Natural Protein Tolerance and Metabolic Control in Patients with Hereditary Tyrosinaemia Type 1

Yilmaz, Özlem; Daly, Anne; Pinto, Alex; Ashmore, Catherine; Evans, Sharon; Gupte, Girish; Santra, Saikat; Preece, Mary Anne; McKiernan, Patrick; Kitchen, Steve; Ayhan, Nurcan Yabancı; MacDonald, Anita

doi:10.3390/nu12041148

Cited by 6 publications

(9 citation statements)

References 32 publications

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“…A nationwide study from Finland reported low median adult heigh z-scores in both transplanted and NTBC-treated subjects [ 31 ]. In contrast, a retrospective study from Birmingham showed an improvement in height z-scores from 8 years of age, reaching population standards by 16 years of age [ 32 ].…”

Section: Discussionmentioning

confidence: 99%

Casein Glycomacropeptide: An Alternative Protein Substitute in Tyrosinemia Type I

et al. 2021

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Tyrosinemia type I (HTI) is treated with nitisinone, a tyrosine (Tyr) and phenylalanine (Phe)-restricted diet, and supplemented with a Tyr/Phe-free protein substitute (PS). Casein glycomacropeptide (CGMP), a bioactive peptide, is an alternative protein source to traditional amino acids (L-AA). CGMP contains residual Tyr and Phe and requires supplementation with tryptophan, histidine, methionine, leucine, cysteine and arginine. Aims: a 2-part study assessed: (1) the tolerance and acceptability of a low Tyr/Phe CGMP-based PS over 28 days, and (2) its long-term impact on metabolic control and growth over 12 months. Methods: 11 children with HTI were recruited and given a low Tyr/Phe CGMP to supply all or part of their PS intake. At enrolment, weeks 1 and 4, caregivers completed a questionnaire on gastrointestinal symptoms, acceptability and ease of PS use. In study part 1, blood Tyr and Phe were assessed weekly; in part 2, weekly to fortnightly. In parts 1 and 2, weight and height were assessed at the study start and end. Results: Nine of eleven children (82%), median age 15 years (range 8.6–17.7), took low Tyr/Phe CGMP PS over 28 days; it was continued for 12 months in n = 5 children. It was well accepted by 67% (n = 6/9), tolerated by 100% (n = 9/9) and improved gastrointestinal symptoms in 2 children. The median daily dose of protein equivalent from protein substitute was 60 g/day (range 45–60 g) with a median of 20 g/day (range 15 to 30 g) from natural protein. In part 2 (n = 5), a trend for improved blood Tyr was observed: 12 months pre-study, median Tyr was 490 μmol/L (range 200–600) and Phe 50 μmol/L (range 30–100); in the 12 months taking low Tyr/Phe CGMP PS, median Tyr was 430 μmol/L (range 270–940) and Phe 40 μmol/L (range 20–70). Normal height, weight and BMI z scores were maintained over 12 months. Conclusions: In HTI children, CGMP was well tolerated, with no deterioration in metabolic control or growth when studied over 12 months. The efficacy of CGMP in HTI needs further investigation to evaluate the longer-term impact on blood Phe concentrations and its potential influence on gut microflora

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Section: Discussionmentioning

confidence: 99%

Casein Glycomacropeptide: An Alternative Protein Substitute in Tyrosinemia Type I

et al. 2021

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“…Therefore, the main focus should be on increasing compliance to achieve improved metabolic control rather than further restricting food choices. Protein tolerance has been shown to increase with age which argues in favor of a simplified and relaxed diet especially in adolescents and adults [14].…”

Section: Discussionmentioning

confidence: 99%

“…This would also avoid significant age differences between relaxed and strict diet groups. Age can be a confounder in terms of protein tolerance [14] and compliance.…”

