Overweight in Phenylketonuria

Phenylketonuria (PKU; MIM 261600) is an inborn error of amino acid metabolism caused by reduced phenylalanine hydroxylase (PAH; EC 1.14.16.1) activity (Blau et al 2010). After the discover by Dr. Asbjørn Følling (Folling 1994), the first treatment approach was proposed by Dr. Horst Bickel in 1950s (Bickel et al 1953). Despite new therapies have recently emerged [large neutral amino acids (LNAA), Glycomacropeptide (GMP) and Sapropterin (BH4)] (Ney et al 2014), the proposed dietary phenylalanine (Phe) restriction is still the mainstay of treatment for patients with PKU. This is achieved through a natural protein restricted diet giving simultaneously a Phe-free amino acid mixture (protein substitute), nowadays enriched with vitamins and minerals (Giovannini et al 2012). In order to satisfy patient’s energy needs and to improve dietary compliance, special low protein foods are currently available for inclusion in the diet. The nutritional composition of these foods reveals a significant richness in carbohydrates and fat, while protein and Phe content are almost negligible (Rocha et al 2007).