Fasting plasma amino acid concentrations in PKU children on two different levels of protein intake

Two groups of children with phenylketonuria were treated with different amounts of protein. One group (RDA group) received protein as recommended by the U.S. Food and Nutrition Board, the other (FAO group) the amount recommended by the FAO/WHO 1973 ad hoc Expert Committee. Two of the children in the FAO group showed a decrease in length/growth velocity which raised the question of the adequacy of the protein content in the diet. Since deviations from normal plasma amino acids have been observed in protein deficient, energy-adequate diets, we examined these parameters in the PKU children. In the two children with retardation in length/growth, very high glycine values as well as very high alanine values were observed at the end of the study. These observations strengthened our suspicion that the FAO/WHO 1973 recommendations are marginal.