The Effect of Glycomacropeptide versus Amino Acids on Phenylalanine and Tyrosine Variability over 24 Hours in Children with PKU: A Randomized Controlled Trial

Daly, Anne, Evans, Sharon, Chahal, Satnam, Santra, Saikat, Pinto, Alex, Gingell, Cerys, Rocha, Julio Cesar, van Spronsen, Francjan, Jackson, Richard and MacDonald, Anita (2019) The Effect of Glycomacropeptide versus Amino Acids on Phenylalanine and Tyrosine Variability over 24 Hours in Children with PKU: A Randomized Controlled Trial. NUTRIENTS, 11 (3). E520-.

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The Effect of Glycomacropeptide versus Amino Acids on Phenylalanine and Tyrosine Variability over 24 Hours in Children with PKU: A Randomized Controlled Trial.pdf - Published version
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Official URL: http://dx.doi.org/10.3390/nu11030520

Abstract

Introduction: In phenylketonuria (PKU), evidence suggests that casein glycomacropeptide supplemented with rate-limiting amino acids (CGMP-AA) is associated with better protein utilisation and less blood phenylalanine (Phe) variability. Aim: To study the impact of CGMP-AA on blood Phe variability using 3 different dietary regimens in children with PKU. Methods: This was a 6-week randomised controlled cross-over study comparing CGMP-AA vs. Phe-free l-amino acids (l-AA) assessing blood Phe and tyrosine (Tyr) variability over 24 h in 19 children (7 boys) with PKU, with a median age of 10 years (6⁻16). Subjects were randomised to 3 dietary regimens: (1) R1, CGMP-AA and usual dietary Phe (CGMP + Phe); (2) R2, CGMP-AA - Phe content of CGMP-AA from usual diet (CGMP - Phe); and (3) R3, l-AA and usual dietary Phe. Each regimen was administered for 14 days. Over the last 48 h on days 13 and 14, blood spots were collected every 4 h at 08 h, 12 h, 16 h, 20 h, 24 h, and 04 h. Isocaloric intake and the same meal plan and protein substitute dosage at standardised times were maintained when blood spots were collected. Results: Eighteen children completed the study. Median Phe concentrations over 24 h for each group were (range) R1, 290 (30⁻580), R2, 220 (10⁻670), R3, 165 (10⁻640) μmol/L. R1 vs. R2 and R1 vs. R3 p < 0.0001; R2 vs. R3 p = 0.0009. There was a significant difference in median Phe at each time point between R1 vs. R2, p = 0.0027 and R1 vs. R3, p < 0.0001, but not between any time points for R2 vs. R3. Tyr was significantly higher in both R1 and R2 [70 (20⁻240 μmol/L] compared to R3 [60 (10⁻200) μmol/L]. In children < 12 years, blood Phe remained in the target range (120⁻360 μmol/L), over 24 h, for 75% of the time in R1, 72% in R2 and 64% in R3; for children aged ≥ 12 years, blood Phe was in target range (120⁻600 μmol/L) in R1 and R2 for 100% of the time, but 64% in R3. Conclusions: The residual Phe in CGMP-AA increased blood Phe concentration in children. CGMP-AA appears to give less blood Phe variability compared to l-AA, but this effect may be masked by the increased blood Phe concentrations associated with its Phe contribution. Reducing dietary Phe intake to compensate for CGMP-AA Phe content may help.

Item Type:	Article
Uncontrolled Keywords:	glycomacropeptide, phenylalanine, phenylketonuria, phenylalanine variability, amino acids, tyrosine
Depositing User:	Symplectic Admin
Date Deposited:	05 Jun 2019 09:03
Last Modified:	24 Jan 2024 20:04
DOI:	10.3390/nu11030520
Open Access URL:	https://doi.org/10.3390/nu11030520
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3044531