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Pinto A, Ilgaz F, Evans S, van Dam E, Rocha JC, Karabulut E, Hickson M, Daly A, MacDonald A. Phenylalanine Tolerance over Time in Phenylketonuria: A Systematic Review and Meta-Analysis. Nutrients 2023; 15:3506. [PMID: 37630696 PMCID: PMC10458574 DOI: 10.3390/nu15163506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
In phenylketonuria (PKU), natural protein tolerance is defined as the maximum natural protein intake maintaining a blood phenylalanine (Phe) concentration within a target therapeutic range. Tolerance is affected by several factors, and it may differ throughout a person's lifespan. Data on lifelong Phe/natural protein tolerance are limited and mostly reported in studies with low subject numbers. This systematic review aimed to investigate how Phe/natural protein tolerance changes from birth to adulthood in well-controlled patients with PKU on a Phe-restricted diet. Five electronic databases were searched for articles published until July 2020. From a total of 1334 results, 37 articles met the eligibility criteria (n = 2464 patients), and 18 were included in the meta-analysis. The mean Phe (mg/day) and natural protein (g/day) intake gradually increased from birth until 6 y (at the age of 6 months, the mean Phe intake was 267 mg/day, and natural protein intake was 5.4 g/day; at the age of 5 y, the mean Phe intake was 377 mg/day, and the natural protein intake was 8.9 g/day). However, an increase in Phe/natural protein tolerance was more apparent at the beginning of late childhood and was >1.5-fold that of the Phe tolerance in early childhood. During the pubertal growth spurt, the mean natural protein/Phe tolerance was approximately three times higher than in the first year of life, reaching a mean Phe intake of 709 mg/day and a mean natural protein intake of 18 g/day. Post adolescence, a pooled analysis could only be performed for natural protein intake. The mean natural protein tolerance reached its highest (32.4 g/day) point at the age of 17 y and remained consistent (31.6 g/day) in adulthood, but limited data were available. The results of the meta-analysis showed that Phe/natural protein tolerance (expressed as mg or g per day) increases with age, particularly at the beginning of puberty, and reaches its highest level at the end of adolescence. This needs to be interpreted with caution as limited data were available in adult patients. There was also a high degree of heterogeneity between studies due to differences in sample size, the severity of PKU, and target therapeutic levels for blood Phe control.
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Affiliation(s)
- Alex Pinto
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (S.E.); (A.D.); (A.M.)
- School of Health Professions, Faculty of Health, University of Plymouth, Plymouth PL4 6AB, UK;
| | - Fatma Ilgaz
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Hacettepe University, 06100 Ankara, Turkey;
| | - Sharon Evans
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (S.E.); (A.D.); (A.M.)
| | - Esther van Dam
- Beatrix Children’s Hospital, University of Groningen, University Medical Center, 9700 RB Groningen, The Netherlands;
| | - Júlio César Rocha
- Nutrition and Metabolism, NOVA Medical School, Faculdade de Ciencias Medicas, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal;
- CINTESIS@RISE, NOVA Medical School, Faculdade de Ciências Médicas, NMS, FCM, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal
- Reference Centre of Inherited Metabolic Diseases, Centro Hospitalar Universitario de Lisboa Central, 1169-045 Lisboa, Portugal
| | - Erdem Karabulut
- Department of Biostatistics, Faculty of Medicine, Hacettepe University, 06100 Ankara, Turkey;
| | - Mary Hickson
- School of Health Professions, Faculty of Health, University of Plymouth, Plymouth PL4 6AB, UK;
| | - Anne Daly
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (S.E.); (A.D.); (A.M.)
| | - Anita MacDonald
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (S.E.); (A.D.); (A.M.)
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Saleemani H, Egri C, Horvath G, Stockler‐Ipsiroglu S, Elango R. Dietary management and growth outcomes in children with propionic acidemia: A natural history study. JIMD Rep 2021; 61:67-75. [PMID: 34485020 PMCID: PMC8411103 DOI: 10.1002/jmd2.12234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Propionic acidemia (PROP) is an autosomal recessive inherited deficiency of propionyl-CoA carboxylase (PCC) which is involved in the catalytic breakdown of the amino acids valine, isoleucine, methionine, and threonine. PROP nutritional management is based on dietary protein restriction and use of special medical formulas which are free of the offending amino acids, but are enriched in leucine. The resulting imbalance among branched-chain amino acids negatively impacts plasma concentrations of valine and isoleucine, which might impact growth in children with PROP. OBJECTIVE AND METHODS Our primary objective was to describe dietary protein and calorie intake and their impact on long-term growth outcomes of four PROP patients. This was accomplished through a longitudinal retrospective chart review following the cohort from birth to 18 years. RESULTS All children (n = 4) had poor growth outcomes with persistently reduced height-for-age Z scores, and elevated weight and body mass index (BMI) Z scores. Energy intakes for all subjects were within 80% to 120% of the dietary reference intakes for age. All children had low intakes of intact protein compared with current guidelines and were supplemented with medical formula and single l-amino acids (valine and/or isoleucine), which led to the excess consumption of total protein. CONCLUSION Despite adequate total protein and energy intakes, all children had persistently low height Z scores. Restricted intact protein consumption together with the abundant use of medical formula could have affected overall growth. To optimize dietary management in patients with PROP, further research is needed to determine the optimal intake of medical formula relative to intact protein.
