5-HTP is used by the human body to make serotonin, an important substance for normal nerve and brain function. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions. 5-HTP is not present in significant amounts in a typical diet. The human body manufactures 5-HTP from L-tryptophan, a natural amino acid found in many dietary proteins. However, eating food that contains tryptophan does not significantly increase 5-HTP levels. Supplemental 5-HTP is naturally derived from the seeds of the Griffonia simplicifolia, a West African medicinal plant.