Contributed by IFM Faculty Member Kara Fitzgerald, ND
IgE-mediated food allergies, the ones that can cause anaphylaxis, have historically been relatively rare. They primarily occurred in kids, who tended to outgrow them by adulthood. Recently, however, we have seen a rise in the incidence of these allergies in children, and the reactions increasingly are sustained into adulthood. Furthermore, we’re seeing new-onset food allergies and anaphylaxis in adults, something that was virtually unheard of a mere 20 or 30 years ago. So what factors are contributing to this onslaught of allergic disease?
One powerful shift that is promoting adult-onset food allergy is the relatively new, global use of acid blocking therapy such as PPIs and H2 blockers. A number of studies clearly demonstrate this association, including one completed in 2005 by Untersmayr, et al.1 In this trial, 152 adults were given either a PPI or H2 blocker for three months and IgE responses to 19 foods were measured at the end of the trial. Amazingly, there was a greater than 10-fold rise in the incidence of food allergy in the study group as measured by IgE response. Not surprisingly, a control group demonstrated no significant change in IgE food allergy incidence. The majority of these food allergies were de novo, or new onset reactions. Some patients with existing allergies experienced an increase in intensity of the reaction as a result of the drugs. In a significant subset of individuals, the reactions continued long after the acid blockers were stopped.
The mechanism of this reaction is straightforward: acid blockers inhibit digestion of protein in the stomach. When the stomach does not pre-digest protein for the intestine, the pancreatic and brush border enzymes found there don’t work as well, resulting in larger protein fragments that are sometimes absorbed. Larger protein fragments are more antigenic and therefore more likely to generate an allergic response.