Laurie Bernstein

Nutrient intakes and physical growth of children with phenylketonuria undergoing nutrition therapy

OBJECTIVE To evaluate nutrient intakes, plasma phenylalanine (PHE) and tyrosine (TYR) concentrations, and physical growth of children with phenylketonuria undergoing nutrition management. DESIGN Children were fed three different medical foods during a one-year study. Subjects/setting Children were evaluated at baseline and every three months in metabolic clinics. Childrens diets were managed at home. Statistical analyses Intakes of medical foods and nutrients, number of diaries with nutrients <67% and <100% of Recommended Dietary Intakes (RDI), and mean plasma PHE and TYR concentrations were compared among groups using two-way ANOVA. chi-squared test compared the percentage of plasma PHE and TYR concentrations in each group in specific categories. Height and body mass index were plotted against National Center for Health Statistics reference data; means were compared among groups. Tukeys test compared groups with significant treatment effects. RESULTS Mean intakes of nutrients, except energy by all groups and vitamin B-12 by the Periflex-fed group, met or exceeded RDIs. The oldest children tended to have the highest PHE intakes and plasma PHE concentrations. Mean length or height z score indicated normal linear growth. Mean body mass index z scores at study end suggested many children were overweight. APPLICATIONS Dietitians should prescribe adequate medical food and encourage children with phenylketonuria to ingest all prescribed daily. Linear growth of children, where mean protein equivalent intakes ranged from 113% to 129% of RDI, was normal, demonstrating the need for a protein intake greater than RDIs when an elemental diet is the primary protein source. Dietitians should prescribe and carefully monitor energy intake, physical activity, and weight.

Nutrient Intake and Growth of Infants with Phenylketonuria Undergoing Therapy

BACKGROUND Because of reports of poor growth, a study was conducted for 6 months in 35 infants with classic phenylketonuria diagnosed during the neonatal period who were fed Phenex-1 Amino Acid Modified Medical Food With Iron (Ross Products Division, Columbus, OH, U.S.A.).as their primary protein source. METHODS Diet diaries and anthropometric measures were obtained monthly as part of a larger study in which nutrition status was evaluated. RESULTS In 6-month-old infants, mean percentiles for crown-heel length (59.14+/-4.31 SEM), head circumference (63.88+/-4.50) and weight (71.51+/-4.25) were normal. Mean (+/- SEM) daily intake of medical food was 79+/-4 g; protein and energy intakes were 17.3+/-0.6 g and 2772+/-75.6 kJ (660+/-18 kcal). Mean daily phenylalanine and tyrosine intakes per kilogram of body weight were 40+/-1 mg and 219+/-9 mg. Intakes of protein, energy, and tyrosine were positively correlated with crown-heel length, head circumference, and weight at 3 months of study. Overall plasma phenylalanine and tyrosine concentrations during the 6-month study were 297+/-41 micromol/l and 58+/-5 micromol/l, respectively. Neither plasma phenylalanine nor tyrosine concentration was correlated with growth. CONCLUSION Phenex-1 supports normal growth when fed in adequate amounts. These data support those of the Medical Research Council Working Party on Phenylketonuria for 3 g/kg per day of amino acids from medical food.

A re-evaluation of life-long severe galactose restriction for the nutrition management of classic galactosemia

The galactose-restricted diet is life-saving for infants with classic galactosemia. However, the benefit and extent of dietary galactose restriction required after infancy remain unclear and variation exists in practice. There is a need for evidence-based recommendations to better standardize treatment for this disorder. This paper reviews the association between diet treatment and outcomes in classic galactosemia and evaluates the contribution of food sources of free galactose in the diet. Recommendations include allowing all fruits, vegetables, legumes, soy products that are not fermented, various aged cheeses and foods containing caseinates. Further research directions are discussed.

Intake and blood levels of fatty acids in treated patients with phenylketonuria.

