Improved nutritional management of phenylketonuria by using a diet containing glycomacropeptide compared with amino acids
Open Access
- 1 April 2009
- journal article
- research article
- Published by Oxford University Press (OUP) in The American Journal of Clinical Nutrition
- Vol. 89 (4), 1068-1077
- https://doi.org/10.3945/ajcn.2008.27280
Abstract
Background: Phenylketonuria (PKU) requires a lifelong low-phenylalanine diet that provides the majority of protein from a phenylalanine-free amino acid (AA) formula. Glycomacropeptide (GMP), an intact protein formed during cheese production, contains minimal phenylalanine. Objective: The objective was to investigate the effects of substituting GMP food products for the AA formula on acceptability, safety, plasma AA concentrations, and measures of protein utilization in subjects with PKU. Design: Eleven subjects participated in an inpatient metabolic study with two 4-d treatments: a current AA diet (AA diet) followed by a diet that replaced the AA formula with GMP (GMP diet) supplemented with limiting AAs. Plasma concentrations of AAs, blood chemistries, and insulin were measured and compared in AA (day 4) and GMP diets (day 8). Results: The GMP diet was preferred to the AA diet in 10 of 11 subjects with PKU, and there were no adverse reactions to GMP. There was no significant difference in phenylalanine concentration in postprandial plasma with the GMP diet compared with the AA diet. When comparing fasting with postprandial plasma, plasma phenalyalanine concentration increased significantly with the AA but not with the GMP diet. Blood urea nitrogen was significantly lower, which suggests decreased ureagenesis, and plasma insulin was higher with the GMP diet than with the AA diet. Conclusions: GMP, when supplemented with limiting AAs, is a safe and highly acceptable alternative to synthetic AAs as the primary protein source in the nutritional management of PKU. As an intact protein source, GMP improves protein retention and phenylalanine utilization compared with AAs.Keywords
This publication has 40 references indexed in Scilit:
- l-Arginine and tetrahydrobiopterin protects against ischemia/reperfusion-induced endothelial dysfunction in patients with type 2 diabetes mellitus and coronary artery diseaseAtherosclerosis, 2009
- Nutritional management of PKU with glycomacropeptide from cheese wheyJournal of Inherited Metabolic Disease, 2008
- Adaptation to a long term (4weeks) arginine- and precursor (glutamate, proline and aspartate)-free dietClinical Nutrition, 2008
- Acceptable low-phenylalanine foods and beverages can be made with glycomacropeptide from cheese whey for individuals with PKUMolecular Genetics and Metabolism, 2007
- The effects of large neutral amino acid supplements in PKU: An MRS and neuropsychological studyMolecular Genetics and Metabolism, 2007
- Double blind placebo control trial of large neutral amino acids in treatment of PKU: Effect on blood phenylalanineJournal of Inherited Metabolic Disease, 2007
- Large neutral amino acids block phenylalanine transport into brain tissue in patients with phenylketonuriaJCI Insight, 1999
- Mutational spectrum of phenylalanine hydroxylase deficiency in Sicily: implications for diagnosis of hyperphenyl-alaninemia in Southern EuropeHuman Molecular Genetics, 1993
- Contribution of Postprandial Amino Acid Levels to Stimulation of Insulin, Glucagon, and Pancreatic Polypeptide in HumansPancreas, 1992
- Effect of Simultaneous Ingestion of L‐Amino Acids and Whole Protein on Plasma Amino Acid and Urea Nitrogen Concentrations in HumansJournal of Parenteral and Enteral Nutrition, 1991