Positive effect of a simplified diet on blood phenylalanine control in different phenylketonuria variants, characterized by newborn BH4 loading test and PAH analysis

Zimmermann, Manuela R; Jacobs, Ph.; Fingerhut, Ralph; Torresani, Toni; Thöny, Beat; Blau, Nenad; Baumgartner, Matthias R.; Rohrbach, Marianne

doi:10.1016/j.ymgme.2012.04.016

Cited by 33 publications

(37 citation statements)

References 22 publications

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“…However, a special supplementation of vitamin C seems not to be necessary for PKU patients, as the most fruit and vegetables, the main sources for vitamin C, are low in protein and could be consumed in adequate amounts. Recent studies even showed that free consumption of fruits and vegetables does not impair the metabolic control in PKU patients (MacDonald et al 2003;Rohde et al 2012;Zimmermann et al 2012). Hence, independent from the therapeutic regimes (Phe restricted diet + AAM alone or in combination with BH 4 ) it should be the objective to encourage the patients to eat more fruits as well as vegetables, rather than supplementing vitamin C.…”

Section: Discussionmentioning

confidence: 99%

“…In the classical treatment of PKU it is necessary to plan meals exactly and to calculate the Phe content of all foods. Only recently, some specialized centres allow the unrestricted consumption of fruits and vegetables under certain conditions (Macdonald et al 2003;Rohde et al 2012;Zimmermann et al 2012). However, the individual Phe tolerance has to be respected.…”

Section: Introductionmentioning

confidence: 99%

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Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

et al. 2012

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Background: Since 2008 patients with BH 4 -sensitive phenylketonuria can be treated with sapropterin dihydrochloride (Kuvan®) in addition to the classic phenylalanine (Phe) restricted diet. The aim of this study was to evaluate the nutritional changes and micronutrient supply in patients with phenylketonuria (PKU) under therapy with tetrahydrobiopterin (BH 4 ).Subjects and Methods: 19 children with PKU (4-18 years) and potential BH 4 -sensitivity were included, 14 completed the study protocol. Dried blood Phe concentrations as well as detailed dietary records were obtained throughout the study at preassigned study days.Results: Eight patients could increase their Phe tolerance from 629 AE 476 mg to 2131 AE 1084 mg (P ¼ 0.006) under BH 4 while maintaining good metabolic control (Phe concentration in dried blood 283 AE 145 mM vs. 304 AE 136 mM, P ¼ 1.0), therefore proving to be BH 4 -sensitive. They decreased their consumption of special low protein products and fruit while increasing their consumption of high protein foods such as processed meat, milk and dairy products. Intake of vitamin D (P ¼ 0.016), iron (P ¼ 0.002), calcium (P ¼ 0.017), iodine (P ¼ 0.005) and zinc (P ¼ 0.046) significantly declined during BH 4 treatment while no differences in energy and macronutrient supply occurred.Conclusion: BH 4 -sensitive patients showed good metabolic control under markedly increased Phe consumption. However, the insufficient supply of some micronutrients needs consideration. Long-term multicenter settings with higher sample sizes are necessary to investigate the changes of nutrient intake under BH 4 therapy to further evaluate potential risks of malnutrition. Supplementation may become necessary.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

et al. 2012

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“…Other studies, although investigating small patient groups, could demonstrate the safety of dietary regimes without exact calculation of Phe from all ingested foods and beverages in children with classical PKU. These include investigations of small cohorts with respect to free use of fruits and vegetables in short-term [9], [11], as well as long-term settings [8], [10], [12]. The regimes 2, 3 and 4 revealed similar results, and in total represent a group of 80 patients.…”

Section: Discussionmentioning

confidence: 98%

“…Within this system, however, there are differences with respect to its degree of accuracy. So far, only few studies with small patient groups of children and adolescents were performed to examine the influence of dietary regimes on metabolic control [8], [9], [10], [11].…”

Section: Introductionmentioning

confidence: 99%

“…Dietary regime 3 combines free consumption of low protein foods (< 10 mg Phe/100 g), fruit and vegetables (< 75 mg Phe/100 g) with calculating the exact Phe content of all other foods [9], [10], [11], [12]. Dietary regime 4, the so-called “simplified diet”, consists of estimating the Phe content according to certain principles (free use of five portions of fruit and vegetables; free use of special low protein food including low protein bread, pasta and breakfast cereals; quantities of potatoes, rice and maize are discussed with the parents and then fixed for a period of time) [8]. Despite other instructions some patients only estimate their protein consumption and even consume varying amounts of protein rich foods e.g.…”

Section: Introductionmentioning

confidence: 99%

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Effect of dietary regime on metabolic control in phenylketonuria: Is exact calculation of phenylalanine intake really necessary?

