noun Download 🔗Share An essential amino acid C9H11NO2 found in most animal proteins; it is essential for growth; the inability to metabolize it leads to phenylketonuria; it is a constituent of aspartame. Examples : "Example sentence: "People with phenylketonuria (PKU) must carefully limit their intake of phenylalanine from foods like meat and dairy to prevent health problems." " biochemistry medicine chemistry biology substance compound physiology food Chat with AIVocabulary GamePractice Reading