Earlier prevalence estimates that have found the range of food allergies as high as 8 percent in children under age 3, but more in the range of 4 percent for older children.
Gwen Smith, Allergic Living magazine’s editor, spoke to Dr. Ruchi Gupta, the lead author of the study, about her findings and what they mean. Her study was published in the journal Pediatrics and funded by the Food Allergy Initiative.
Gwen Smith: In your study you found that 8 percent of children under 18 have food allergies. We’re used to hearing a figure much lower than that for kids over the age of 3 or 4. What do you make of your larger statistic?
Dr. Gupta: It is a large figure, about two kids in every classroom. In practical terms it makes sense, though. I think most parents when they look around their child’s classroom are seeing one or two kids with food allergies, maybe more. I don’t know if it’s a big surprise – since I see it in my own daughter’s classroom and this is true for everyone [parents of patients] that I talk to. I think it’s just getting a good solid number that represents what’s going on in the United States, and that’s what we did.
If you’re wondering if this represents an increase, I don’t really think there’s been a big [recent] one. I know there have been a variety of numbers, there was a report in JACI [Journal of Allergy and Clinical Immunology] of between 1 and 10 percent, so there is a huge range that has been talked about.
GS: But it gets confusing since, while your number is higher, a government agency not long before pegged the prevalence among older children at just under 4 percent.
[Dr. Gupta explains that methodologies are different and that may partly explain. For instance, when the Centers for Disease Control and Prevention came out with the estimate of 3.9 percent of children having a food allergy, they were using a wide-ranging questionnaire on all sorts of diseases, with one food allergy question along the lines of: “does your child have a food allergy or digestive disorder in the past year?”]
Dr. Gupta continues: The CDC report was good, every time we get something we have a little bit more information.
GS: So what was the difference with your study?
Dr. Gupta: What we tried to do was a large, nationally representative study asking only about food allergy. That’s why I feel so confident in what we have produced because it was only for food allergy and we did it on a national level. The number that we have of 8 percent is a very solid number. We took into account families that stated that they may have an allergy to a food and we looked at their reactions. We ended up taking out about 2 1/2 percent of the kids who we thought may actually have intolerances and not allergies. We didn’t just go off a ‘yes, my child has a food allergy’ answer or if we had our results would have been closer to 10½ percent.
We thoroughly reviewed the results with an expert panel to make sure that what we were looking at, based on the history the parents gave us, was true food allergy. The study is carefully done and it looks at all food allergy, not a specific food allergy, so I have a lot of confidence in the numbers.
We did ask, not only ‘does your child have a food allergy,’ but also which allergy and, for each food they reported, we went into: who diagnosed it, how was it diagnosed, what reactions have they [the children] had from ingesting the food in the past. It was a detailed survey that a parent had to fill out.
GS: You had close to 40,000 general households in your survey – not just households where there was known allergy.
Dr. Gupta: Oh yes, general households.
GS: So as a parent, I then answered a bunch of questions. What was the process from there?
Dr. Gupta: Just to back up a little. We’d ask you how many children do you have, and, say, the answer was three, we’d say: ‘OK, so we want you to answer the rest of the questions about Child No. 2.’ So we randomly selected a child in the household. If you ask if any child in the household has food allergies, then you’re inflating your numbers because you want just a random selection of children. If in this example, the parent answered that ‘no, the No. 2 child doesn’t have food allergies,’ then we were pretty much done. [If the parent said yes, then they would be taken through the details above about who and how tested, including what kinds of tests, and for details of reactions.]
GS: It sounds like you collected a lot of detail. Will there be more studies emanating from this data?
Dr. Gupta: We got a pretty substantial amount of data from the parents on each individual food a child was allergic to. The next paper we’ll write is on geographic variability because we had the zip codes of where these people lived. So we’ll be able to look at food allergy by state level.
GS: Can you give us a hint? Any north-south divide?
Dr. Gupta: [Laughs] Not yet!
