Ernährung bei angeborenen Stoffwechselerkrankungen — ein Spagat zwischen Genuss und Therapie

For many inborn metabolic diseases, a lifelong diet is a crucial part of the therapy since pharmacological therapy is available for only a few conditions and patients. The implementation of a low natural protein diet with a reduced intake of natural protein and the complementary use of synthetic amino acid mixtures is described using the examples of phenylketonuria and urea cycle disorders focusing on children and adolescents. For phenylketonuria, the amino acid supplement is free of phenylalanine whereas for urea cycle disorders, it exclusively consists of essential amino acids. The dietary treatment aims to maintain metabolic stability and to prevent accumulation of toxic metabolites. At the same time, the nutritional requirements to ensure growth and development must be met. Therefore, patients need to follow strict rules regarding the choice of food products. This restrictive therapy interferes with the desire for autonomy and the joy of eating and often results in a reduced quality of life.Following the diet is crucial for a favorable outcome. To meet its requirements, patients and their families are provided with training. It is a~great challenge not only to support the patients and their families in all practical aspects of dietary management, but also to motivate them to lifelong adherence in order to ensure the best possible outcome.Bei vielen angeborenen Stoffwechselkrankheiten ist eine lebensbegleitende Diät von Geburt an fester Bestandteil der Therapie. Alternative medikamentöse Therapieansätze stehen erst für einige wenige Patienten zur Verfügung. Am Beispiel der Phenylketonurie und der Harnstoffzyklusstörungen wird das Prinzip der eiweißdefinierten Diät mit dem Schwerpunkt auf Kinder und Jugendliche erläutert. Die Herausforderungen, die sich bei dieser Ernährungstherapie ergeben, werden aufgezeigt. Bei der eiweißdefinierten Diät erfolgt eine verminderte Zufuhr von natürlichem Protein, ergänzt durch die Gabe spezieller Aminosäuremischungen. Diese enthalten bei der Phenylketonurie kein Phenylalanin, bei den Harnstoffzyklusdefekten ausschließlich essenzielle Aminosäuren. Mithilfe der Diät soll zum einen eine gute metabolische Einstellung erreicht und die Anhäufung toxischer Metabolite vermieden werden. Zum anderen muss eine bedarfsdeckende Energie- und Nährstoffversorgung für das adäquate Wachstum und die Entwicklung des Kindes gewährleistet sein. Für die Patienten bedeutet dies, sich an restriktive Vorgaben bei der Lebensmittelauswahl halten zu müssen. Diese konkurrieren oft mit dem Bedürfnis nach Freiheit/Spontaneität und dem Genuss bei der Nahrungsaufnahme. Viele Patienten empfinden ihre Diät daher als drastische Einschränkung der Lebensqualität. Eine konsequente Umsetzung der Diät ist entscheidend für die Prognose der Erkrankungen. Hierfür bringen die Patienten und ihre Familien oft unterschiedliche Voraussetzung und Fähigkeiten mit. Für Therapeuten stellt es eine große Herausforderung dar, die Patienten nicht nur bei der praktischen Umsetzung ihrer Diät in allen Lebensabschnitten zu unterstützen, sondern auch zu einer langfristigen Adhärenz zu motivieren, um ein bestmögliches Outcome zu erreichen

Long-Term Growth in Phenylketonuria: A Systematic Review and Meta-Analysis

There is an ongoing debate regarding the impact of phenylketonuria (PKU) and its treatment on growth. To date, evidence from studies is inconsistent, and data on the whole developmental period is limited. The primary aim of this systematic review was to investigate the effects of a phenylalanine (Phe)-restricted diet on long-term growth in patients with PKU. Four electronic databases were searched for articles published until September 2018. A total of 887 results were found, but only 13 articles met eligibility criteria. Only three studies had an adequate methodology for meta-analysis. Although the results indicate normal growth at birth and during infancy, children with PKU were significantly shorter and had lower weight for age than reference populations during the first four years of life. Impaired linear growth was observed until the end of adolescence in PKU. In contrast, growth impairment was not reported in patients with mild hyperphenylalaninemia, not requiring dietary restriction. Current evidence indicates that even with advances in dietary treatments, "optimal" growth outcomes are not attained in PKU. The majority of studies include children born before 1990s, so further research is needed to show the effects of recent dietary practices on growth in PKU.info:eu-repo/semantics/publishedVersio

Optimising growth in phenylketonuria:Current state of the clinical evidence base

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 understudied aspect of this disorder. (C) 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved

Dietary management practices in phenylketonuria across European centres

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. (C) 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved

Main issues in micronutrient supplementation in phenylketonuria

For almost all patients with PKU, a low phenylalanine diet is the basis of the treatment despite a widely varying natural protein tolerance. A vitamin and mineral supplement is essential and it is commonly added to a phenylalanine-free (phe-free) source of l-amino acids. In PKU, many phe-free l-amino acid supplements have age-specific vitamin and mineral profiles to meet individual requirements. The main micronutrient sources are chemically derived and their delivery dosage is usually advised in three or more doses throughout the day. Within the EU, the composition of VM (vitamin and mineral) phe-free l-amino acid supplements is governed by the Foods for Special Medical Purposes (FSMP) directive (European Commission Directive number 1999/21/EC and amended by Directive 2006/141/EC). However the micronutrient composition of the majority fails to remain within FSMP micronutrient maximum limits per 100. kcal due to their low energy content and so compositional exceptions to the FSMP directive have to be granted for each supplement. All patients with PKU require an annual nutritional follow-up, until it has been proven that they are not at risk of any vitamin and mineral imbalances. When non-dietary treatments are used to either replace or act as an adjunct to diet therapy, the quality of micronutrient intake should still be considered important and monitored systematically. European guidelines are required about which micronutrients should be measured and the conditions (fasting status) for monitoring. © 2013 Elsevier Inc.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Micronutrient status in phenylketonuria

Patients with phenylketonuria (PKU) encompass an 'at risk' group for micronutrient imbalances. Optimal nutrient status is challenging particularly when a substantial proportion of nutrient intake is from non-natural sources. In PKU patients following dietary treatment, supplementation with micronutrients is a necessity and vitamins and minerals should either be added to supplement phenylalanine-free l-amino acids or given separately. In this literature review of papers published since 1990, the prevalence of vitamin and mineral deficiency is described, with reference to age of treatment commencement, type of treatment, dietary compliance, and dietary practices. Biological micronutrient inadequacies have been mainly reported for zinc, selenium, iron, vitamin B12 and folate. The aetiology of these results and possible clinical and biological implications are discussed. In PKU there is not a simple relationship between the dietary intake and nutritional status, and there are many independent and interrelated complex factors that should be considered other than quantitative nutritional intake. © 2013 Elsevier Inc.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Weight Management In Phenylketonuria: What Should Be Monitored?

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. (C) 2015 S. Karger AG, BaselWoSScopu

Adjusting Diet With Sapropterin In Phenylketonuria: What Factors Should Be Considered?

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 (R)) 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.WoSScopu