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BACKGROUND/OBJECTIVES: Protein substitutes (PS) are an essential component in the dietary management of phenylketonuria (PKU). PS are available as phenylalanine-free amino-acid mixtures (AAM), glycomacropeptide-based PS (GMP) and large neutral amino acids (LNAA). There is a lack of information regarding their availability in different countries and comparison of their nutritional composition is limited. The objectives of this study were to identify the number of PS available in different European countries and Turkey and to compare their nutritional composition. SUBJECTS/METHODS: Members of the European Nutritionist Expert Panel on PKU (ENEP) (Portugal, Spain, Belgium, Italy, Germany, Netherlands, United Kingdom, Denmark and Turkey) provided data on PS available in each country. The nutritional composition of PS available in Portugal was analyzed. RESULTS: The number of PS available in each country varied from 30 (Turkey) to 105 (Germany), with a median of 64. GMP was available only in Portugal, whereas LNAA was an option in Portugal, Italy, Turkey and Denmark. Some PS were designed for weaning. Many PS did not contain added fat and fiber. GMP contained the highest carbohydrate (CHO) and energy content as well as higher LNAA content compared with AAM. Only one AAM contained added fructo-oligosaccharides and galacto-oligosaccharides. AAM designed for the first year of life had the highest CHO, fat and LNAA contribution. Liquid AAM had lower CHO and fat contents compared with powdered AAM, but contained higher LNAA. CONCLUSIONS: There was widely dissimilar numbers of PS available in different countries. Nutritional composition of different PS was variable and should be considered before prescription. European Journal of Clinical Nutrition (2016) 70, 785-789; doi: 10.1038/ejcn.2016.54; published online 27 April 2016, INTRODUCTION Nutritional treatment of patients with phenylketonuria (PKU) involves the restriction of phenylalanine (Phe), found in natural protein-containing foods, in combination with a protein replacement/substitute without Phe. Protein substitutes (PS) [...]

Background: Severe intellectual disability and growth impairment have been overcome by the success of early and continuous treatment of patients with phenylketonuria (PKU). However, there are some reports of obesity, particularly in women, suggesting that this may be an important comorbidity in PKU. It is becoming evident that in addition to acceptable blood phenylalanine control, metabolic dieticians should regard weight management as part of routine clinical practice., Summary: It is important for practitioners to differentiate the 3 levels for overweight interpretation: anthropometry, body composition and frequency and severity of associated metabolic comorbidities. The main objectives of this review are to suggest proposals for the minimal standard and gold standard for the assessment of weight management in PKU. While the former aims to underline the importance of nutritional status evaluation in every specialized clinic, the second objective is important in establishing an understanding of the breadth of overweight and obesity in PKU in Europe., Key Messages: In PKU, the importance of adopting a European nutritional management strategy on weight management is highlighted in order to optimize long-term health outcomes in patients with PKU., (© 2015 S. Karger AG, Basel.)

Background: Special low protein foods (SLPF) are essential in the nutritional management of patients with phenylketonuria (PKU). The study objectives were to: 1) identify the number of SLPF available for use in eight European countries and Turkey and 2) analyse the nutritional composition of SLPF available in one of these countries., Methods: European Nutritionist Expert Panel on PKU (ENEP) members (Portugal, Spain, Belgium, Italy, Germany, Netherlands, UK, Denmark and Turkey) provided data on SPLF available in each country. The nutritional composition of Portuguese SLPF was compared with regular food products., Results: The number of different SLPF available in each country varied widely with a median of 107 [ranging from 73 (Portugal) and 256 (Italy)]. Food analysis of SLPF available from a single country (Portugal) indicated that the mean phenylalanine content was higher in low protein baby cereals (mean 48 mg/100 g) and chocolate/energy bars/jelly (mean 41 mg/100 g). The energy content of different foods from a sub-group of SLPF (cookies) varied widely between 23 and 96 kcal/cookie. Low protein bread had a high fat content [mean 5.8 g/100 g (range 3.7 to 10)] compared with 1.6 g/100 g in regular bread. Seven of the 12 SLPF sub-groups (58 %) did not declare any vitamin content, and only 4 (33 %) identified a limited number of minerals., Conclusions: Whilst equal and free access to all SLPF is desirable, the widely variable nutritional composition requires careful nutritional knowledge of all products when prescribed for individual patients with PKU. There is a need for more specific nutritional standards for special low protein foods.

