The process of serotonin production begins with L-tryptophan. First it is absorbed from the intestines to the bloodstream, where it is carried by proteins and in free form to peripheral sites. There it is used for protein synthesis, conversion to serotonin, and production of niacin. The tryptophan that is used in serotonin production is then hydroxylated into 5-hydroxy-tryptophan (5-HTP) by tryptophan hydroxylase, an enzyme which attaches oxygen molecules to form the hydroxyl. 5-HTP is converted to serotonin by an aromatic amino acid decarboxylase enzyme, which requires vitamin B6 to form the conversion.

Doctor's believe that by increasing the available 5-HTP, you can increase serotonin production. This would theoretically benefit those conditions that involve serotonin deficiency. Serotonin is one of the major neurotransmitters in the body. It plays a role in sleep, pain thresholds, blood flow, hunger/satiety, and libido. It is believed to play a role in depression, anxiety, and possibly obsessive-compulsive disorders.

Unlike tryptophan, 5-HTP cannot be degraded to kynurenine, nor can it be borrowed to enhance niacin production or used as a substitute in protein production. 5-HTP is dedicated to serotonin production alone, which means that supplemental 5-HTP are often more effective in treating serotonin related health problems than supplements of its precursor.