SEATTLE -- One in four surveyed adults with food allergies reported developing their allergy after childhood, with women more likely to report an adult-onset food allergy than men, researchers reported here.
In more than 40,000 U.S. adults, the population-based analysis revealed that among adults with food allergies, 45.3% reported developing at least one food allergy after reaching age 18 years, according to Christopher Warren, a predoctoral fellow at the University of Southern California Keck School of Medicine in Los Angeles, and colleagues.
Of these respondents, 24.9% only experienced food allergy onset in adulthood and 54.7% only experienced food allergy onset in childhood, they reported in a presentation at the American College of Allergy, Asthma, and Immunology (ACAAI) annual scientific meeting.
The study is among the most comprehensive examinations of adult food allergy prevalence and characteristics ever conducted in the United States, Warren said.
"In the last few years, there has been a growing awareness about food intolerance issues in adults," Warren told Ƶ. "And we are certainly more aware of food allergies in kids, but we haven't had much data on food allergy prevalence in adults."
The survey was administered to 40,443 adults in the U.S. between 2015 and 2016, and population-level prevalence was estimated using complex survey weighting. Self-reported food allergies were validated by symptoms consistent with IgE-mediated reactions.
Shellfish allergy was the most common allergic reaction reported by adults (13.3%) with food allergies, followed by milk (6%), wheat (5.6%), tree nut (4.8%), and soy (3.9%).
"We were surprised by the prevalence of adult onset shellfish allergies," Warren said. "A substantial proportion ended up in the emergency department."
However, it was not clear from the survey findings if new-onset food allergies are increasing among adults. "That is hard to say because we really don't have the baseline data," Warren said. "This is really the first systematic look at the prevalence of food allergy in adults overall. It is also one of the first to examine how many developed allergies during adulthood."
Female sex and increasing age were both associated with an increased risk for an adult-onset food allergy, as was history of multiple food allergies, allergic rhinitis, or medication allergy.
"It is well described that people can develop new-onset food allergies as adults," said Anne Ellis, MD, of Queen's University in Kingston, Ontario, Canada. "But we don't really understand how it happens that some people can be fully tolerant of a particular food -- such as shellfish -- for many years, and then suddenly develop an allergy in their 30s, 40s, or even later in life."
Ellis, who was not involved with the study, told Ƶ that while there is still some mystery about why children develop food allergies, even less is known about why adults develop them.
"I'm glad to see researchers turning their attention to this to try to develop a better understanding of why this happens," she said. "Adult-onset food allergy is nowhere near as common as childhood-onset food allergy, but it is certainly an important area of study in addition to the much needed work that we continue to do in terms of childhood-onset food allergy."
Primary Source
American College of Allergy, Asthma, and Immunology
Warren C, et al “Prevalence, severity and distribution of adult-onset food allergy” ACAAI 2018; Abstract A311.