The effect of diet on total antioxidant status, ceruloplasmin, transferrin and ferritin serum levels in phenylketonuric children

A Comparison of the Treatment Effects of a Risperidone Solution, an Equal Ratio of DHA/ARA, and a Larger Ratio of Omega-6 PUFA Added to Omega-3 PUFA: An Open-Label Clinical Trial

We aimed to assess the efficacy, safety, and pharmacokinetics of an oral risperidone solution and two types of supplementations with PUFAs. We assigned 39 participants with mild ASD (mean age ± standard deviation = 14.6 ± 6.0 years) to three treatment groups (each n = 13): RIS-OS; equal doses of 240 mg of omega-3 PUFA docosahexaenoic acid and omega-6 PUFA arachidonic acid (1:1) (aravita); and omega-6 precursor linoleic acid (480 mg) and omega-3 precursor alpha-linolenic acid (120 mg) (4:1) (awake). The primary outcome was the Autism Diagnostic Interview-Revised score. The secondary outcomes were the Social Responsiveness Scale (SRS) and Aberrant Behavior Check scores. The results of the linear mixed-effects model revealed that the RIS-OS group exhibited significant improvement in the SRS subscale scores of social motivation at weeks 8, 12, and 16 compared with the aravita and awake groups, as well as in the SRS subscale score of social mannerisms at weeks 12 and 16 compared with the aravita group. Moreover, the RIS-OS group showed a trend towards significantly lower plasma ceruloplasmin (Cp) levels. Their plasma insulin-like growth factor (IGF) levels were significantly higher at week 8 than in the subsequent weeks. The high Cp and IGF levels may be attributed to reduced neuroinflammation. These findings demonstrate, firstly, that reduced inflammation through increased anti-inflammatory proteins such as Cp and IGF has clinical effects on the motivation-reward system and mannerisms in patients with ASD through the amelioration of dopamine D2, 5-HT2a, and 5-HT2b dysfunction.

Oxidative stress in phenylketonuria-evidence from human studies and animal models, and possible implications for redox signaling

Phenylketonuria (PKU) is one of the commonest inborn error of amino acid metabolism. Before mass neonatal screening was possible, and the success of introducing diet therapy right after birth, the typical clinical finds in patients ranged from intellectual disability, epilepsy, motor deficits to behavioral disturbances and other neurological and psychiatric symptoms. Since early diagnosis and treatment became widespread, usually only those patients who do not strictly follow the diet present psychiatric, less severe symptoms such as anxiety, depression, sleep pattern disturbance, and concentration and memory problems. Despite the success of low protein intake in preventing otherwise severe outcomes, PKU's underlying neuropathophysiology remains to be better elucidated. Oxidative stress has gained acceptance as a disturbance implicated in the pathogenesis of PKU. The conception of oxidative stress has evolved to comprehend how it could interfere and ultimately modulate metabolic pathways regulating cell function. We summarize the evidence of oxidative damage, as well as compromised antioxidant defenses, from patients, animal models of PKU, and in vitro experiments, discussing the possible clinical significance of these findings. There are many studies on oxidative stress and PKU, but only a few went further than showing macromolecular damage and disturbance of antioxidant defenses. In this review, we argue that these few studies may point that oxidative stress may also disturb redox signaling in PKU, an aspect few authors have explored so far. The reported effect of phenylalanine on the expression or activity of enzymes participating in metabolic pathways known to be responsive to redox signaling might be mediated through oxidative stress.

The phenylketonuria patient: A recent dietetic therapeutic approach

Phenylalanine hydroxylase (PAH) deficiency, commonly named phenylketonuria (PKU) is a disorder of phenylalanine (Phe) metabolism inherited with an autosomal recessive trait. It is characterized by high blood and cerebral Phe levels, resulting in intellectual disabilities, seizures, etc. Early diagnosis and treatment of the patients prevent major neuro-cognitive deficits. Treatment consists of a lifelong restriction of Phe intake, combined with the supplementation of special medical foods, such as Amino Acid medical food (AA-mf), enriched in tyrosine (Tyr) and other amino acids and nutrients to avoid nutritional deficits. Developmental and neurocognitive outcomes for patients, however, remain suboptimal, especially when adherence to the demanding diet is poor. Additions to treatment include new, more palatable foods, based on Glycomacropeptide that contains limited amounts of Phe, the administration of large neutral amino acids to prevent phenylalanine entry into the brain and tetrahydrobiopterin cofactor capable of increasing residual PAH activity. Moreover, further efforts are underway to develop an oral therapy containing phenylalanine ammonia-lyase. Nutritional support of PKU future mothers (maternal PKU) is also discussed. This review aims to summarize the current literature on new PKU treatment strategies.

