Phenylalanine is an essential amino acid and cannot be manufactured by the body. Phenylalanine has a role as a precursor for norepinephrine, this means it may help stimulate energy. Persons suffering from chronic fatigue may benefit from this ability. A deficiency of dopamine may cause mood lows (possibly depression or anxiety), L-phenylalanine is a precursor to neurotransmitters which include dopamine. DLPA may be supportive in pain relief as it plays a role in the synthesis of endorphines in the body. DLPA may also contribute to appetite supression.