GS: In the study, you say that African-American and Asian-American children are more likely to have food allergic reactions. Any insights into why that is?
Dr. Gupta: This is very interesting to me. [As with asthma, which she also studies,] we saw a much higher chance of African-American children having food allergies [and reactions]. But, there was a lower chance of being diagnosed with food allergy. My thoughts on this is that, unlike asthma, we don’t have any medicines to control food allergies so if they [parents] have only seen a mild reaction, they just try to avoid the food [but don’t get an auto-injector].
Other reasons are that they may not be insured or they may not have access to an allergist.
We are going to go into pediatric offices in the fall (2011) to see how many parents have children with food allergies, and how many have not discussed that with their primary care doctors. We want to get a sense of what the barriers are. We’re going to try to see where this disconnect is.
GS: Another high percentage in your study relates to the number of children having serious food-allergic reactions. It was just under 39 percent. What can you tell us about that finding?
Dr. Gupta: It is a lot of kids, that’s about 2 out of every 5 kids with food allergy showing a severe food allergy. It’s not that they have a severe food allergy, it’s that they’ve had a severe food-allergic reaction. That doesn’t mean that the other 3 [out of 5] kids do not have a severe food allergy, it just means that they haven’t either been exposed or maybe they don’t have as severe an allergy, but 2 out of 5 have already experienced a severe or life-threatening reaction. And that’s definitely a very high number.
GS: So might more than 39% have a severe allergy?
Dr. Gupta: Yes. But even to say that almost 40 percent have experienced a reaction makes a very strong point that is that people need to understand how severe a food allergy can be. I think in the general public, people often don’t get that this is something that could take a life. With these kids, it’s not just breaking out in hives or a rash, but this is difficulty breathing, throat closing, drops in blood pressure, really severe reactions that could take a child’s life if not treated appropriately and quickly. So I think that is a really big message in this paper.
GS: It’s interesting to look at your findings because I’m so used to seeing repeated suggestions that, because there are so many false-positive blood or skin tests, the numbers for food allergy may be inflated. But your numbers are higher than the ones being tempered by such concerns. How do you reconcile this?
Dr. Gupta: In our study, if someone said their child tested positive to, say, peanuts, but never had a reaction, they were not included in our final numbers. We didn’t leave them out, but they were in that 2 ½ percent that we weren’t sure about. Maybe they could have a reaction, but if they haven’t, we cannot count it. We didn’t have too many people reporting in that direction.
GS: You saw quite a high rate of shellfish allergy in kids, which we usually think of as an adult allergy. Did that surprise you?
Dr. Gupta: I wouldn’t say that I was shocked, but it is high. The Top 8 allergens are still the Top 8 but in a different order. Peanut we would assume was big, but milk being right on its heels was interesting ….
GS: Because you are talking about children up to 18 years old, not just the young ones.
Dr. Gupta: That’s right, absolutely. And then for shellfish to come right after that, I did think that was interesting – but I don’t know about surprising. [laughs] I think the results made me feel comfortable that what I was seeing in my clinic, in my neighborhood, in my society, was in fact what was going on in the country.
GS: You’re certainly busy with these studies.
Dr. Gupta: We are! But what’s great is that people are now engaged and they want to know about food allergies. And I get support for this work that I feel so passionate about. Hopefully, we’ll have a lot more answers in a year than we do today.
GS: Thank you very much for sharing your insights, Dr. Gupta.
Dr. Gupta: My pleasure.
Dr. Gupta is a pediatrician at Children’s Memorial Hospital in Chicago and assistant professor of pediatrics at Northwestern University’s Feinberg School of Medicine.
Find the study in Pediatrics here.
Dr. Gupta’s 2018 study on food allergy in U.S. children. Of note: high prevalence of peanut and milk allergy, shrimp allergy rises in children.
The Gupta team’s 2019 study of food allergy prevalence in adults. Of note: far higher prevalence than previously known; suggests 32 million Americans have food allergies.