NOW NOW 5-HTP (5-hydroxy L-tryptophan), 200 mg x 60 herbal capsules5 HTP (5 hydroxy L tryptophan) is a naturally occurring metabolite. 5 HTP serves as an intermediate for the amino acids L tryptophan and serotonin. Under normal conditions, the optimal level of serotonin in the body is maintained by its production of these metabolites. Serotonin is a neurotransmitter that transmits nerve impulses between neurons with serotonin receptors. Serotonin plays a role in the processes of regulating sleep, mood, appetite or