Dietary intervention in the management of phenylketonuria: current perspectives
- PMID: 29388626
- PMCID: PMC5683291
- DOI: 10.2147/PHMT.S49329
Dietary intervention in the management of phenylketonuria: current perspectives
Abstract
Phenylketonuria (PKU) is a well-described inborn error of amino acid metabolism that has been treated for >60 years. Enzyme deficiency causes accumulation of phenylalanine (Phe) and if left untreated will lead to profound and irreversible intellectual disability in most children. Traditionally, it has been managed with a low-Phe diet supplemented with a Phe-free protein substitute although newer treatment options mainly in combination with diet are available for some subgroups of patients with PKU, for example, sapropterin, large neutral amino acids, and glycomacropeptide. The diet consists of three parts: 1) severe restriction of dietary Phe; 2) replacement of non-Phe l-amino acids with a protein substitute commonly supplemented with essential fatty acids and other micronutrients; and 3) low-protein foods from fruits, some vegetables, sugars, fats and oil, and special low-protein foods (SLPF). The prescription of diet is challenging for health professionals. The high-carbohydrate diet supplied by a limited range of foods may program food preferences and contribute to obesity in later life. Abnormal tasting and satiety-promoting protein substitutes are administered to coincide with peak appetite times to ensure their consumption, but this practice may impede appetite for other important foods. Intermittent dosing of micronutrients when combined with l-amino acid supplements may lead to their poor bioavailability. Much work is required on the ideal nutritional profiling for special SLPF and Phe-free l-amino acid supplements. Although non-diet treatments are being studied, it is important to continue to fully understand all the consequences of diet therapy as it is likely to remain the foundation of therapy for many years.
Keywords: PKU; glycomacropeptide; l-amino acids; large neutral amino acids; phenylalanine; sapropterin.
Conflict of interest statement
Disclosure Júlio César Rocha has received research grants from Cambrooke. He is a member of the European Nutritionist Expert Panel in PKU (ENEP), for which he has received consultancy fees from Merck Serono and BioMarin. He is also a member of the Advisory Board for Applied Pharma Research SA (APR). Anita MacDonald has received research grants from Nutricia, Vitaflo, Merck Serono, BioMarin, Metax, and Taranis. She is a member of the European Nutritionist Expert Panel in PKU (ENEP), for which she has received consultancy fees from Merck Serono and BioMarin and is a member of the European Phenylketonuria Group Advisory Board (EPG; formally Merck Serono and now BioMarin), and the Advisory Boards for Element (Nutricia), Arla Foods and APR. The authors report no other conflicts of interest in this work.
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