Now Foods 5-HTP 100 mg 120 Vcaps dietary supplement is extracted from the bean of an African plant called Griffonia simplicifolia. 5-HTP is an intermediate metabolite between L-tryptophan (an amino acid) and Serotonin. Serotonin is a neurotransmitter that relays signals between brain cells. Serotonin helps regulate mood and behavior. Taking 5-HTP as a dietary supplement may have a positive effect on sleep, mood, anxiety, appetite, and pain sensation.