener, Anita MacDonald, Anne Daly, Catherine Ashmore, Charlotte Ellerton, Sarah Donald, Lisa Gaff, Louise VanDorp, Rachel Skeath, Camille Newby, Georgina Dunning, Clare Dale, Inderdip Hunjan, Lucy White, Heather Allen, Gary P. Hubbard and Rebecca J. Stratton

Nutrients 2023, 15(16), 3580; https://doi.org/10.3390/nu15163580 - 14 Aug 2023

Viewed by 1041

Abstract

(1) Background: Good adherence to a Phe-restricted diet supplemented with an adequate amount of a protein substitute (PS) is important for good clinical outcomes in PKU. Glycomacropeptide (cGMP)-PSs are innovative, palatable alternatives to amino acid-based PSs (AA-PS). This study aimed to evaluate a new cGMP-PS in liquid and powder formats in PKU. (2) Methods: Children and adults with PKU recruited from eight centres were prescribed at least one serving/day of cGMP-PS for 7–28 days. Adherence, acceptability, and gastrointestinal tolerance were recorded at baseline and the end of the intervention. The blood Phe levels reported as part of routine care during the intervention were recorded. (3) Results: In total, 23 patients (powder group, n = 13; liquid group, n = 10) completed the study. The majority assessed the products to be palatable (77% of powder group; 100% of liquid group) and well tolerated; the adherence to the product prescription was good. A total of 14 patients provided blood Phe results during the intervention, which were within the target therapeutic range for most patients (n = 11) at baseline and during the intervention. (4) Conclusions: These new cGMP-PSs were well accepted and tolerated, and their use did not adversely affect blood Phe control. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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12 pages, 289 KiB

Open AccessArticle

Amino Acid Analyses of Plant Foods Used in the Dietary Management of Inherited Amino Acid Disorders

by Suzanne Ford, Fatma Ilgaz, Sarah Hawker, Barbara Cochrane, Melanie Hill, Charlotte Ellerton and Anita MacDonald

Nutrients 2023, 15(10), 2387; https://doi.org/10.3390/nu15102387 - 19 May 2023

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Abstract

A low amino acid (AA)/protein diet is the principal treatment for many inherited amino acid disorders (IMDs). Due to their low AA content, plant foods constitute an essential part of diet therapy. However, data on their AA composition are limited, which leads to an estimation of AA intake from protein content rather than an accurate calculation of true AA intake. This study describes the AA content of a total of 73 plant foods (fruits, n = 12; vegetables, n = 51; and other plant foods, n = 10), with the analysis commissioned by the UK National Society for Phenylketonuria (NSPKU) over 15 years. For all fruits and some vegetables (e.g., rocket, watercress and pea shoots), raw samples were used during analysis. All other vegetables were cooked prior to analysis to represent the usual condition of the food at the time of serving. AA analysis was performed with ion exchange chromatography. The median percentage of protein was 2.0% [0.6–5.4%] for the fruits and vegetables analysed (n = 56), although higher in vegetables than in fruits. Each of the five reported AAs (leucine, lysine, phenylalanine, tyrosine, and methionine) supplied 1–5% per g of protein content. From the heterogeneous range of plant foods analysed, the AA/protein ratios differed significantly (2–5% in fruits and 1–9% in vegetables). There was a strong correlation between the amounts of each of the five AAs in the plant foods, but only a small, moderate correlation between the protein and AA content. Overall, this study provides data on the AA content of several plant foods, which are suitable for patients treated with a low AA/protein diet, including many novel plant options. However, only a limited range of fruits and vegetables were analysed due to the high costs of analysis. Hence, more extensive studies with an increased number of plant foods prepared by different cooking methods and replicate samples are necessary, particularly to examine the relationship between the protein and AA content in depth. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

15 pages, 997 KiB

Open AccessArticle

Parent’s Perception of the Types of Support Given to Families with an Infant with Phenylketonuria

by Sophie Cassidy, Sharon Evans, Alex Pinto, Anne Daly, Catherine Ashmore, Suzanne Ford, Sharon Buckley and Anita MacDonald

