Although oranges and apples are consumed in similar quantities, intolerance to oranges is more commonly seen. This suggests that some commonly eaten foods have a higher ability to produce symptoms than others. Some people who are allergic to a certain type of fruit find that they can eat the same fruit if it has been through a process such as cooking, canning or even freezing. The allergens would appear to be modified by these processes, but the modification does not seem to help everyone. Canned fruit, especially strawberries and other berries, often contain large amounts of artificial chemicals including red colorant, added to preserve or enhance the visual appearance. Those sensitive to these chemicals may react if exposed to them.

Fruit is also frequently contaminated by pesticides and fungicides. Thiabendazole and other fungicides are used to prolong the storage life of oranges and lemons, and fruit should therefore be washed in hot soapy water, and thoroughly rinsed afterwards. Most forms of dried fruit have been preserved, and can be especially high in sulphur content. (Some speciality stores sell preservative-free dried fruit.) Fruit salad, glazed cherries, fruit juices, fruit pie fillings, fruit squash and fruit jellies are other possible sources of sulphur dioxide.

Papaya and pineapple both contain powerful protein-splitting enzymes that can damage the membranes of any cell, including those containing allergy-producing chemicals (mast cells containing histamine). This may cause them to spill their inflammatory content (called de-granulation) into the surrounding tissues. Mangos also appear to have a substance that can trigger mast cells, producing a so-called false-food allergy.

Some fruits like rhubarb, prunes and figs have a natural laxative effect, and may cause diarrhoea in susceptible individuals. Avocado pears may also occasionally be responsible for stomach upsets.