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Tyramine is a naturally-occurring compound often present in many plants and animals. It can also form from tyrosine — an amino acid found in a variety of foods — when those foods are fermented, or start to decay. It is known as an amine because of its molecular structure, which contains nitrogen, and is derived from ammonia.
In humans, this compound, also known as 4-Hydroxyphenethylamine, acts to release catecholamines — or the ‘fight or flight’ hormones — made by the adrenal glands into the bloodstream. Some of the substances that can be released include dopamine, norepinephrine — also known as noradrenaline — and epinephrine. When these hormones are in the bloodstream, systolic blood pressure and heart rate can rise.
This rise in blood pressure can often be dangerous for people who take monoamine oxidase inhibitors (MAOIs). Since the enzyme monoamine oxidase is the mechanism the human body typically uses to rid itself of excessive amounts of tyramine, if MAOIs are taken, tyramine levels may build up, leading to increased risk of a stroke. This is why many people taking MAOIs are advised to avoid foods containing tyramine.
Tyramine is also thought to have a possible causal connection to migraines in some people. Scientific studies, however, have provided mixed results. Supposedly, since it affects the vascular system through the release of catecholamines, it is thought to indirectly cause a constriction of blood vessels in the head. Then, as the effect wears off, the blood vessels dilate, which can potentially lead to a migraine occurring in individuals prone to them. Sometimes, if a migraine sufferer avoids foods containing tyramine, he or she may experience them less frequently.
Some of the foods that contain this compound include fermented foods, such as sauerkraut, soy sauce, and red wine. Others are aged foods, including hard cheeses like Parmesan, cheddar, and asiago, and cured meats, such as salami and some sausages. Additional foods high in tyramine include avocados, chocolate, fava beans, and pineapple, among others.
If a person is repeatedly exposed to it over a prolonged amount of time, tyramine can be converted to octopamine. This can occupy the same storage spaces in the human body, known as synaptic vesicles, that some of the catecholines do before they are used. It is thought that since octopamine somewhat replaces the fight or flight hormones, where they are usually stored, it may be responsible for a lowering of blood pressure, and possibly lead to a condition called orthostatic hypotension. This is sometimes seen in people taking MAOIs. More research needs to be done, however, to understand the role of octopamine in the human body.