Nutrients 2023, 15(10), 2328; https://doi.org/10.3390/nu15102328 - 16 May 2023

Viewed by 1441

Abstract

Background: A diagnosis of phenylketonuria (PKU) in an infant is a devastating and overwhelming event for their parents. Providing appropriate information and support is paramount, especially at the beginning of a child’s life. Investigating if parents are receiving the right support is important for continued care. Methodology: An online survey was distributed to explore parents’ perceptions of current support and information provided by their healthcare provider and to rate sources of other support (n = 169 participants). Results: Dietitians received the highest (85%) rate of “very helpful” support. Overall, parents found Facebook to be helpful for support but had mixed reactions when asked if healthcare professionals (HCPs) should provide advice as part of the groups. When rating the most effective learning methods, the top three were 1:1 teaching sessions (n = 109, 70%), picture books (n = 73, 50%), and written handouts (n = 70, 46%). Conclusion: Most parents are happy with the support and information they receive from their dietitian but required more support from other HCPs. Facebook groups provide parents with the social support that HCPs and their family may be unable to offer, suggesting a place for social media in future PKU care. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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15 pages, 4746 KiB

Open AccessArticle

The BMI Z-Score and Protein Energy Ratio in Early- and Late-Diagnosed PKU Patients from a Single Reference Center in Mexico

by Lizbeth Alejandra López-Mejía, Cynthia Fernández-Lainez, Marcela Vela-Amieva, Isabel Ibarra-González and Sara Guillén-López

Nutrients 2023, 15(4), 957; https://doi.org/10.3390/nu15040957 - 14 Feb 2023

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Abstract

The relationship between protein and energy and their appropriate proportions in hyperphenylalaninemia (HPA) or phenylketonuria (PKU) patients in terms of growth have been poorly studied, especially in those diagnosed late. We aimed to describe the protein energy ratio (P:E) and its association with body mass index (BMI) in 638 dietetic and anthropometric assessments from 54 early- or late-diagnosed HPA/PKU patients. Dietetic and anthropometric data were analyzed and classified according to BMI Z-Score and type of diagnosis, early by newborn screening (NBS) or late. Correlation between BMI Z-Score and P:E ratio was established. Percent of dietary protein from Phe-free metabolic formula was analyzed. According to the BMI Z-Score, the majority of assessments were eutrophic (69.4%). The median P:E ratio was >4 in most of the overweight assessments. Remarkably, the underweight group consumed the highest proportion of Phe-free metabolic formula (74.5%). A positive correlation between BMI Z-Score and P:E ratio was found. The highest proportion of underweight was found in the late-diagnosed patients. Our findings might be related to their nutritional history previous to the HPA/PKU treatment. Thus, complex nutritional outcome of the late-diagnosed HPA/PKU patients deserves actions to guarantee the early diagnosis, closer nutritional follow-up and alternative therapeutic approaches. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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16 pages, 831 KiB

Open AccessArticle

Suitability and Allocation of Protein-Containing Foods According to Protein Tolerance in PKU: A 2022 UK National Consensus

by Maria Inês Gama, Sarah Adam, Sandra Adams, Heather Allen, Catherine Ashmore, Sarah Bailey, Barbara Cochrane, Clare Dale, Anne Daly, Giana De Sousa, Sarah Donald, Carolyn Dunlop, Charlotte Ellerton, Sharon Evans, Sarah Firman, Suzanne Ford, Francine Freedman, Moira French, Lisa Gaff, Joanna Gribben, Anne Grimsley, Ide Herlihy, Melanie Hill, Farzana Khan, Nicola McStravick, Chloe Millington, Nicola Moran, Camille Newby, Patty Nguyen, Janet Purves, Alex Pinto, Júlio César Rocha, Rachel Skeath, Amy Skelton, Simon Tapley, Alison Woodall, Carla Young and Anita MacDonald Show full author list Hide full author list

