The Micronutrient Status of Patients with Phenylketonuria on Dietary Treatment: An Ongoing Challenge

Evans, Sharon; Daly, Anne; MacDonald, John K; Preece, Mary Anne; Santra, Saikat; Vijay, Suresh; Chakrapani, Anupam; MacDonald, Anita

doi:10.1159/000363391

Cited by 42 publications

(54 citation statements)

References 12 publications

(13 reference statements)

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“…This finding is comparable to outcomes in other studies [5,7,8]. However, the clinical relevance of the observed low zinc concentrations is unclear.…”

Section: Discussionsupporting

confidence: 89%

“…Low plasma selenium serum concentrations, as seen in 46% of our patients, have previously been reported in PKU [7,8]. Plasma selenium is an adequate biomarker for assessing the selenium status in patients on a special diet [30].…”

Section: Discussionmentioning

confidence: 58%

“…In some, the amount of added nutrients is calculated based on the needed daily calories, while in others advised intakes of protein/kilogram bodyweight is used to assess appropriate nutrient composition [5]. Studies evaluating intake and deficiencies of nutrients in PKU reported variable nutrient intakes and blood concentrations [6,7,8]. A minority of patients is responsive to a recently available (2009) treatment with tetrahydrobiopterin (BH4), a cofactor of PAH.…”

Section: Introductionmentioning

confidence: 99%

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Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria

et al. 2017

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Introduction: In phenylketonuria (PKU), a natural protein-restricted dietary treatment prevents severe cognitive impairment. Nutrient deficiencies may occur due to strict diet. This study is aimed at evaluating the dietary intake and blood concentrations of micronutrients and essential fatty acids (FA), bone mineral density (BMD) and fracture history in patients on long-term dietary treatment. Methods: Sixty early diagnosed Dutch patients (aged 1-39 years) were included in a multi-center cross-sectional study. Their dietary intake, blood concentrations of micronutrients, FA, fracture history and BMD were assessed. Results: Selenium dietary intake and serum concentrations were low in 14 and 46% of patients, respectively. The serum 25-OH vitamin D2 + D3 concentration was low in 14% of patients while 20% of patients had a low vitamin D intake. Zinc serum concentrations were below normal in 14% of patients, despite adequate intake. Folic acid serum concentrations and intake were elevated. Despite safe total protein and fat intake, arginine plasma concentrations and erythrocyte eicosapentaenoic acid were below reference values in 19 and 6% of patients, respectively. Low BMD (Z-score <-2) was slightly more prevalent in patients, but the lifetime fracture prevalence was comparable to the general population. Conclusions: Dutch patients with PKU on long-term dietary treatment have a near normal nutrient status. Supplementation of micronutrients of which deficiency may be deleterious (e.g., vitamin D and selenium) should be considered. BMD warrants further investigation.

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“…This finding is comparable to outcomes in other studies [5,7,8]. However, the clinical relevance of the observed low zinc concentrations is unclear.…”

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

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Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria

et al. 2017

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“…They frequently relax their protein-restricted diet and reduce AAM intake below prescribed amounts. Commonly, patients maintain their habitual dietary practices with a variable degree of natural protein restriction despite relaxed AAM intake, which constitutes a risk for nutritional imbalances and deficiencies [11,12]. In the present prospective cross-sectional study, eating habits, nutritional status, and selected nutritional biomarkers were evaluated in a cohort of adult PKU patients, in relation to their treatment compliance regarding AAM intake.…”

Section: Introductionmentioning

confidence: 99%

Effects of Inadequate Amino Acid Mixture Intake on Nutrient Supply of Adult Patients with Phenylketonuria

