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Trace element status of children with PKU and normal children
S S Gropper1, P B Acosta, N Clarke-Sheehan
1Department of Nutrition and Food Science, Florida State University, Tallahassee.
Insights
Children with phenylketonuria (PKU) on elemental diets had higher trace mineral intake but similar blood levels to controls. This highlights potential risks for trace mineral deficiencies in PKU patients.
Area of Science:
- Biochemistry
- Pediatric Nutrition
- Metabolic Disorders
Background:
- Phenylketonuria (PKU) requires strict dietary management, often involving phenylalanine-free L-amino acid formulas.
- Trace minerals (chromium, copper, iron, selenium, zinc) are essential for various physiological functions.
- Elemental diets, while necessary for PKU, may impact nutrient absorption and status.
Purpose of the Study:
- To assess and compare the trace mineral status of children with PKU on specialized diets versus healthy children.
- To investigate potential discrepancies between trace mineral intake and serum concentrations in PKU patients.
- To identify risks associated with elemental diet formulations regarding trace mineral adequacy.
Main Methods:
- Cross-sectional study comparing 10 children with PKU and 9 healthy controls (ages 4-15.9 years).
- Collection of dietary records to determine trace mineral intake (chromium, copper, iron, selenium, zinc).
- Analysis of blood samples to measure serum concentrations of copper, iron, selenium, and zinc, and blood chromium.
Main Results:
- Children with PKU exhibited significantly higher mean intakes of copper, iron, and zinc compared to controls.
- Despite higher intake, serum concentrations of copper, iron, and zinc were not significantly different between groups.
- Normal children had higher mean serum selenium and blood chromium levels than children with PKU.
Conclusions:
- Elemental diets for PKU may lead to high intake but not necessarily improved serum levels of certain trace minerals.
- PKU patients on elemental diets are at risk for trace mineral deficiencies, particularly selenium and chromium.
- Manufacturers should review the composition and mineral ratios in medical foods to ensure optimal nutrient profiles.
Abstract:
The trace mineral (chromium, copper, iron, selenium, and zinc) status of 10 children (4 to 13.8 years) with phenylketonuria (PKU) and 9 normal children (6.5 to 15.9 years) was assessed. The children with PKU were treated with a phenylalanine-free L-amino acid mix that supplied the following percentages (mean +/- standard deviation) of total daily intake: energy, 45 +/- 13; protein, 75 +/- 11; copper (Cu), 62 +/- 10; iron (Fe), 82 +/- 7; selenium (Se), 40 +/- 20; and zinc (Zn) 87 +/- 8. Diet records and blood samples were collected from each subject. Children with PKU had significantly greater mean intakes of Cu, Fe, and Zn than normal children. Mean serum Cu, Fe, and Zn concentrations of the children with PKU and normal children were not different despite significantly greater intakes by the children with PKU. Normal children had a significantly greater mean serum Se concentration and a mean blood chromium concentration 1.6 times that of children with PKU. Individuals whose primary source of protein is an elemental diet are especially at risk for multiple trace mineral deficiencies. Manufacturers of chemically defined medical foods should evaluate composition, specifically molar ratios between minerals, as a basis for product formulation.