Nutrients 2022, 14(23), 4987; https://doi.org/10.3390/nu14234987 - 24 Nov 2022

Cited by 4 | Viewed by 2104

Abstract

Introduction: There is little practical guidance about suitable food choices for higher natural protein tolerances in patients with phenylketonuria (PKU). This is particularly important to consider with the introduction of adjunct pharmaceutical treatments that may improve protein tolerance. Aim: To develop a set of guidelines for the introduction of higher protein foods into the diets of patients with PKU who tolerate >10 g/day of protein. Methods: In January 2022, a 26-item food group questionnaire, listing a range of foods containing protein from 5 to >20 g/100 g, was sent to all British Inherited Metabolic Disease Group (BIMDG) dietitians (n = 80; 26 Inherited Metabolic Disease [IMD] centres). They were asked to consider within their IMD dietetic team when they would recommend introducing each of the 26 protein-containing food groups into a patient’s diet who tolerated >10 g to 60 g/day of protein. The patient protein tolerance for each food group that received the majority vote from IMD dietetic teams was chosen as its tolerance threshold for introduction. A virtual meeting was held using Delphi methodology in March 2022 to discuss and agree final consensus. Results: Responses were received from dietitians from 22/26 IMD centres (85%) (11 paediatric, 11 adult). For patients tolerating protein ≥15 g/day, the following foods were agreed for inclusion: gluten-free pastas, gluten-free flours, regular bread, cheese spreads, soft cheese, and lentils in brine; for protein tolerance ≥20 g/day: nuts, hard cheeses, regular flours, meat/fish, and plant-based alternative products (containing 5–10 g/100 g protein), regular pasta, seeds, eggs, dried legumes, and yeast extract spreads were added; for protein tolerance ≥30 g/day: meat/fish and plant-based alternative products (containing >10–20 g/100 g protein) were added; and for protein tolerance ≥40 g/day: meat/fish and plant-based alternatives (containing >20 g/100 g protein) were added. Conclusion: This UK consensus by IMD dietitians from 22 UK centres describes for the first time the suitability and allocation of higher protein foods according to individual patient protein tolerance. It provides valuable guidance for health professionals to enable them to standardize practice and give rational advice to patients. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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17 pages, 1174 KiB

Open AccessArticle

Impact of Fruit and Vegetable Protein vs. Milk Protein on Metabolic Control of Children with Phenylketonuria: A Randomized Crossover Controlled Trial

by Alex Pinto, Anne Daly, Júlio César Rocha, Catherine Ashmore, Sharon Evans, Richard Jackson, Anne Payne, Mary Hickson and Anita MacDonald

Nutrients 2022, 14(20), 4268; https://doi.org/10.3390/nu14204268 - 13 Oct 2022

Cited by 4 | Viewed by 2035

Abstract

Fruits and vegetables containing phenylalanine ≤ 75 mg/100 g (except potatoes) have little impact on blood phenylalanine in phenylketonuria (PKU). In a randomized, controlled, crossover intervention trial, we examined the effect of increasing phenylalanine intake from fruits and vegetables, containing phenylalanine 76–100 mg /100 g, compared with milk protein sources on blood phenylalanine control. This was a five-phase study (4 weeks each phase). In Phase A, patients remained on their usual diet and then were randomly allocated to start Phase B and C (an additional phenylalanine intake of 50 mg/day, then 100 mg from fruits and vegetables containing phenylalanine 76–100 mg/100 g) or Phase D and E (an additional phenylalanine intake of 50 mg/day then 100 mg/day from milk sources). There was a 7-day washout with the usual phenylalanine-restricted diet between Phase B/C and D/E. Blood phenylalanine was measured on the last 3 days of each week. If four out of six consecutive blood phenylalanine levels were >360 μmol/L in one arm, this intervention was stopped. Sixteen patients (median age 10.5 y; range 6–12 y) were recruited. At baseline, a median of 6 g/day (range: 3–25) natural protein and 60 g/day (range: 60–80) protein equivalent from protein substitute were prescribed. Median phenylalanine levels were: Phase A—240 μmol/L; Phase B—260 μmol/L; Phase C—280 μmol/L; Phase D—270 μmol/L and Phase E—280 μmol/L. All patients tolerated an extra 50 mg/day of phenylalanine from fruit and vegetables, containing phenylalanine 76–100 mg/100 g, but only 11/16 (69%) tolerated an additional 100 mg /day. With milk protein, only 8/16 (50%) tolerated an extra 50 mg/day and only 5/16 (31%) tolerated an additional 100 mg/day of phenylalanine. Tolerance was defined as maintaining consistent blood phenylalanine levels < 360 μmol/L throughout each study arm. There was a trend that vegetable protein had less impact on blood phenylalanine control than milk protein, but overall, the differences were not statistically significant (p = 0.152). This evidence supports the PKU European Guidelines cutoff that fruit and vegetables containing 76–100 mg phenylalanine/100 g should be calculated as part of the phenylalanine exchange system. Tolerance of the ‘free use’ of these fruits and vegetables depends on inter-patient variability but cannot be recommended for all patients with PKU. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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9 pages, 652 KiB