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Affiliation(s)
- Haneen Saleemani
- BC Children's Hospital Research Institute, BC Children's HospitalVancouverBritish ColumbiaCanada
- Faculty of Land and Food SystemsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Faculty of Applied Medical Sciences, Department of Clinical NutritionKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Csilla Egri
- Division of Biochemical GeneticsBC Children's HospitalVancouverBritish ColumbiaCanada
- Department of PediatricsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Gabriella Horvath
- Division of Biochemical GeneticsBC Children's HospitalVancouverBritish ColumbiaCanada
- Department of PediatricsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Sylvia Stockler‐Ipsiroglu
- BC Children's Hospital Research Institute, BC Children's HospitalVancouverBritish ColumbiaCanada
- Division of Biochemical GeneticsBC Children's HospitalVancouverBritish ColumbiaCanada
- Department of PediatricsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Rajavel Elango
- BC Children's Hospital Research Institute, BC Children's HospitalVancouverBritish ColumbiaCanada
- Faculty of Land and Food SystemsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of PediatricsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- School of Population and Public Health, University of British ColumbiaVancouverBritish ColumbiaCanada
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Ilgaz F, Marsaux C, Pinto A, Singh R, Rohde C, Karabulut E, Gökmen-Özel H, Kuhn M, MacDonald A. Protein Substitute Requirements of Patients with Phenylketonuria on BH4 Treatment: A Systematic Review and Meta-Analysis. Nutrients 2021; 13:1040. [PMID: 33807079 PMCID: PMC8004763 DOI: 10.3390/nu13031040] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/12/2021] [Accepted: 03/19/2021] [Indexed: 11/16/2022] Open
Abstract
The traditional treatment for phenylketonuria (PKU) is a phenylalanine (Phe)-restricted diet, supplemented with a Phe-free/low-Phe protein substitute. Pharmaceutical treatment with synthetic tetrahydrobiopterin (BH4), an enzyme cofactor, allows a patient subgroup to relax their diet. However, dietary protocols guiding the adjustments of protein equivalent intake from protein substitute with BH4 treatment are lacking. We systematically reviewed protein substitute usage with long-term BH4 therapy. Electronic databases were searched for articles published between January 2000 and March 2020. Eighteen studies (306 PKU patients) were eligible. Meta-analyses demonstrated a significant increase in Phe and natural protein intakes and a significant decrease in protein equivalent intake from protein substitute with cofactor therapy. Protein substitute could be discontinued in 51% of responsive patients, but was still required in 49%, despite improvement in Phe tolerance. Normal growth was maintained, but micronutrient deficiency was observed with BH4 treatment. A systematic protocol to increase natural protein intake while reducing protein substitute dose should be followed to ensure protein and micronutrient requirements are met and sustained. We propose recommendations to guide healthcare professionals when adjusting dietary prescriptions of PKU patients on BH4. Studies investigating new therapeutic options in PKU should systematically collect data on protein substitute and natural protein intakes, as well as other nutritional factors.
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Affiliation(s)
- Fatma Ilgaz
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Hacettepe University, 06100 Ankara, Turkey; (F.I.); (H.G.-Ö.)
| | - Cyril Marsaux
- Danone Nutricia Research, 3584CT Utrecht, The Netherlands;
| | - Alex Pinto
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (A.P.); (A.M.)
| | - Rani Singh
- Metabolic Genetics Nutrition Program, Department of Human Genetics, Emory University, Atlanta, GA 30322, USA;
| | - Carmen Rohde
- Department of Paediatrics of the University Clinics Leipzig, University of Leipzig, 04103 Leipzig, Germany;
| | - Erdem Karabulut
- Department of Biostatistics, Faculty of Medicine, Hacettepe University, 06100 Ankara, Turkey;
| | - Hülya Gökmen-Özel
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Hacettepe University, 06100 Ankara, Turkey; (F.I.); (H.G.-Ö.)
| | - Mirjam Kuhn
- Danone Nutricia Research, 3584CT Utrecht, The Netherlands;
| | - Anita MacDonald
- Department of Dietetics, Birmingham Women’s and Children’s Hospital, Birmingham B4 6NH, UK; (A.P.); (A.M.)
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