Tyramine is a biological amine that exists in animals and plants. Tyrosine found in many foods can also be used to form tyramine, but its content gradually decreases when food begins to ferment. In its molecular structure, tyramine contains nitrogen from ammonia. Tyramine is found in relatively high levels in cheese, yeast, meat, fish, legumes and other foods, especially fermented or aged foods. In general, fresh food contains little or no tyramine. In addition, tyramine can also be found in the process of protein breakdown, such as tofu, soy sauce, soy milk and other soy products.
Modern food manufacturing processes can greatly reduce tyramine in foods, except for some cheeses and sauces. Tyramine content can be detected by liquid chromatography. Tyramine can be metabolized by intestinal monoamine oxidase after it is absorbed by us. Tyramine is the substrate of type I monoamine oxidase and also the substrate of DA transporter, vesicular monoamine transporter, NE transporter and trace amine-associated receptor 1.