Final answer:
The claim that phenylalanine levels must be kept within a specific range to prevent protein catabolism and promote growth is false for infants with Phenylketonuria (PKU). Instead, those with PKU require a strict low-phenylalanine diet to prevent neurologic damage.
Step-by-step explanation:
The statement regarding the infant's blood level of phenylalanine needing to be kept below 8 mg/dL to prevent protein catabolism and above 2 mg/dL to promote growth and development is false. Phenylalanine is an amino acid that becomes toxic when its concentration is too high due to a condition known as Phenylketonuria (PKU). People with PKU lack sufficient activity of the enzyme phenylalanine hydroxylase and cannot adequately convert phenylalanine into tyrosine, leading to an accumulation of phenylalanine which can cause central nervous system and brain damage. For individuals with PKU, maintaining very low levels of phenylalanine in the blood is crucial to prevent damage, especially since the early stages of development are critical. Infants diagnosed with PKU must adhere to a strict diet low in phenylalanine to avoid its toxic buildup and promote normal development.
It's important to note that while maintaining certain levels of phenylalanine is necessary for individuals who do not have PKU, for those afflicted with PKU, these levels must be carefully monitored and kept low. In the broader context, phenylalanine is found in various foods, and individuals with PKU, especially infants and pregnant women, must avoid high-phenylalanine foods and artificial sweeteners like aspartame to mitigate the risks posed by this metabolic disorder.