A new study reveals the significant size and burden of multiple food allergies in the United States. Among those with food allergies, about 46 percent of American adults and 40 percent of children have allergies to multiple foods, according to the research.
The study was conducted by Dr. Ruchi Gupta’s team at the Center for Food Allergy and Asthma Research (CFAAR) in Chicago. Her colleague and co-author Christopher Warren, PhD, was surprised by the overall high rate of allergies to multiple foods.
“Multi-food allergy is remarkably common and burdensome. It presents unique challenges for people living with it,” Warren told Allergic Living. He is the director of population health research for CFAAR, a center within Northwestern University’s Feinberg School of Medicine.
The study uses data collected on nearly 80,000 participants from across the United States. It also clearly identifies four clusters of food allergies that tend to go together.
From this general population survey, Gupta’s team published earlier pivotal work. In 2018, they estimated the prevalence of food allergies in U.S. children is 7.6 percent. Then their 2019 study of the data found 10.8 percent of U.S. adults have food allergies, a higher rate than previously known.
The team at CFAAR decided to dive deeper into the data gleaned from phone and internet surveys for 38,408 children and 40,443 adults. An obvious knowledge gap was: How many have multiple food allergies?
Analyzing the data on the 7.6 percent of kids and 10.8 percent of adults with food allergies, they discovered the respective 40 and 46 percent rates of allergies to multiple foods.
The public’s perception seems to be that most people with a food allergy are allergic to and avoiding one food, Warren says. But given the new findings, he says, “we should really be talking about multiple food allergies.”
Multiple Food Allergies: The Clusters
The data are based on patient or caregiver self-reporting. However, the study says strict criteria were used to include only those whose symptoms were consistent with “convincing” IgE-based food allergy, such as trouble breathing or vomiting.
To be classified as multi-food-allergic for this study, published in December 2022 in the Annals of Allergy, Asthma and Immunology, positive allergy tests were not enough. The participants had to have experienced an allergic reaction to more than one food, says Gupta, CFAAR’s founding director and a professor of pediatrics at Lurie Children’s Hospital and Northwestern Medicine.
The researchers classified people who are allergic to multiple tree nuts (such as cashew and walnut) as having multiple food allergies – since that is more than one food. The same applied to people who are allergic to different varieties of shellfish or fin fish.
The analysis found four common groups of allergens that often show up together in both children and adults with allergies to multiple foods:
- Milk / egg.
- Peanut / tree nut.
- Broadly multi-food-allergic.
For example, the study found that 61 percent of children with tree nut allergies are also allergic to peanut. Conversely, 33 percent of children allergic to peanut are also allergic to tree nut.
It was remarkable how clearly the data grouped the clusters, showing a general trend, says Warren, an assistant professor of preventive medicine at Northwestern Medicine. He says this closely mirrors what’s seen in the clinical setting.
“Identifying patterns is really important,” Gupta says. She says that knowing what food allergies go together can help with diagnosis, treatment research and guidance for managing allergies to multiple foods.
For example, knowing that a patient diagnosed with a milk allergy could be more likely to be allergic to egg may improve the efficiency and clarity of diagnosis, Warren says.
Burden of Allergies to Multiple Foods
The study finds that, as the number of IgE-based food allergies increases for a patient, so does the impact on quality of life. Warren notes, for instance, the steady climb in using the healthcare system and the emergency department.
The CFAAR data show the likelihood of reporting emergency department visits increased significantly with more food allergies. The study’s results include the following.
Visits to the ER over 12 Months:
- Nearly 14% of children with 1 food allergy.
- 24.6% of children with 2-3 food allergies.
- 30.5% of children with over 3 food allergies.
- 5% of adults with 1 food allergy.
- 9.6% of adults with 2-3 food allergies.
- About 19% of adults with over 3 food allergies.
The likelihood of reporting a severe allergic reaction and the use of an epinephrine auto-injector, also increased with the number of food allergies. For example, the study says adult patients with two to three food allergies had double the odds of having used an epinephrine auto-injector compared to those with one food allergy.
For patients with more than three food allergies, the odds of auto-injector use were triple. The increasing rates of epinephrine use corresponding to more food allergies were similar among children.
“It highlights that these people who are allergic to multiple foods are highly burdened,” Warren says.
What’s Meaningful, What’s Next?
The recent study notes that the rate of patients with multiple food allergies has been investigated in past, such as a review of pediatric charts that found 78 percent of 602 children showed signs of allergies to multiple foods. In 2011, a national food allergy prevalence study found that about 30 percent of children had multiple food allergies. That study classified tree nuts and shellfish as one allergy.
But this analysis is the first of its kind examining such a large scale of the general population, says Warren, who conducted the statistical analysis of the survey data.
Gupta says the goal of this analysis is to raise awareness, and to better inform future research, treatments and strategies for navigating life with multiple food allergies.
“Having one food allergy is hard, but having multiple allergies is harder,” she says. “How do we support that on a larger scale?”
Researchers are putting efforts into figuring out how to intervene early and to figure out effective strategies to guide food allergy patients, Warren says. Identifying patients who are at risk of developing other allergies and considering treatment therapies is one focus. Another is working to screen for psychosocial burdens and directing patients to mental health resources, he says.
More research into aspects of living with multiple food allergies is needed. The team at Northwestern is hoping to launch a more ambitious food allergy prevalence study that includes a clinical component to provide updated data, Warren says.
It is important to gather information about multiple food allergies, “so we can have a much better understanding,” Gupta says.