Pure Encapsulations, 5-HTP 50 mg, 180 CapsulesPure Encapsulations 5 HTP Description Enhances brain serotonin (5 hydroxytryptophan) Hypoallergenic 5 Hydroxytryptophan (5 HTP) is an intermediate in the natural synthesis of the essential amino acid, tryptophan, to serotonin. The enzyme tryptophan hydroxylase adds a hydroxyl group (OH) to tryptophan, forming the 5 HTP intermediate. In the body, it converts to serotonin with the removal of a carboxyl group (COOH) by a second enzyme. Serotonin is an