Phenylalanine is an essential amino acid which is highly concentrated in the human brain and plasma. Phenylalanine is a precursor for Tyrosine and these two amino acids are used by the brain to manufacture neurotransmitters.

The great uplifter!...L-Phenylalanine is an essential amino acid which is highly concentrated it the human brain and plasma. Phenylalanine is a precursor for Tyrosine and these two amino acids are used by the brain to manufacture neurotransmitters.