Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Phenethylamine (PEA) is a natural monoamine alkaloid, trace amine, and psychoactive drug with stimulant effects. In the mammalian central nervous system, phenethylamine is believed to function as a neuromodulator or neurotransmitter. It is biosynthesized from the amino acid phenylalanine by enzymatic decarboxylation. Besides mammals, phenethylamine is found in many other organisms and foods such as chocolate, especially after microbial fermentation. It is sold as a dietary supplement for purported mood and weight loss-related therapeutic benefits; however, orally ingested phenethylamine is usually inactive on account of extensive first-pass metabolism by monoamine oxidase (MAO) into phenylacetic acid, preventing significant concentrations from reaching the brain.