Patients with phenylketonuria (PKU) must follow a strict low-phenylalanine (Phe) diet in order to minimise the potentially disabling neuropsychological sequelae of the disorder. Research in this area has unsurprisingly focussed largely on managing blood Phe concentrations to protect the brain. Protein requirements in dietary management of PKU are met mostly from Phe-free protein substitutes with the intake of natural protein restricted to patient tolerance. Several reports have suggested that growth in early childhood in PKU is sub-optimal, relative to non-PKU control groups or reference populations. We reviewed the literature searching for evidence regarding PKU and growth as well as possible links between dietary management of PKU and growth. The search retrieved only limited evidence on the effect of PKU and its dietary management on growth. Physical development in PKU remains an under-studied aspect of this disorder., (Copyright © 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

The usual treatment for phenylketonuria (PKU) is a phenylalanine-restricted diet. Following this diet is challenging, and long-term adherence (and hence metabolic control) is commonly poor. Patients with PKU (usually, but not exclusively, with a relatively mild form of the disorder) who are responsive to treatment with pharmacological doses of tetrahydrobiopterin (BH4) have either lower concentrations of blood phenylalanine or improved dietary phenylalanine tolerance. The availability of a registered formulation of BH4 (sapropterin dihydrochloride, Kuvan®) has raised many practical issues and new questions in the dietary management of these patients. Initially, patients and carers must understand clearly the likely benefits (and limitations) of sapropterin therapy. A minority of patients who respond to sapropterin are able to discontinue the phenylalanine-restricted diet completely, while others are able to relax the diet to some extent. Care is required when altering the phenylalanine-restricted diet, as this may have unintended nutritional consequences and must be undertaken with caution. New clinical protocols are required for managing any dietary change while maintaining control of blood phenylalanine, ensuring adequate nutrition and preventing nutritional deficiencies, overweight or obesity. An accurate initial evaluation of pre-sapropterin phenylalanine tolerance is essential, and the desired outcome from treatment with sapropterin (e.g. reduction in blood phenylalanine or relaxation in diet) must also be understood by the patient and carers from the outset. Continuing education and support will be required thereafter, with further adjustment of diet and sapropterin dosage as a young patient grows.

Background: In children with phenylketonuria (PKU), it is possible that high carbohydrate protein substitutes may adversely affect blood phenylalanine control. We evaluated if a low carbohydrate, 'ready-to-drink' protein substitute would impact on short term blood phenylalanine control, weight and appetite in children with PKU aged 3-10 years., Methods: This was a 3-part, 5-week randomised, controlled, crossover study in which two different carbohydrate/protein-equivalent ratios in protein substitute [control protein substitute (CPS) median 1:1; trial protein substitute (TPS) 0.5:1] were compared. The effects on feeding behaviour, weight change and phenylalanine concentrations were studied. Fourteen children (12 boys; median age 6.3 y, range 3 to 9.7 y) with PKU on diet were recruited from 2 treatment centres., Results: Phenylalanine control did not deteriorate with TPS and remained unchanged between pre-study and CPS (p = 0.783). No statistical differences were noted in energy intake between the two study parts. Any changes in weight were similar between the two groups and there was limited change in feeding behaviour., Conclusion: This study suggests that the carbohydrate/protein-equivalent ratio of protein substitutes can be reduced to 0.5:1 with no loss of blood phenylalanine control or adverse effect on weight gain in children with PKU., (Copyright © 2011 Elsevier Inc. All rights reserved.)

In phenylketonuria (PKU), it is common for blood phenylalanine (Phe) concentrations to be outside optimal target ranges, particularly in teenagers and adults, indicating inadequate compliance. It is well known that significant noncompliance exists, and the situation in PKU would appear no different than other chronic conditions. In PKU, compliance is complex, being subject to diverse definitions, and factors influencing compliance include the nature and nurture of the patient, as well as the inconvenience, cost and availability of dietary treatment. It is also a dynamic process, with many patients changing between a state of compliance and partial and noncompliance. In PKU, compliance has received little rigorous study, and there have been few observational reports identifying barriers and behaviors impacting dietary compliance. Compliance assessment measures remain inadequately defined. The direct assessment of blood Phe concentration is perhaps the best overall measure, but there is no universal agreement about the number of Phe concentrations that should be within target range and frequency or timing of measurement. Although no one strategy for improving compliance is universally effective, and an individualized approach to noncompliance is essential, it is important to have clear evidence about the most effective strategies in achieving long-term dietary adherence in PKU.

Background: Dietary phenylalanine restriction is the cornerstone of phenylketonuria (PKU) management. However, there are no European consensus guidelines for its optimal dietary care., Methods: Detailed information on the routine dietary management of PKU was obtained from 10 European centres using structured questionnaires. Each centre was represented by one dietitian/nutritionist or physician (European Nutritionist Expert Panel)., Results: All centres screened for PKU within the first 10 days of life. PKU prevalence was highest in Turkey. The training, roles and responsibilities of dietitians and nutritionists varied widely; in some centres dietitians were responsible for managing the diet, while in others this was performed by a physician. There were marked differences in target blood phenylalanine concentrations, the dosages of protein substitutes, systems for allocating daily phenylalanine allowance, and the definition of foods that could be eaten without restriction ('free foods'). Eighty percent (n=8/10) of centres encouraged breastfeeding together with protein substitute in infants with PKU., Conclusions: Important differences exist among centres across Europe in the dietary management of PKU, and in support systems designed to assist patients in managing their diets. Further studies are needed to compare different dietary treatments with the aim of identifying best practice to optimise phenylalanine control and dietary adherence.