Tyrosine and phenylalanine are related and have been used as alternative remedies for depression.

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Scientists were able to control the enzyme by adding to it naturally occurring compounds, including one known as phenylalanine.

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The main phenylketonuria treatment is a strict diet with very limited intake of phenylalanine, which is mostly found in foods containing protein.

CNN: Phenylketonuria (PKU)

In general, the idea is to consume only the amount of phenylalanine that's necessary for normal growth and body processes, but no more.

CNN: Phenylketonuria (PKU)

L-Phenylalanine: L-Phenylalanine is an amino acid found in milk.

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This supplement may block some absorption of phenylalanine.

CNN: Phenylketonuria (PKU)