Rohde

Thiele

Och

et al. 2015

Molecular Genetics and Metabolism Reports

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BackgroundA phenylalanine (Phe) restricted dietary management is required in phenylketonuria (PKU) to maintain good metabolic control. Nevertheless, five different models of dietary regimes, which differ in their accuracy of Phe documentation, are used. To investigate the effect of the dietary regime on metabolic control, a multicenter evaluation was performed.Patients/Methods149 patients (max. 800 mg Phe-intake/day; 108 children aged 1–9 years and 41 adolescents aged 10–15 years) could be included. They were separated according to age and dietary regime, revealed by a questionnaire on dietary habits. Dietary regimes vary from daily strict calculation of all Phe-intake (group 1) to a rather loose regime only estimating Phe-intake and including high protein food (group 5). Data were analyzed with respect to metabolic control (Phe-concentrations, Phe-concentrations above upper recommended limit during 6 months before the interview), Phe-intake (mg/day) and age (years).ResultsMedian Phe-concentrations in children did not differ significantly among diet groups (group 1: 161; 2: 229, 3: 236, 4: 249, 5: 288 μmol/l, p = 0.175). However, exact daily Phe calculation led to significantly lower percentage of Phe concentrations above the upper recommended limit (group 1: 17, 2: 50, 3: 42, 4: 50, 5: 75%, p = 0.035). All included patients showed good to acceptable metabolic control. Patients on the dietary regime with the least accuracy, consuming also high protein foods, showed the poorest metabolic control. Median Phe concentrations of all other groups remained within recommended ranges, including from groups not calculating special low protein foods, fruit and vegetables and using a simplified system of recording Phe-intake.In adolescents no significant differences among diet groups were revealed.ConclusionExact calculation of Phe content of all food is not necessary to achieve good metabolic control in children and adolescents with PKU. Excluding special low protein food, as well as fruit and vegetables from calculation of Phe-intake has no impact on metabolic control. However including protein rich food into the diet and simply estimating all Phe-intake appears insufficient. The simplification of dietary regime may be helpful in enhancing acceptability and feasibility.

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Simplified Diet for nutrition management of phenylketonuria: A survey of U.S. metabolic dietitians

et al. 2020

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Background Phenylketonuria (PKU) is an inherited metabolic disorder affecting the conversion of phenylalanine (Phe) to tyrosine. Medical nutrition therapy, consisting of a Phe‐restricted diet with medical formula, is the primary treatment for PKU. The Simplified Diet is an approach to PKU nutrition management that allows certain fruits, vegetables, and low‐protein foods to be eaten without measuring or tracking, referred to as free/uncounted foods. There is no consensus on how to implement this approach in metabolic centers in the United States (U.S.), and clinical practice varies. Aim This study describes the clinical experience of metabolic dietitians in U.S.‐based metabolic centers related to the use and implementation of the Simplified Diet. Methods A survey was developed and sent out to metabolic dietitians to query current clinical practices related to the Simplified Diet. Descriptive statistics were used to analyze responses. Results Sixty‐three dietitians managing ≥5 patients with PKU in U.S.‐based metabolic centers responded to the survey. Ninety‐eight percent of survey respondents reported using some version of the Simplified Diet in clinical practice. The survey identified areas of strong agreement, including introduction of the Simplified Diet at 6 to 12 months of age. The survey also identified areas of widespread variability, including specific Phe or protein thresholds for free/uncounted foods, and whether or not to set daily quantity limits on these foods. Conclusions Significant variability related to implementation of the Simplified Diet exists across U.S.‐based metabolic centers. This practice variability may contribute to differences in the patient experience across centers and may indicate a need for development of clinical guidelines.

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Positive effect of a simplified diet on blood phenylalanine control in different phenylketonuria variants, characterized by newborn BH4 loading test and PAH analysis

Cited by 33 publications

References 22 publications

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

Effect of dietary regime on metabolic control in phenylketonuria: Is exact calculation of phenylalanine intake really necessary?

Simplified Diet for nutrition management of phenylketonuria: A survey of U.S. metabolic dietitians

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