Hochuli¹,

Bollhalder²,

Thierer³

et al. 2017

Ann Nutr Metab

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Background: Adult phenylketonuria (PKU) patients often reduce their intake of amino acid mixture (AAM) to less than the prescribed amounts. Effects of reduced AAM intake on nutrient supply were evaluated. Methods: Nutrient intake was calculated in 20 adult PKU patients based on a structured food record and complemented by laboratory assessment of nutritional status. Patients were classified into 2 groups, (A) regular AAM intake, or (B) AAM intake below calculated requirements. Results: Group B consumed a higher proportion of natural protein (60 ± 23 vs. 33 ± 12%, p = 0.002); however, the total protein intake was below the recommended amounts in 60% of patients in group B versus 7% in group A (p = 0.03). Fat intake was higher in group B (39 ± 9% of energy vs. 31 ± 6%, p = 0.03), mainly from saturated fats. Selenium, folate, and vitamin B12 intake was below the recommended intake in group B. However, serum concentrations of these analytes remained within the normal range in both groups, although vitamin B12 levels were lower in group B. Plasma tyrosine correlated with AAM intake, and hydroxyproline correlated with the amount of natural protein consumed. Conclusion: Relaxed AAM intake resulted in insufficient nutrient supply, despite a compensatory increase in consumption of natural protein. Care needs to be taken to ensure adequate nutrition in adults with PKU.

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“…) that are difficult to consume in adequate amounts with dietary protein restriction (Lammardo et al 2013). Previous studies have shown that the PAH deficiency diet generally meets and even exceeds requirements for most nutrients (Evans et al 2014), but there are no reports of nutrient intake by source: food versus medical food. Phenylalanine restriction and medical food are recommended for life in all patients with PAH deficiency (Singh et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Impact of Dietary Intake on Bone Turnover in Patients with Phenylalanine Hydroxylase Deficiency

et al. 2017

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Phenylalanine hydroxylase (PAH) deficiency is a genetic disorder characterized by deficiency of the PAH enzyme. Patients follow a phenylalanine-restricted diet low in intact protein, and must consume synthetic medical food (MF) to supply phenylalanine-free protein. We assessed relationships between dietary intake and nutrient source (food or MF) on bone mineral density (BMD) and bone turnover markers (BTM) in PAH deficiency. Blood from 44 fasted females 11-52 years of age was analyzed for plasma phenylalanine, serum BTM [CTx (resorption), P1NP (formation)], vitamin D, and parathyroid hormone (PTH). BTM ratios were calculated to assess resorption relative to formation (CTx/P1NP). Dual energy X-ray absorptiometry measured total BMD and age-matched Zscores. Three-day food records were analyzed for total nutrient intake, nutrients by source (food, MF), and compliance with MF prescription. Spearman's partial coefficients (adjusted for age, BMI, energy intake, blood phenylalanine) assessed correlations. All had normal BMD for age (Z-score >À2). Sixty-four percent had high resorption and normal formation indicating uncoupled bone turnover. CTx/P1NP was positively associated with food phenylalanine (r 2 ¼ 0.39; p-value ¼ 0.017), energy (r 2 ¼ 0.41; p-value ¼ 0.011) and zinc (r 2 ¼ 0.41; pvalue ¼ 0.014). CTx/P1NP was negatively associated with MF fat (r 2 ¼ À0.44; p-value ¼ 0.008), MF compliance (r 2 ¼ À0.34; p-value ¼ 0.056), and positively with food sodium (r 2 ¼ 0.43; p-value ¼ 0.014). CTx/ P1NP decreased significantly with age (p-value ¼ 0.002) and higher PTH (p-value ¼ 0.0002). Phenylalanine was not correlated with any bone indicator. Females with PAH deficiency had normal BMD but elevated BTM, particularly resorption. More favorable ratios were associated with nutrients from MF and compliance. Younger females had less favorable BTM ratios. Promoting micronutrient intake through compliance with MF may impact bone metabolism in patients with PAH deficiency. Synopsis: Bone mineral density was normal in 44 females with PAH deficiency; however, bone turnover markers suggested uncoupling of bone resorption and formation, particularly in younger patients. Adequate nutrient intake from medical food and overall medical food compliance may positively impact bone turnover.

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The Micronutrient Status of Patients with Phenylketonuria on Dietary Treatment: An Ongoing Challenge

Cited by 42 publications

References 12 publications

Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria

Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria

Effects of Inadequate Amino Acid Mixture Intake on Nutrient Supply of Adult Patients with Phenylketonuria

Impact of Dietary Intake on Bone Turnover in Patients with Phenylalanine Hydroxylase Deficiency

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