Which dietary component is restricted in the typical PKU management plan?

Which dietary component is restricted in the typical PKU management plan?

• A. Phenylalanine
• B. Tyrosine
• C. Tryptophan
• D. Leucine

Answer: (A)

In PKU, the body can’t properly convert phenylalanine into tyrosine because the enzyme is deficient, so phenylalanine builds up and can harm brain development. To prevent this, the diet is designed to limit phenylalanine intake from all protein sources. As a result, phenylalanine is the dietary component that is restricted. Because phenylalanine isn’t adequately produced from this restricted intake, tyrosine becomes essential and is often added through supplementation or medical foods. The other amino acids aren’t the primary targets of restriction in standard PKU management.

In PKU, the body can’t properly convert phenylalanine into tyrosine because the enzyme is deficient, so phenylalanine builds up and can harm brain development. To prevent this, the diet is designed to limit phenylalanine intake from all protein sources. As a result, phenylalanine is the dietary component that is restricted. Because phenylalanine isn’t adequately produced from this restricted intake, tyrosine becomes essential and is often added through supplementation or medical foods. The other amino acids aren’t the primary targets of restriction in standard PKU management.