Maois Interactions

Fermented foods accumulate tyramine when bacteria break down the amino acid tyrosine during fermentation. MAOIs block the monoamine oxidase enzyme that normally clears dietary tyramine in the gut wall and liver, so the tyramine reaches the bloodstream and triggers a surge of norepinephrine. This can produce a sudden, dangerous rise in blood pressure (a hypertensive crisis).

Yerba mate is a caffeine-rich infusion. On a non-selective MAOI (phenelzine, tranylcypromine, isocarboxazid), the enzyme that normally clears tyramine and tempers sympathetic tone is blocked, so a high caffeine and methylxanthine load plus any tyramine the brew carries can amplify the pressor response and push blood pressure into dangerous territory. The yerba-mate-specific risk is extrapolated from documented caffeine-plus-MAOI cases, not from direct mate studies.

Nutmeg contains myristicin, which a 1963 laboratory study reported to weakly inhibit monoamine oxidase (MAO) in vitro. Because MAOI antidepressants block the same enzyme, the theoretical concern is an additive effect, though no human cases are documented.

Raw or ceremonial cacao carries a somewhat higher load of biogenic amines such as tyramine than fully processed chocolate. Dietary analyses show that the tyramine content of cocoa and chocolate is generally low, and there is no documented human case of a hypertensive crisis from cacao on a monoamine oxidase inhibitor (MAOI). The sensible approach is moderation with raw or ceremonial cacao rather than blanket avoidance, reviewed with your prescriber.