The need of essential amino acids in children. An evaluation based on the intake of phenylalanine, tyrosine, leucine, isoleucine, and valine in children with phenylketonuria, tyrosine amino transferase defect, and maple syrup urine disease

The diet of children with blocks in the metabolism of five amino acids has been investigated to evaluate the need for these amino acids in the maintenance of normal growth and development. Two children with phenylketonuria, one child with tyrosine aminotransferase defect and one child with maple syrup urine disease are included in the study. The growth and development of the children have been within the normal range except for language development, which was retarded in the maple syrup urine disease child. The need for phenylalanine, phenylalanine and tyrosine combined and isoleucine, leucine, and valine for protein synthesis in growing children was investigated by registering the intake of phenylalanine in the phenylketonuria children, the intake of phenylalanine and tyrosine in the tyrosine amino transferase defect child and isoleucine, leucine and valine in the maple syrup urine disease child. The significance of this intake, defined as the sufficient intake, is discussed, as well as the difference between the sufficient intake and requirement. The sufficient intake is compared with former studies on requirement. There is good agreement between the sufficient intake and requirement of phenylalanine and tyrosine. The sufficient intake of isoleucine, leucine, and valine as judged from our study is lower than in former studies on requirement.