Nutritional status of patients with phenylketonuria in Japan.
Accumulating evidence suggests that hyperphenylalaninemia in phenylketonuria (PKU) can cause neuropsychological and psychosocial problems in diet-off adult patients, and that such symptoms improve after resumption of phenylalanine-restricted diet, indicating the need for lifetime low-phenylalanine diet. While limiting protein intake, dietary therapy should provide adequate daily intake of energy, carbohydrates, fat, vitamins, and microelements. We evaluated nutrient balance in 14 patients with classical PKU aged 4-38 years. Approximately 80-85% of the recommended dietary allowance (RDA) of protein in Japanese was supplied through phenylalanine-free (Phe-free) milk and Phe-free amino acid substitutes. Nutritional evaluation showed that the calorie and protein intakes were equivalent to the RDA. Phenylalanine intake was 9.8 ± 2.2 mg/kg of body weight/day, which maintained normal blood phenylalanine concentration by the 80% Phe-free protein rule. The protein, fat, and carbohydrate ratio was 9.5:23.9:66.6% with relative carbohydrate excess. Phe-free milk and amino acid substitutes provided 33.7% of carbohydrate, 82.1% of protein, and 66.7% of fat intake in all. Selenium and biotin intakes were 25.0% and 18.1% of the RDA and adequate intake (AI) for Japanese, respectively; both were not included in Phe-free milk. PKU patients showed low serum selenium, low urinary biotin, and high urinary 3-hydroxyisovaleric acid in this study. The intakes of magnesium, zinc, and iodine were low (71.5%, 79.5%, and 71.0% of the RDA, respectively) and that of phosphorus was 79.7% of the AI, although they were supplemented in Phe-free milk. PKU patients depend on Phe-free milk and substitutes for daily requirement of microelements and vitamins as well as protein and fat. Development of low-protein food makes it possible to achieve the aimed phenylalanine blood level, but this lowers the intake of microelements and vitamins from natural foods. The dietary habits vary continuously with age and environment in PKU patients. We recommend the addition of selenium and biotin to Phe-free milk in Japan and the need to review the composition of microelements and vitamins in A-1 and MP-11 preparations.
Department of Genetics, Hyogo College of Medicine, Nishinomiya 663-8501, Japan; Okano Children's Clinic, Izumi 594-0071, Japan.
Yoshiyuki
Y
Okano
Nutrition Dietary Section, Osaka City University Hospital, Osaka 545-0051, Japan.
Toshikazu
T
Hattori
Nutrition Dietary Section, Osaka City University Hospital, Osaka 545-0051, Japan.
Hiroki
H
Fujimoto
Nutrition Dietary Section, Osaka City University Hospital, Osaka 545-0051, Japan.
Kaori
K
Noi
Okano Children's Clinic, Izumi 594-0071, Japan.
Miki
M
Okamoto
Department of Health and Nutrition, Faculty of Human Science, Osaka Aoyama University, Mino 562-8580, Japan; Department of Dietary Environment Analysis, School of Human Science and Environment, University of Hyogo, Himeji 670-0092, Japan.
Toshiaki
T
Watanabe
Department of Health and Nutrition, Faculty of Human Science, Osaka Aoyama University, Mino 562-8580, Japan.
Ryoko
R
Watanabe
The Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino 583-8555, Japan.
Rika
R
Fujii
Department of Clinical Genetics, Hyogo College of Medicine, Nishinomiya 663-8501, Japan.
Tomoko
T
Tamaoki
Biotin; Iodine; Magnesium; Microelement; Nutrition; Phenylalanine hydroxylase; Phenylketonuria; Phosphorus; Selenium; Vitamin; Zinc