Ask most people what a food allergy is and they will describe someone experiencing sudden difficulty breathing or breaking out in hives after ingesting certain foods such as peanuts or nuts. Those types of reactions are type 1 food allergies (immediate onset) that occur in only 2-5 percent of the population.
In contrast, the most common food allergies are “delayed onset” meaning the allergic symptoms are slower in appearing. In fact, reactions may take several hours to days to appear. Type 3 or delayed onset food allergies occur in 45-60 percent of the population. Yet, most people know little about this type of food allergy.
Similarities between Delayed and Immediate-Onset Food Allergies
Both types of food allergies involve the immune system and are in response to eating particular foods. Some of the reactions are similar but type 1 food allergies usually bring on immediate stomach cramping, diarrhea, skin rashes, hives, swelling, wheezing or anaphylactic shock. Individuals with type 3 food allergies may experience one or more of a 100 different reactions.
•In type 1 reactions, the immune system produces antibodies called IgE to certain foods while in type 3 food allergies, the antibodies are called IgG.
•Type 1 allergies are more common in children and rare in adults. Type 3 food allergies are seen equally in both children and adults.
•Type 1 allergies are easier to diagnose because reactions take place within two hours of eating. The slower-appearing type 3 responses make it more difficult to connect eating a particular food with an allergy. Type 3 food allergy sufferers may go years without knowing what causes their symptoms.
•Immediate-onset allergies usually involve one or two foods. Delayed reactions may involve 3-10 foods but in some cases, 20 or more foods.
•Type 1 allergies are usually self-diagnosed because of the immediacy of reactions. Type 3 allergies are difficult or sometimes impossible to self-diagnosis because of the slowness of reactions. Blood tests are often needed to detect type 3 allergies.
•Type 1 allergies are for life while type 3 can be reversed if certain foods are avoided for 3 or more months and not overeaten when reintroduced.