Several endogenous biogenic amines, which act as sympathomimetic compounds, are found in chocolate, most notably, tyramine and phenylethylamine (PEA). PEA, a neuromodulator of brain synapses, is structurally and pharmacologically similar to catecholamines and amphetamine. On a normal basis, PEA is heterogeneously distributed within the central nervous system (CNS), and at physiological doses it may act to potentiate dopaminergic and noradrenergic neurotransmission. PEA is produced by brain tissue and is rapidly metabolized by monoamine oxidase-β (MAO- β) and aldehyde dehydrogenase to phenylacetic acid, the major metabolite of PEA in the brain. Studies have demonstrated that PEA is pharmacologically active and that it is stimulatory when administered.
Although PEA is highly lipid soluble and crosses the blood-brain barrier against a concentration gradient, biochemical evidence for high affinity and saturable binding sites for PEA in the brain has yet to be solidified.