Anaphylaxis occurs when IgE antibodies are involved, and areas of the body that are not in direct contact with the food become affected and show symptoms. Those with asthma or an allergy to peanuts, tree nuts, or seafood are at greater risk for anaphylaxis. Causes
Although sensitivity levels vary by country, the most common food allergies are allergies to milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat. These are often referred to as "the big eight". Allergies to seeds—especially sesame—seem to be increasing in many countries. Sesame will join “the big eight” as a priority allergen in the United States by 2023. An example of an allergy more common to a particular region is that to rice in East Asia where it forms a large part of the diet.One of the most common food allergies is a sensitivity to peanuts, a member of the bean family. Peanut allergies may be severe, but children with peanut allergies sometimes outgrow them. Tree nuts, including almonds, brazil nuts, cashews, coconuts, hazelnuts, macadamia nuts, pecans, pistachios, pine nuts, and walnuts, are also common allergens. Affected individuals may be sensitive to one particular tree nut or to many different ones. Peanuts and seeds, including sesame seeds and poppy seeds, can be processed to extract oils, but trace amounts of protein may be present, and elicit an allergic reaction.Egg allergies affect about one in 50 children but are frequently outgrown by children when they reach age five.
Does the amino acid sequence of the transferred proteins resemble the sequence of known allergenic proteins? Are the transferred proteins resistant to digestion - a trait shared by many allergenic proteins? Genes approved for animal use can be restricted from human consumption due to potential for allergic reactions. In 1998 Starlink brand corn restricted to animals was detected in the human food supply, leading to first a voluntary and then a FDA mandated recall. There are requirements in some countries and recommendations in others that all foods containing GMO ingredients be so labeled, and that there be a post-launch monitoring system to report adverse effects (much there exists in some countries for drug and dietary supplement reporting). Restaurants
In the US, the FDA Food Code states that the person in charge in restaurants should have knowledge about major food allergens, cross-contacts, and symptoms of food allergy
reactions. Restaurant staff, including wait staff and kitchen staff, may not be adequately informed about allergenic ingredients, or the risk of cross-contact when kitchen utensils used to prepare food may have been in previous contact with an allergenic food. The problem may be compounded when customers have a hard time describing their food allergies or when wait staff have a hard time understanding those with food allergies when taking an order. Diagnosing issues
There exists both over-reporting and under-reporting of the prevalence of food allergies.