Tyramine is a naturally occurring trace amine derived from the amino ace tyrosine. Tyramine acts as a catecholamine releasing agent. Tyramine occurs widely in plants and is food in considerable amounts in fermented foods such as aged or smoke meats, chocolate, alcoholic beverages, and cheeses, especially Stilton. It is metabolized by monoamine oxidase so use of monoamine oxidase inhibitors and subsequent ingestion of tyramine-rich foods can cause a hypertensive crisis. This effect is sometimes demonstrated by the presence of a headache after eating cheese.