Vitamin/mineral and micronutrient status in patients with classical phenylketonuria

BACKGROUND & AIMS

Strict low-phenylalanine diet is associated with an increased risk of developing micronutrient deficiencies in patients with phenylketonuria (PKU). The primary objective of this single-center, case-control study was to assess the nutritional parameters of patients with PKU on strict low-phenylalanine diet without vitamin and mineral supplementation compared to a healthy control group. Secondary objective was to identify the adequacy of vitamin/mineral supplementation in phenylalanine-free (Phe-free) amino acid formulas.

METHODS

A total of 112 age- and sex-matched patients with PKU and 36 controls who did not take vitamin or mineral supplementation at least for the last 6 months were enrolled in the study. Biochemical and hematological markers including hemoglobin, serum vitamin B12, folic acid, iron, ferritin, transferrin saturation, copper, prealbumin, albumin, total protein, phosphorus, calcium, 25-hydroxy vitamin D, zinc, vitamin A and vitamin E levels were screened from fasting morning blood samples.

RESULTS

One hundred and twelve patients with classical PKU (53 females, 47.3%) and 36 healthy controls (18 females, 50.0%) were enrolled in the study. The mean age of patients with PKU was 136.8 ± 82.1 months (18-377). Median serum vitamin B12 level of patients with PKU was found to be higher than the control group (p = 0.002). Vitamin B12 deficiency was 15.2% and 30.6% in patients with PKU and healthy controls, respectively (p = 0.040). Mean serum folic acid level was higher in patients with PKU than the control group (p < 0.0001). In 55.4% of patients with PKU, and 2.8% of the control group, serum folic acid level was above the reference range (p < 0.0001). The frequency of ferritin and prealbumin values above the reference range was found to be higher in patients with PKU compared to the control group (44.4% vs 16.9%, p = 0.001; 38.8% vs 22.1%, p = 0.020, respectively). 25-Hydroxy vitamin D deficiency was detected in 53.6% and 47.2% of patients with PKU and the control group, respectively. Mean serum copper level was higher in the well-controlled (114.3 ± 26.7 μg/dL) group than the poorly controlled group (101.0 ± 29.1 μg/dL) (p = 0.022).

CONCLUSIONS

Phe-free amino acid formulas provide adequate vitamin A and zinc levels in patients with PKU, and result in excess folic acid, vitamin B12, copper and vitamin E values that are higher than required levels. Our results demonstrate a high percentage of vitamin D deficiency in patients with classical PKU and also in healthy controls in Turkey.

Serum ferritin level as an early indicator of metabolic dysregulation in young obese adults - a cross-sectional study

The aim of this study was to investigate the relationship between serum ferritin level and antioxidative status and metabolic dysregulation in young adult obese population. This cross-sectional study included 300 subjects of either sex, grouped as obese and non-obese subjects. The body mass index, total iron binding capacity, fasting blood glucose, superoxide dismutase activity, and levels of serum ferritin, iron, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, glutathione, and vitamin C were estimated. Analysis showed a significant alteration in all the parameters in obese adults. The correlation of ferritin level and body mass index showed a positive correlation (r = -0.81, p < 0.001, respectively) with levels of fasting blood glucose, superoxide dismutase, total cholesterol, low-density lipoprotein cholesterol, and triglyceride in obese individuals, whereas an insignificant correlation with vitamin C and glutathione level was observed in obese individuals. The significant positive correlation of ferritin level with the metabolic parameters and some antioxidative parameters in obese individuals signifies the development of metabolic disorders. Therefore, estimation of serum ferritin level will be an important early indicator for the risk of developing metabolic disorders in young adults.

