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[Vitamin B 6 metabolism in phenylketonuria]
L A Kharitonchik1, V M Kodentsova, O A Vrzhesinskaia
1Institute of Nutrition at Russian Medical Academy, Moscow.
Insights
Vitamin B-6 metabolism differs in children with phenylketonuria (PKU), showing higher blood levels and altered excretion. Increased vitamin B-2 intake helps normalize vitamin B-6 status in these children.
Area of Science:
- Biochemistry
- Nutritional Science
- Pediatrics
Context:
- Phenylketonuria (PKU) is a genetic disorder affecting amino acid metabolism.
- Vitamin B-6 is crucial for various metabolic processes.
- Altered vitamin metabolism is suspected in PKU patients.
Purpose:
- To investigate vitamin B-6 metabolism in children with PKU.
- To compare vitamin B-6 status between PKU children and healthy individuals.
- To evaluate the effect of vitamin B-2 supplementation on vitamin B-6 status in PKU.
Summary:
- Urinary 4-pyridoxic acid excretion and plasma pyridoxal-5'-phosphate levels indicate different vitamin B-6 metabolism and saturation criteria in PKU children compared to healthy controls.
- PKU children exhibit elevated plasma pyridoxal-5'-phosphate levels, with 11 ng/ml proposed as the lower limit for adequate vitamin B-6 supply.
- Increased vitamin B-2 intake improved vitamin B-6 status markers in PKU children, bringing them closer to those of healthy children.
Impact:
- Highlights distinct vitamin B-6 requirements in PKU.
- Suggests a potential therapeutic role for vitamin B-2 in managing vitamin B-6 status in PKU.
- Underscores the need to re-evaluate optimal dietary recommendations for vitamins B-2 and B-6 in PKU patients.
Abstract:
Based on the analysis of the dependence of 4-pyridoxic acid urinary excretion from pyridoxal-5'-phosphate blood plasma level and its statistic distribution it has been shown that vitamin B-6 metabolism in children suffering from phenylketonuria and therefore the criteria of the body saturation with this vitamin differ from those for healthy people. Increased pyridoxal-5'-phosphate blood plasma level has been demonstrated for PKU children. The concentration of 11 ng/ml should be considered as a bottom border of the adequate supply with vitamin B-6. The elevated vitamin B-2 intake approximates vitamin B-6 status indexes of sick children to those usually measured in healthy children. The necessity for the reevaluation of vitamin B-2 and B-6 optimal diet content under this disease and its biochemical validation are discussed.