Background Investigators in Italy and Spain have suggested that therapy for patients with phenylketonuria (PKU) may result in essential fatty acid (EFA) deficiency. Objectives of this study were to determine if the diets of patients with PKU in the United States provided adequate EFA intakes and whether patients could form long-chain polyunsaturated fatty acids. Methods Patients (1–13 years of age) with classic PKU undergoing therapy and their non-PKU sibling closest in age were compared. Nutrient intakes were calculated from 3-day diet diaries. Fatty acids in plasma and erythrocytes were identified and quantified. Paired t tests compared results for the patients and their non-PKU siblings. Results Twenty-eight patients and 26 siblings were studied. Mean fat intake was greatest by siblings (34.8 ± 1.3% of energy) and lowest by Phenyl-Free–fed patients (19.5 ± 1.2% of energy;P < 0.05). Fat intake (30.4 ± 1.8% of energy) by Phenex-fed patients did not differ from that of siblings. Percentage of energy ingested as C18:2n-6 and C18:3n-3 did not differ significantly between patients and siblings. No clinically significant, consistent differences were found in fatty acid levels (wt%) in plasma or erythrocytes between patients with PKU and siblings. Conclusions No patient in this study exhibited a Holman index of EFA deficiency. Siblings ingested animal protein containing C20:5n-3 and C22:6n-3 fatty acids, and this may account for their greater wt% of these plasma and erythrocyte fatty acids. Because patients with PKU do not ingest fatty acids >C18 but C20:4n-6, C20:5n-3, and C22:6n-3 were found in their plasma and erythrocytes, in vivo synthesis from C18:2n-6 and C18:3n-3 appears to occur. Lack of EFA deficiency in patients in this study may be the result of the use of canola and soy oils containing C18:2n-6 and C18:3n-3 rather than olive oil in the diets.

Galactose Content of Legumes, Caseinates, and Some Hard Cheeses: Implications for Diet Treatment of Classic Galactosemia

There are inconsistent reports on the lactose and/or galactose content of some foods traditionally restricted from the diet for classic galactosemia. Therefore, samples of cheeses, caseinates, and canned black, pinto, kidney, and garbanzo beans were analyzed for free galactose content using HPLC with refractive index or pulsed amperometric detection. Galactose concentrations in several hard and aged cheeses and three mild/medium Cheddars, produced by smaller local dairies, was <10 mg/100 g sample compared to 55.4 mg/100 g sample in four sharp Cheddars produced by a multinational producer. Galactose in sodium and calcium caseinate ranged from undetectable to 95.5 mg/100 g sample. Free galactose level in garbanzo beans was lower than previously reported at 24.6 mg/100 g sample; black beans contained 5.3 mg/100 g, and free galactose was not detected in red kidney or pinto beans. These data provide a basis for recommending inclusion of legumes, caseinate-containing foods, and some aged hard cheeses that had been previously restricted in the diet for individuals with galactosemia.

Network phenylketonuria conference: an effective tool for facilitating adherence to diet therapy in individuals with phenylketonuria.

A 2-day conference, titled “Network PKU,” was developed for adolescents and adults with phenylketonuria and their family members. It was designed to facilitate diet adherence in the current patient population. A novel venue–a local culinary academy–and a variety of learning formats were employed. Results of surveys, conducted at the end of the conference and at 4 months postconference, indicate that it was perceived by attendees to be a valuable and effective tool for facilitating diet maintenance in the assessed time period. Potential factors leading to the success of the conference format are also discussed.

Amino Acids and Inherited Amino Acid-Related Disorders

Amino acids perform multiple essential physiological roles in humans, and accordingly, their importance to health has been the subject of extensive attention. In this special issue of the Journal of Nutrition and Metabolism, we focus on the various inborn errors of amino acid metabolism, their diagnostic challenges, new treatment approaches, and recent advances in patient monitoring as well as clinical outcomes.

Multiclinic Observations on the Simplified Diet in PKU

Phenylketonuria is an inborn error of metabolism that historically has been treated with a strict phenylalanine-restricted diet where all foods are weighed and measured. This is cumbersome and difficult for patients and caregivers, especially patients with high phenylalanine blood concentrations who often have neurocognitive deficits. The Simplified Diet is an alternative approach that allows for increased flexibility, promotes healthy food choices, and is easier to manage than a traditional diet for PKU. This paper describes the implementation of the Simplified Diet and outlines education, counseling strategies, and challenges encountered by three metabolic clinics in the United States.

Nutrition Management of Glutaric Acidemia Type 1

Glutaric acidemia type 1 (GA-1) is an autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism. A defect of glutaryl-CoA dehydrogenase results in the accumulation of 3-hydroxyglutaric acid and glutaric acid. Nutrition management of GA-1 consists of restricting lysine and tryptophan, supplementing L-carnitine, and providing sufficient energy to prevent catabolism. Patients with GA-1 have a particularly high risk of permanent cerebral damage from a metabolic crisis.

The Diet for Galactosemia

Classical galactosemia can result in life-threatening complications including failure to thrive, hepatocellular damage, and E. coli sepsis in untreated infants. Initiation of a soy formula or a lactose-free medical food within the first few days of life can mitigate these complications. Patients with classical galactosemia are at increased risk for developmental delay, speech problems, and neurological complications, even with lifelong dietary treatment. Dairy products are the primary source of dietary galactose. Galactose is produced endogenously and accounts for a greater contribution to the total galactose pool than the small amounts of galactose found in plant-based foods.