Status of nutrients important in brain function in phenylketonuria: a systematic review and meta-analysis

Background

Despite early and ongoing dietary management with a phe-restricted diet, suboptimal neuropsychological function has been observed in PKU. The restrictive nature of the PKU diet may expose patients to sub-optimal nutritional intake and deficiencies which may impact normal brain function. A systematic review of the published literature was carried out, where possible with meta-analysis, to compare the status of nutrients (Nutrients: DHA, EPA phospholipids, selenium, vitamins B₆, B₁₂, E, C, A, D, folic acid, choline, uridine, calcium, magnesium, zinc, iron, iodine and cholesterol) known to be important for brain development and functioning between individuals with PKU and healthy controls.

Results

Of 1534 publications identified, 65 studies met the entry criteria. Significantly lower levels of DHA, EPA and cholesterol were found for PKU patients compared to healthy controls. No significant differences in zinc, vitamins B₁₂, E and D, calcium, iron and magnesium were found between PKU patients and controls. Because of considerable heterogeneity, the meta-analyses findings for folate and selenium were not reported. Due to an insufficient number of publications (< 4) no meta-analysis was undertaken for vitamins A, C and B₆, choline, uridine, iodine and phospholipids.

Conclusions

The current data show that PKU patients have lower availability of DHA, EPA and cholesterol. Compliance with the phe-restricted diet including the micronutrient fortified protein substitute (PS) is essential to ensure adequate micronutrient status. Given the complexity of the diet, patients’ micronutrient and fatty acid status should be continuously monitored, with a particular focus on patients who are non-compliant or poorly compliant with their PS. Given their key role in brain function, assessment of the status of nutrients where limited data was found (e.g. choline, iodine) should be undertaken. Standardised reporting of studies in PKU would strengthen the output of meta-analysis and so better inform best practice for this rare condition.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0839-x) contains supplementary material, which is available to authorized users.

Endogenous non-enzymatic antioxidants in the human body

The exposure of cells, tissues and extracellular matrix to harmful reactive species causes a cascade of reactions and induces activation of multiple internal defence mechanisms (enzymatic or non-enzymatic) that provide removal of reactive species and their derivatives. The non-enzymatic antioxidants are represented by molecules characterized by the ability to rapidly inactivate radicals and oxidants. This paper focuses on the major intrinsic non-enzymatic antioxidants, including metal binding proteins (MBPs), glutathione (GSH), uric acid (UA), melatonin (MEL), bilirubin (BIL) and polyamines (PAs).

Vitamin and mineral status in patients with hyperphenylalaninemia

Natural sources of protein and some vitamins and minerals are limited in phenylketonuria (PKU) treated patients, who should receive optimal supplementation although this is not yet fully established. We conducted a cross-sectional observational multicenter study including 156 patients with hyperphenylalaninemia. Patients were stratified by age, phenotype, disease detection and type of treatment. Annual median blood phenylalanine (Phe) levels, Phe tolerance, anthropometric measurements, and biochemical parameters (total protein, prealbumin, electrolytes, selenium, zinc, B12, folic acid, ferritin, 25-OH vitamin D) were collected in all patients. 81.4% of patients had biochemical markers out of recommended range but no clinical symptoms. Total protein, calcium, phosphorus, B12, ferritin, and zinc levels were normal in most patients. Prealbumin was reduced in 34.6% of patients (74% with PKU phenotype and 94% below 18 years old), showing almost all (96.3%) an adequate adherence to diet. Selenium was diminished in 25% of patients (95% with PKU phenotype) and also 25-OHD in 14%. Surprisingly, folic acid levels were increased in 39% of patients, 66% with classic PKU. Phosphorus and B12 levels were found diminished in patients with low adherence to diet. Patients under BH4 therapy only showed significant lower levels of B12. This study shows a high percentage of prealbumin and selenium deficiencies as well as an increased level of folic acid in PKU treated patients, which should lead us to assess an adjustment for standards supplements formulated milks.

