Foods that are riper or have been longer standing tend to have higher tyramine content than fresh or freshly-prepared foods. Thus a piece of fruit that is fresh and firm may be well tolerated, but a ripe or especially over-ripe piece of the same food may provoke a serious reaction. Furthermore, bacterial action on protein sources such as meat and soy products can cause an increase in the food's tyramine levels. In summary, the caution regarding foods high in tyramine is that firm and fresh is more likely to be safe than over-ripe or over-exposed to potential bacterial overgrowth. High tyramine-containing foods
Items in the list below that are bolded contain high to very high amounts of tyramine.

• Aged cheese: american, processed, blue, boursault, brick (natural), brie, camembert, cheddar, emmenthaler, gruyere, mozzarella, parmesan, romano, sour cream, roquefort, stilton and swiss.
• Aged, cured or spoiled meats: beef or chicken liver, other meats, fish (unrefrigerated, fermented), fermented sausages (bologna, pepperoni, salami, summer sausage), game meat, meat tenderizer, meat extracts, caviar, salted herring and other dried fish, pickled herring (spoiled) and shrimp paste.
• Alcohol: ale, beer (including some non-alcoholic beers), red wine (especially chianti), port, reisling, sauternes, sherry, vermouth and distilled spirits.
• Fruits/vegetables: avocados (especially overripe), bananas, bean curd, (fava) bean pods, canned figs (overripe), miso soup, red plums, raisins, sauerkraut, soy sauce, soy bean condiments, spinach, teriyaki, tofu, tomatoes and yeast and yeast extracts (marmite, brewer's yeast and baker's yeast.
• Other items with similar actions: chocolate (cocoa) and caffeine (coffee, tea, colas).

Analysis of pizzas from large chain commercial outlets found no significant tyramine levels in any of the pizzas tested, including those with double pepperoni and double cheese. Marked variability was found with soy products, including significant amounts of tyramine found in tofu when stored for a week, and high tyramine content of some soy sauces. The
authors of this study concluded that pizzas from large chain commercial outlets are safe for consumption with MAO inhibitors. However, they recommended caution when ordering from smaller outlets or with gourmet pizzas that may use aged cheeses. All soybean products should be avoided.