Background: To prevent cognitive impairment, phenylketonuria requires lifelong management of blood phenylalanine (Phe) concentration with a low-Phe diet. The diet restricts intake of Phe from natural proteins in combination with traditional amino acid medical foods (AA-MFs) or glycomacropeptide medical foods (GMP-MFs) that contain primarily intact protein and a small amount of Phe.
Objective: We investigated the efficacy and safety of a low-Phe diet combined with GMP-MFs or AA-MFs providing the same quantity of protein equivalents in free-living subjects with phenylketonuria.
Design: This 2-stage, randomized crossover trial included 30 early-treated phenylketonuria subjects (aged 15-49 y), 20 with classical and 10 with variant phenylketonuria. Subjects consumed, in random order for 3 wk each, their usual low-Phe diet combined with AA-MFs or GMP-MFs. The treatments were separated by a 3-wk washout with AA-MFs. Fasting plasma amino acid profiles, blood Phe concentrations, food records, and neuropsychological tests were obtained.
Results: The frequency of medical food intake was higher with GMP-MFs than with AA-MFs. Subjects rated GMP-MFs as more acceptable than AA-MFs and noted improved gastrointestinal symptoms and less hunger with GMP-MFs. ANCOVA indicated no significant mean ± SE increase in plasma Phe (62 ± 40 μmol/L, P = 0.136), despite a significant increase in Phe intake from GMP-MFs (88 ± 6 mg Phe/d, P = 0.026). AA-MFs decreased plasma Phe (-85 ± 40 μmol/L, P = 0.044) with stable Phe intake. Blood concentrations of Phe across time were not significantly different (AA-MFs = 444 ± 34 μmol/L, GMP-MFs = 497 ± 34 μmol/L), suggesting similar Phe control. Results of the Behavior Rating Inventory of Executive Function were not significantly different.
Conclusions: GMP-MFs provide a safe and acceptable option for the nutritional management of phenylketonuria. The greater acceptability and fewer side effects noted with GMP-MFs than with AA-MFs may enhance dietary adherence for individuals with phenylketonuria. This trial was registered at www.clinicaltrials.gov as NCT01428258.
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| http://dx.doi.org/10.3945/ajcn.116.135293 | DOI Listing |
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Article Synopsis
- In a study on children with Phenylketonuria (PKU), casein glycomacropeptide (GMP) was compared to phenylalanine-free amino acids (AA) as a protein substitute, focusing on digestion and overall health effects.
- Results showed that GMP significantly improved gastrointestinal symptoms like stomach pain and bloating, although it did not have a major impact on other health markers like renal function or oxidative stress.
- However, GMP's higher phenylalanine content poses challenges for use as a sole protein source in PKU kids due to their low tolerance for phenylalanine.
Protein requirements in adults with phenylketonuria and bioavailability of glycomacropeptide compared to an l-amino acid-based product.
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BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
Background: Phenylketonuria (PKU) is caused by phenylalanine hydroxylase deficiency. Treatment is primarily a low-Phe diet combined with l-amino acid-based products (l-AA). Protein requirements in adults with PKU have not been directly determined.
View Article and Find Full Text PDFEvaluation of Body Composition and Biochemical Parameters in Adult Phenylketonuria.
Nutrients
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