Open AccessArticle

Breastfeeding in Phenylketonuria: Changing Modalities, Changing Perspectives

by Juri Zuvadelli, Sabrina Paci, Elisabetta Salvatici, Federica Giorgetti, Graziella Cefalo, Alice Re Dionigi, Valentina Rovelli and Giuseppe Banderali

Nutrients 2022, 14(19), 4138; https://doi.org/10.3390/nu14194138 - 5 Oct 2022

Cited by 4 | Viewed by 2507

Abstract

Phenylketonuria (PKU) management aims to control phenylalanine (Phe) intakes. In newborns and infants this implies possible titration of Human milk (HM) with supplementation of Phe-free formula. HM benefits, better if prolonged, are well known in healthy populations, suggesting it may be used in PKU patients. Despite that, the current literature does not define recommendations on how best perform it in such a population. The main purpose of this study was to evaluate nutrition approaches in newborns and infants affected by PKU and to define if differences can influence the duration of breastfeeding. Data from 42 PKU infants were reviewed. Of these, 67% were breastfed with the use of three different approaches. The type of approach used impacted the duration of breastfeeding, which was longer when using a pre-measured amount of Phe-free formula administered prior to HM. This is the first study to suggest a specific method for breastfeeding in PKU. Considering widely known breastfeeding benefits, both for patients and their mothers, our data should encourage adequate awareness on how to choose correct breastfeeding modalities. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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9 pages, 241 KiB

Open AccessArticle

Communication of an Abnormal Metabolic New-Born Screening Result in The Netherlands: The Parental Perspective

by Sietske Haitjema, Charlotte M. A. Lubout, Justine H. M. Zijlstra, Bruce H. R. Wolffenbuttel and Francjan J. van Spronsen

Nutrients 2022, 14(19), 3961; https://doi.org/10.3390/nu14193961 - 23 Sep 2022

Cited by 1 | Viewed by 1234

Abstract

In the Netherlands, abnormal New-Born Screening (NBS) results are communicated to parents by the general practitioner (GP). Good communication and consequential trust in professionals is of the utmost importance in the treatment of phenylketonuria (PKU). The aim of this study was to assess parental satisfaction regarding the communication of an abnormal NBS result for PKU in the Netherlands. An email containing the link to a web-based questionnaire was sent by the Dutch PKU Association to their members. Responses to open questions were categorized, data of both open and closed questions were analysed with descriptive statistics and the Chi-Square test using SPSS. Out of 113 parents of a child with PKU (born between 1979 and 2020), 68 stated they were overall unsatisfied with the first communication of the NBS result. Seventy-five parents indicated that wrong or no information about PKU was given. A significant decrease was found in the number of parents being contact by their own GP over the course of 40 years (p < 0.05). More than half of all parents were overall unsatisfied with the first communication of the abnormal NBS result for PKU. Further research on how to optimize communication of an abnormal NBS results is necessary. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

14 pages, 4864 KiB

Open AccessArticle

Glycomacropeptide Safety and Its Effect on Gut Microbiota in Patients with Phenylketonuria: A Pilot Study

by Chiara Montanari, Camilla Ceccarani, Antonio Corsello, Juri Zuvadelli, Emerenziana Ottaviano, Michele Dei Cas, Giuseppe Banderali, Gianvincenzo Zuccotti, Elisa Borghi and Elvira Verduci

Nutrients 2022, 14(9), 1883; https://doi.org/10.3390/nu14091883 - 29 Apr 2022

Cited by 18 | Viewed by 2685

Abstract

Glycomacropeptide (GMP) represents a good alternative protein source in Phenylketonuria (PKU). In a mouse model, it has been suggested to exert a prebiotic role on beneficial gut bacteria. In this study, we performed the 16S rRNA sequencing to evaluate the effect of 6 months of GMP supplementation on the gut microbiota of nine PKU patients, comparing their bacterial composition and clinical parameters before and after the intervention. GMP seems to be safe from both the microbiological and the clinical point of view. Indeed, we did not observe dramatic changes in the gut microbiota but a specific prebiotic effect on the butyrate-producer Agathobacter spp. and, to a lesser extent, of Subdoligranulum. Clinically, GMP intake did not show a significant impact on both metabolic control, as phenylalanine values were kept below the age target and nutritional parameters. On the other hand, an amelioration of calcium phosphate homeostasis was observed, with an increase in plasmatic vitamin D and a decrease in alkaline phosphatase. Our results suggest GMP as a safe alternative in the PKU diet and its possible prebiotic role on specific taxa without causing dramatic changes in the commensal microbiota. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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Review

