Phenylalanine is an essential amino acid from which the body builds proteins. It is similar to alanine and must be supplied through the diet.
Phenylalanine is the precursor of the amino acid tyrosine. From this in turn various catecholamines (e.g. epinephrine, norepinephrine), hormones and neurotransmitters (nerve messengers) such as dopamine are formed. If the body lacks phenylalanine, this leads to complex clinical pictures. Lack of hormones can lead to low mood, fatigue and pigmentation disorders, among other symptoms.
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