Monoamine oxidases metabolise tyramine, an uncommon amino acid found in cheese. When a monoamine oxidase inhibitor is present alongside tyramine, monoamine neurotransmitters are displaced from their vesicles. This increases the levels of noradrenaline, dopamine, and adrenaline present.
By increasing the presence of monoamine neurotransmitters, hypertension occurs, elevating blood pressure. This is due to noradrenaline inducing vasoconstriction.
Therefore, patients prescribed monoamine oxidase inhibitors must avoid eating foods containing tyramine (including cheese etc…)