Individuals with PKU need to restrict their intake of which amino acid?

Phenylketonuria (PKU) is a genetic disorder characterized by the absence or deficiency of the enzyme phenylalanine hydroxylase, which is responsible for converting phenylalanine into tyrosine. When individuals with PKU consume phenylalanine, it accumulates in their body and can lead to serious neurological damage and cognitive impairment.

To manage this condition, individuals must adhere to a strict dietary restriction of phenylalanine, which is an amino acid found in many protein-rich foods. By limiting phenylalanine intake, patients can prevent the harmful effects associated with its accumulation and maintain normal growth and development.

Tyrosine, on the other hand, is produced from phenylalanine, and because PKU patients often have low levels of tyrosine due to the impaired conversion, they may need to monitor its levels, but it is not restricted in the same way. Glutamate and lysine are not directly involved in the pathology of PKU and thus do not need to be restricted.