Which amino acids are considered essential for neonates due to enzyme immaturity?

Which amino acids are considered essential for neonates due to enzyme immaturity?

• A. Taurine only
• B. Tyrosine only
• C. Taurine and Tyrosine
• D. Cysteine and Methionine

Answer: (C)

Neonates rely on dietary supply for certain amino acids because their enzyme systems for making them are immature, so these amino acids become essential despite not needing to be in the diet for adults. Tyrosine becomes essential because the enzyme that converts phenylalanine to tyrosine (phenylalanine hydroxylase) is not fully active in newborns, especially preterm infants. Without reliable conversion, tyrosine cannot be produced in sufficient amounts, so it must be supplied. Taurine also becomes essential as the enzymatic steps converting cysteine to taurine are underdeveloped in newborns. Taurine is important for bile acid conjugation and for normal retinal and neural development, making dietary taurine necessary in early life. The other options don’t reflect this dual requirement driven by enzyme immaturity. Taurine alone would miss the need for tyrosine, and tyrosine alone would miss taurine. Cysteine and methionine isn’t the typical neonatal pairing for this immaturity-driven essentiality, since methionine remains essential and cysteine is more often only conditionally essential.

Neonates rely on dietary supply for certain amino acids because their enzyme systems for making them are immature, so these amino acids become essential despite not needing to be in the diet for adults.

Tyrosine becomes essential because the enzyme that converts phenylalanine to tyrosine (phenylalanine hydroxylase) is not fully active in newborns, especially preterm infants. Without reliable conversion, tyrosine cannot be produced in sufficient amounts, so it must be supplied.

Taurine also becomes essential as the enzymatic steps converting cysteine to taurine are underdeveloped in newborns. Taurine is important for bile acid conjugation and for normal retinal and neural development, making dietary taurine necessary in early life.

The other options don’t reflect this dual requirement driven by enzyme immaturity. Taurine alone would miss the need for tyrosine, and tyrosine alone would miss taurine. Cysteine and methionine isn’t the typical neonatal pairing for this immaturity-driven essentiality, since methionine remains essential and cysteine is more often only conditionally essential.