of a food allergen. Patients whose EIA is food-dependent are thought to make up from one third to a half of all EIA cases. In a 2001 study of 76,229 Japanese junior high students, 0.017% of students were found to suffer from the condition. In European countries, the most common trigger foods for FDEIA are tomatoes, cereals and peanuts. In Japan, FDEIA is most commonly triggered by omega-5-gliadins, an allergen found in wheat. Other common foods thought to be linked to FDEIA include shellfish, seeds, dairy (in particular cow's milk), fruits and vegetables (such as grapes, onions and oranges), meats, and even mushrooms. Ingestion of the trigger food most often precedes exercise by minutes or hours in cases of an attack; there are, however, reported incidents of attacks occurring when ingestion transpires shortly following activity. While a lot remains unknown about the pathophysiology of food-dependent exercise-induced anaphylaxis (FDEIA), one theory points to changes in pH; this theory is based on the fact that pH becomes more acidic in the muscles and serum following exercise. Decreasing pH is associated with an increase in mast cell degranulation, a key component to the immune response, and one study found that, when patients with FDEIA are given the antacid sodium bicarbonate prior to exercise, they do not experience FDEIA symptoms. Common triggers Exercise-induced anaphylaxis is most commonly brought on by aerobic exercise. It is most often caused by higher levels of exertion, such as jogging, but can be brought on by milder activities, such as a gentle walk. In a 1999 study, 78% of sufferers reported that attacks were frequently caused by jogging, whereas 42% reported symptoms following brisk walking. There are several factors outside of food and exercise that have been suggested to increase the risk of an EIA attack. These include the consumption of alcohol, exposure to pollen, extreme temperatures, the taking of non-steroidal anti-inflammatory drugs (NSAIDs), and even certain phases of the menstrual cycle. Pathophysiology The pathophysiology surrounding EIA and FDEIA is not yet fully understood, but there are several theories. Research shows that histamine, a chemical involved in the allergic response, plays a key role in EIA. Increased histamine levels in the blood plasma have been recorded during incidents of both EIA and FDEIA. Morphological changes in mast cells in the skin of EIA patients have been observed following exercise, and are comparable to changes occurring in atopic patients following