tyramine

Tyramine is a naturally occurring monoamine compound derived from the amino acid tyrosine. It is classified as a trace amine and chemically known as 4-hydroxyphenethylamine (p-hydroxyphenethylamine) with the formula C8H11NO. Tyramine is produced in the body by decarboxylation of tyrosine and is also generated by certain gut bacteria during the fermentation and aging of foods.

In the body, tyramine acts as a releasing agent for norepinephrine, promoting its release from sympathetic nerve terminals. This can cause vasoconstriction and a rise in blood pressure. Tyramine is normally metabolized rapidly by monoamine oxidase A (MAO-A) in the gut and liver. When MAO activity is inhibited, as with certain antidepressants (MAO inhibitors), tyramine can accumulate and trigger hypertensive crises due to excessive norepinephrine release. Tyramine metabolism may involve subsequent oxidation to p-hydroxyphenylacetaldehyde and further breakdown.

Dietary sources contain varying tyramine levels. High-tyramine foods include aged cheeses, cured or fermented meats, certain pickled or smoked products, soy products (such as miso, soy sauce), and some fermented beverages like beer and red wine. Tyramine levels also rise in overripe or spoiled foods. Fresh, properly stored foods are typically low in tyramine.

Clinically, tyramine sensitivity is most notable in patients taking MAO inhibitors, who are advised to limit high-tyramine foods to avoid hypertensive episodes.