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10 pages, 932 KiB

Open AccessReview

A Retrospective Chart Review and Infant Feeding Survey in the Irish Phenylketonuria (PKU) Population (2016–2020)

by Jane Rice, Jenny McNulty, Meabh O’Shea, Teresa Gudex and Ina Knerr

Nutrients 2023, 15(15), 3380; https://doi.org/10.3390/nu15153380 - 29 Jul 2023

Viewed by 1242

Abstract

Phenylketonuria (PKU) is an inherited disorder of protein metabolism. It is generally treated using dietary management with limited intake of phenylalanine (Phe). Partial breastfeeding (BF) is encouraged among mothers of infants with PKU, together with a Phe-free mixture of synthetic amino acids. Our aim was to describe our current BF rates and complementary feeding practices, as well as examining parental experiences of infant feeding. The objective was to better understand the challenges faced by families so that improvements can be made to clinical care. A chart review was carried out on 39 PKU patients, examining the BF rate and duration, use of second stage synthetic protein (SP), and average complementary feeding age. A parental questionnaire on complementary feeding and BF experience was designed: 26% of babies were partially breastfed at three months of age; 70% of mums would like to have breastfed for longer and cited PKU as a reason for stopping; 52% of parents reported challenges during the complementary feeding process including food refusal, protein calculation, and anxiety around maintaining good Phe levels. Suggestions to improve BF continuation and duration include active promotion of the benefits and suitability, access to lactation consultant, and peer support. The delay in introducing a second stage SP may contribute to long-term bottle use for SP. Improved patient education, written resources, and support is necessary to improve food choices and long-term acceptance of SP. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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Other

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17 pages, 724 KiB

Open AccessSystematic Review

Dietary Liberalization in Tetrahydrobiopterin-Treated PKU Patients: Does It Improve Outcomes?

by Roeland A. F. Evers, Annemiek M. J. van Wegberg, Anita MacDonald, Stephan C. J. Huijbregts, Vincenzo Leuzzi and Francjan J. van Spronsen

Nutrients 2022, 14(18), 3874; https://doi.org/10.3390/nu14183874 - 19 Sep 2022

Cited by 3 | Viewed by 2039

Abstract

Purpose: this systematic review aimed to assess the effects of dietary liberalization following tetrahydrobiopterin (BH₄) treatment on anthropometric measurements, nutritional biomarkers, quality of life, bone density, mental health and psychosocial functioning, and burden of care in PKU patients. Methods: the PubMed, Cochrane, and Embase databases were searched on 7 April 2022. We included studies that reported on the aforementioned domains before and after dietary liberalization as a result of BH₄ treatment in PKU patients. Exclusion criteria were: studies written in a language other than English; studies that only included data of a BH₄ loading test; insufficient data for the parameters of interest; and wrong publication type. Both within-subject and between-subject analyses were assessed, and meta-analyses were performed if possible. Results: twelve studies containing 14 cohorts and 228 patients were included. Single studies reported few significant differences. Two out of fifteen primary meta-analyses were significant; BMI was higher in BH₄-treated patients versus controls (p = 0.02; standardized mean difference (SMD) (95% confidence interval (CI)) = −0.37 (−0.67, −0.06)), and blood cholesterol concentrations increased after starting BH₄ treatment (p = 0.01; SMD (CI) = −0.70 (−1.26, −0.15)). Conclusion: there is no clear evidence that dietary liberalization after BH₄ treatment has a positive effect on anthropometric measurements, nutritional biomarkers, or quality of life. No studies could be included for bone density, mental health and psychosocial functioning, and burden of care. Full article

(This article belongs to the Special Issue Advances in Phenylketonuria (PKU) Nutrition and Diet Research)

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