Section: Discussionmentioning

confidence: 99%

Hepatorenal Tyrosinaemia: Impact of a Simplified Diet on Metabolic Control and Clinical Outcome

et al. 2020

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Background: Tyrosinaemia type 1 is a rare inherited metabolic disease caused by an enzyme defect in the tyrosine degradation pathway. It is treated using nitisinone and a low-protein diet. In a workshop in 2013, a group of nutritional specialists from Germany, Switzerland and Austria agreed to advocate a simplified low-protein diet and to allow more natural protein intake in patients with tyrosinaemia type 1. This retrospective study evaluates the recommendations made at different treatment centers and their impact on clinical symptoms and metabolic control. Methods: For this multicenter study, questionnaires were sent to nine participating treatment centers to collect data on the general therapeutic approach and data of 47 individual patients treated by those centers. Results: Dietary simplification allocating food to 3 categories led to increased tyrosine and phenylalanine blood concentrations without weighing food. Phenylalanine levels were significantly higher in comparison to a strict dietary regimen whereas tyrosine levels in plasma did not change. Non-inferiority was shown for the simplification and liberalization of the diet. Compliance with dietary recommendations was higher using the simplified diet in comparison to the stricter approach. Age correlates negatively with compliance. Conclusions: Simplification of the diet with increased natural protein intake based on three categories of food may be implemented in the diet of patients with tyrosinaemia type 1 without significantly altering metabolic control. Patient compliance is strongly influencing tyrosine blood concentrations. A subsequent prospective study with a larger sample size is necessary to get a better insight into the effect of dietary recommendations on metabolic control.

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“…Data on phenylalanine supplementation was also collected. The dietary management in our centre has been previously described [ 19 ].…”

Section: Methodsmentioning

confidence: 99%

“…Despite considerable experience with dietary treatment in HTI, precise nutritional requirements are not well-defined. It has been reported that patients with HTI tolerate more natural protein with increasing age without compromising metabolic control [ 19 , 20 ]. In PKU, there is some evidence to suggest that maximizing natural protein intake may improve height growth and body composition parameters [ 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Physical Growth of Patients with Hereditary Tyrosinaemia Type I: A Single-Centre Retrospective Study

et al. 2021

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In a retrospective review, we aimed to assess long-term growth in 17 patients (n = 11 males) with hereditary tyrosinaemia type I (HTI). Median age at assessment was 15.6 years (5.7–26.6 years) and median age at diagnosis was 1 month (range: 0–16 months), with 35% (n = 6/17) symptomatic on presentation. From the age of 8 years, there was a noticeable change in median height, weight, and body-mass-index [BMI]-z-scores. Median height-for-age z-scores were consistently ≤ −1 (IQR −1.6, −0.5) during the first 8 years of life but increased with age. Weight-for-age z-scores ranged between −1 to 0 (IQR −1.2, 0.1) in the first 8 years; then increased to > 0.5 (IQR −0.3, 1.3) by age 16 years, and BMI-for-age z-scores ranged from 0 to 1 (IQR −0.7, 1.3) up to 8 years, and >1 (IQR −0.2, 1.9) until 16 years. The percentage of overweight and obesity was lowest in children aged < 5 years, and consistently > 40% in patients aged between 7 to 16 years. The prescribed total protein intake was associated with improved height growth (p < 0.01). Impaired growth in early life improved with age achieving normal population standards. Further studies are needed to investigate factors that influence growth outcome in HTI patients.

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Natural Protein Tolerance and Metabolic Control in Patients with Hereditary Tyrosinaemia Type 1

Cited by 6 publications

References 32 publications

Casein Glycomacropeptide: An Alternative Protein Substitute in Tyrosinemia Type I

Casein Glycomacropeptide: An Alternative Protein Substitute in Tyrosinemia Type I

Hepatorenal Tyrosinaemia: Impact of a Simplified Diet on Metabolic Control and Clinical Outcome

Physical Growth of Patients with Hereditary Tyrosinaemia Type I: A Single-Centre Retrospective Study

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