Optimising amino acid absorption: essential to improve nitrogen balance and metabolic control in phenylketonuria.
Nutr Res Rev
; 32(1): 70-78, 2019 06.
Article
en En
| MEDLINE
| ID: mdl-30284526
ABSTRACT
It has been nearly 70 years since the discovery that strict adherence to a diet low in phenylalanine prevents severe neurological sequelae in patients with phenylalanine hydroxylase deficiency (phenylketonuria; PKU). Today, dietary treatment with restricted phenylalanine intake supplemented with non-phenylalanine amino acids to support growth and maintain a healthy body composition remains the mainstay of therapy. However, a better understanding is needed of the factors that influence N balance in the context of amino acid supplementation. The aim of the present paper is to summarise considerations for improving N balance in patients with PKU, with a focus on gaining greater understanding of amino acid absorption, disposition and utilisation. In addition, the impact of phenylalanine-free amino acids on 24 h blood phenylalanine/tyrosine circadian rhythm is evaluated. We compare the effects of administering intact protein v. free amino acid on protein metabolism and discuss the possibility of improving outcomes by administering amino acid mixtures so that their absorption profile mimics that of intact protein. Protein substitutes with the ability to delay absorption of phenylalanine and tyrosine, mimicking physiological absorption kinetics, are expected to improve the rate of assimilation into protein and minimise fluctuations in quantitative plasma amino acid levels. They may also help maintain normal glycaemia and satiety sensation. This is likely to play an important role in improving the management of patients with PKU.
Palabras clave
BBB bloodbrain barrier; BH4 tetrahydrobiopterin; GMP glycomacropeptide; LAT1 large neutral amino acid transporter 1; LNAA large neutral amino acid; PAH phenylalanine hydroxylase; PKU phenylketonuria; Phe phenylalanine; Tyr tyrosine; Absorption; Amino acid mixtures; Amino acids; Nitrogen balance; Phenylalanine; Phenylketonuria; Protein synthesis
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Fenilalanina
/
Fenilcetonurias
/
Suplementos Dietéticos
/
Aminoácidos
/
Nitrógeno
Límite:
Humans
Idioma:
En
Revista:
Nutr Res Rev
Asunto de la revista:
CIENCIAS DA NUTRICAO
Año:
2019
Tipo del documento:
Article
País de afiliación:
Reino Unido