Antioxidant treatment strategies for hyperphenylalaninemia

Hyperphenylalaninemia (HPA) leads to increased oxidative stress in patients with phenylketonuria (PKU) and in animal models of PKU. Early diagnosis and immediate adherence to a phenylalanine-restricted diet prevents HPA and, consequently, severe brain damage. However, treated adolescent and adult PKU patients have difficulties complying with the diet, leading to an oscillation of phenylalanine levels and associated oxidative stress. The brain is especially susceptible to reactive species, and oxidative stress might add to the impaired cognitive function found in these patients. The restricted PKU diet has a very limited nutrient content from natural foods and almost no animal protein, which reduces the intake of important compounds. These specific compounds can act as scavengers of reactive species and can be co-factors of antioxidant enzymes. Supplementation with nutrients, vitamins, and tetrahydropterin has given quite promising results in patients and animal models. Antioxidant supplementation has been studied in HPA, however there is no consensus about its always beneficial effects. In this way, regular exercise could be a beneficial addition on antioxidant status in PKU patients. A deeper understanding of PKU molecular biochemistry, and genetics, as well as the need for improved targeted treatment options, could lead to the development of new therapeutic strategies.

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.

Serum Ferritin Is Differentially Associated with Anti-oxidative Status and Insulin Resistance in Healthy Obese and Non-obese Women

BACKGROUND

Ferritin is known to be associated with insulin resistance (IR) and oxidative stress; however, recent studies have shown that there is an association between ferritin and anti-oxidative status. To date, the biphasic response of ferritin to oxidative stress has not been fully evaluated. Thus, we investigated the association between ferritin and IR and anti-oxidative status in obese and non-obese women.

METHODS

We evaluated the homeostasis model assessment of insulin resistance (HOMA-IR) and total anti-oxidant status (TAS) in a total of 111 healthy women between the ages of 32 and 68 years.

RESULTS

In all of the study subjects, ferritin levels were positively correlated with age (r = 0.38, P < 0.001), body mass index (r = 0.24, P = 0.01), TAS (r = 0.38, P < 0.001) and HOMA-IR (r = 0.20, P = 0.04). In the subgroup analysis, ferritin levels were correlated with age (r = 0.39, P < 0.001) and TAS (r = 0.43, P < 0.001) in the non-obese group and with insulin (r = 0.50, P = 0.02) and HOMA-IR (r = 0.52, P = 0.01) levels in the obese group. On stepwise multiple linear regression analysis, ferritin was found to be independently associated with TAS (B = 177.16, P < 0.0001) in the non-obese group and independently associated with HOMA-IR (B = 30.36, P = 0.01) in the obese group.

CONCLUSION

Our findings suggest ferritin is associated with IR in obese women and with anti-oxidative status in non-obese women. Further studies are warranted to elucidate the precise role of ferritin in obesity.

Oxidative stress in phenylketonuria: future directions

Phenylketonuria represents the most prevalent inborn error of amino acid metabolism. In early diagnosed patients adequate and continued dietary treatment results in a good neurologic outcome. Natural protein and phenylalanine-restricted diet, even if rich in fruits and vegetables, represents a serious risk for nutritional deficiencies, albeit universally accepted. In the last few years, a growing number of reports have been describing oxidative stress as a concern in phenylketonuric patients. The diet itself includes good sources of dietary antioxidants (phytochemicals, some vitamins and minerals) but also a risk factor for some deficiencies (selenium, zinc, ubiquinone-10 and L-carnitine). Additionally, the extreme stringency of the diet may impose a reduced synthesis of endogenous antioxidants (like ubiquinone-10 and glutathione). Furthermore, increased phenylalanine levels, and its metabolites, may enhance the endogenous synthesis of reactive species and free radicals and/or interfere with the endogenous synthesis of enzymatic antioxidants (like glutathione peroxidase). Therefore, oxidative stress will probably increase, mainly in late diagnosed patients or in those with bad metabolic control. Considering the known association between oxidative stress, obesity and cardiovascular disease, it seems advisable to look further to the impact of oxidative stress on body macromolecules and structures (like lipoprotein oxidation), especially in phenylketonuric patients with late diagnosis or bad metabolic control, in order to prevent future increased risks. Recommendations for PKU patient's clinical follow-up improvement and educational goals are included.

Oxidative stress in phenylketonuric patients

Phenylketonuria is the most frequent disturbance of amino acid metabolism. Untreated patients present mental retardation whose pathophysiology is not completely established. In this work we discuss the oxidative stress in phenylketonuric patients. Several studies have shown reduction in antioxidant defenses, possibly due to dietary restriction of nutrients with antioxidant properties and increase in oxidative damage to biomolecules, probably secondary to increased formation of reactive species. Therefore, antioxidants could be considered an adjuvant therapy in phenylketonuria.