Tyramine is a neurotransmitter and a derivative of tyrosine, a non-essential amino acid. Amino acids, of which there are 20, are the functional units making up a molecule of protein. Tyrosine is one of 11 amino acids that the body can synthesize on its own, making it a non-essential acid, while the remaining nine must be obtained from food sources and are known as essential amino acids. As tyrosine and subsequently tyramine are produced in the human body, so they are synthesized in the bodies of many plants and animals that humans consume as food. Therefore, there are many foods with tyramine, particularly those that are beginning to rot or spoil and those that are fermented. Examples of foods with tyramine include meats that have spoiled or been intentionally aged, cheeses and other fermented dairy, fermented soy products like soy sauce and tofu, and alcohol-containing beverages like wine.
As a derivative of this amino acid and a neurotransmitter, tyramine is classified as a releasing agent, specifically of catecholamine neurotransmitters like epinephrine, norepinephrine, and dopamine. In other words, tyramine is a substance that induces the release of chemicals from a neuron, or nerve cell, and sends it along to adjoining neurons via an electrical-signal-conducting junction between each cell called a synapse. An accumulation of these chemicals in the cells as occurs after consuming foods with tyramine produces a specific response ® this is the same process that occurs when drugs are introduced into the body.
The consumption of foods with tyramine such as aged meats and cheeses can temporarily produce a mild metabolic reaction as increased amounts of dopamine and epinephrine, better known as adrenaline, are released. This response may include a slight increase in heart rate and blood pressure. An enzyme called monoamine oxidase then comes along and metabolizes tyramine, or breaks it down into its molecular components for use by the body, which in turn halts the release of the neurotransmitters and allows the heart rate and blood pressure to return to normal levels.
In fact, when large amounts of food with tyramine are consumed by a person who is also taking monoamine oxidase inhibitors (MAOIs), drugs that are prescribed to treat depression, it can produce a response known as the “cheese effect.” This is a hypertensive crisis, or sudden and dangerous increase in blood pressure, brought on by the combination of MAOIs, which block the breakdown of neurotransmitters like dopamine by monoamine oxidase, and tyramine, which increases levels of many of the same neurotransmitters in the body. A technical term for this reaction is the tyramine pressure response, which can cause the systolic blood pressure to rise by upwards of 30 millimeters of mercury (mmHg).
As such, a person on MAOIs may want to limit her consumption of foods with tyramine. These include meats like beef, pork, fish, and chicken, especially those that have begun to spoil or are aged. Other typramine-rich foods include aged cheeses like Stilton, yogurt and sour cream, and soy-based condiments and sauces. Plant-based foods to avoid are several kinds of beans and pea pods like green beans and snow peas, and several high-sugar fruits like bananas, figs, and pineapples, particularly as they ripen. The reason that tyramine levels go up as food ages is that the decay process causes tyrosine molecules to break down and release carbons, which in turn produces tyramine as a derivative.