Phenylalanine estimated requirements

Abnormally high levels of phenylpyruvate and phenylacetate damage developing brain cells, causing severe mental retardation. It is estimated that 1 out of every 20,000 newborns is afflicted with PKU. A federal regulation requires that all infants be tested for this disease, which can be detected very easily by analyzing blood or urine samples for phenylalanine or phenylpyruvic acid. 

Determine amount of breast milk required to provide the infant s estimated phenylalanine needs. Determine the amount of protein and energy that will be provided by this volume of breast milk. 

The latter value is not much above the estimate of 27 mg per kg per day for phenylalanine plus tyrosine obtained by Nakagawa et al. (1961-1963). The latter values as summarized by the FAO/WHO Committee are shown in Table 2 together with the concentration required in the dietary protein if the requirement is 0.8 gm per kg per day. 

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