Amino Acid Medical Foods Provide a High Dietary Acid Load and Increase Urinary Excretion of Renal Net Acid, Calcium, and Magnesium Compared with Glycomacropeptide Medical Foods in Phenylketonuria

Background. Skeletal fragility is a complication of phenylketonuria (PKU). A diet containing amino acids compared with glycomacropeptide reduces bone size and strength in mice. Objective. We tested the hypothesis that amino acid medical foods (AA-MF) provide a high dietary acid load, subsequently in...

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Bibliographic Details
Published in:Journal of nutrition and metabolism 2017-01, Vol.2017 (2017), p.1-12
Main Authors: Hansen, Karen E., Binkley, Neil, Murali, Sangita G., Sawin, Emily A., Stroup, Bridget M., Ney, Denise M.
Format: Article
Language:English
Subjects:
Amino acids
Bioavailability
Bone density
Calcium
Care and treatment
Clinical Study
Clinical trials
Complications and side effects
Diet
Dietary minerals
Endocrinology
Food
Functional foods
Load
Magnesium
Medicine
Metabolism
Nutritional aspects
Phenylketonuria
Physiological aspects
Proteins
Public health
Rodents
Studies
Urine
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Summary:Background. Skeletal fragility is a complication of phenylketonuria (PKU). A diet containing amino acids compared with glycomacropeptide reduces bone size and strength in mice. Objective. We tested the hypothesis that amino acid medical foods (AA-MF) provide a high dietary acid load, subsequently increasing urinary excretion of renal net acid, calcium, and magnesium, compared to glycomacropeptide medical foods (GMP-MF). Design. In a crossover design, 8 participants with PKU (16–35 y) provided food records and 24-hr urine samples after consuming a low-Phe diet in combination with AA-MF and GMP-MF for 1–3 wks. We calculated potential renal acid load (PRAL) of AA-MF and GMP-MF and determined bone mineral density (BMD) measurements using dual X-ray absorptiometry. Results. AA-MF provided 1.5–2.5-fold higher PRAL and resulted in 3-fold greater renal net acid excretion compared to GMP-MF (p=0.002). Dietary protein, calcium, and magnesium intake were similar. GMP-MF significantly reduced urinary excretion of calcium by 40% (p=0.012) and magnesium by 30% (p=0.029). Two participants had low BMD-for-age and trabecular bone scores, indicating microarchitectural degradation. Urinary calcium with AA-MF negatively correlated with L1–L4 BMD. Conclusion. Compared to GMP-MF, AA-MF increase dietary acid load, subsequently increasing urinary calcium and magnesium excretion, and likely contributing to skeletal fragility in PKU. The trial was registered at clinicaltrials.gov as NCT01428258.
ISSN:2090-0724
2090-0732
DOI:10.1155/2017/1909101