The public believes that some 20-25 percent of people have food allergies. This may actually be low if you consider both IgE and IgG mediated reactions. If you only consider IgE (atopic) food allergies, the numbers are much lower, with one to two percent of adults having this reaction and six to eight percent of infants/children having such response. Among adults, the most severe response is to peanuts and tree nuts. Among children, the offending food item is primarily milk. The bad news for children is that they often have more skin reactions to foods, such as eczema, than do adults.
However, the good news for the young patient is that a child often outgrows his or her food sensitivities, even those that are positive on a RAST test. Food allergies may fade, and then inhalant (e.g, dust, ragweed) allergies may begin to manifest. This progression from food allergies to inhalant allergies and then finally asthma is often termed “The Allergic March”.
Non-atopic (IgG mediated) food allergies are difficult to diagnose and treat. They also are more prevelent and problematic in our culture. We are always keeping pace with what legitimate options exist for our patients.