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Why Are Food Allergies on the Rise? with Ruchi Gupta, MD, MPH

There’s been an uptick in childhood food allergies in recent years, and new evidence from Northwestern shows they’re also becoming more common in adults. Many of the reactions to these allergies are life-threatening. Why is this increase happening, and how can we keep people affected by food allergy safe? Ruchi Gupta, MD, MPH, is trying to answer those questions.

Ruchi S. Gupta, MD, MPH

"We found that about half, 48 percent, said they developed at least one new food allergy as an adult that they didn't have as a child. Those numbers were a little astonishing. Additionally, about one in four adults said they developed an allergy is an adult and never had a food allergy as a child.”

Ruchi S. Gupta, MD, MPH

  • Director, Center for Allergy and Asthma Research
  • Professor of Pediatrics in the Division of Academic General Pediatrics and Primary Care
  • Professor of Medicine in the Division of Allergy and Immunology

Episode Notes

Over the past decade, Ruchi Gupta and other scientists who study food allergies have published a great deal about the rise of childhood food allergies. The data was groundbreaking and has led to a greater understanding of food allergies, the risk of anaphylactic reaction and death and the importance of having epinephrine in schools as a life-saving tool.

  • While awareness has increased around children with food allergies, there has been very little data on adults with food allergies. However, anecdotally, Gupta had heard about an increase in adult on-set food allergies. She decided to investigate the issue.
  • Ruchi Gupta: "Since we had the expertise in doing large-scale prevalence studies, we thought we would modify our pediatric study for adults and really understand how many people in the United States are affected by food allergy and what that looks like."
  • The study, based on a nationally representative survey of more than 40,000 adults, was published in JAMA Network Open. It found 10 percent of adults in the U.S. — over 26 million — are estimated to have food allergy. About half of those said they developed at least one new food allergy as an adult that they didn't have as a child.
  • Ruchi Gupta: "Those numbers were a little astonishing. Additionally, about one in four adults said they developed an allergy as an adult and never had a food allergy as a child. So that's a lot of adults developing new allergies."
  • Shellfish was the most common adult food allergy reported — nearly 3 percent of adults studied reported an allergy. Milk and peanuts were the second most common at around 2 percent each. There are many theories as to why food allergies are on the rise in both adults and children, but Gupta says there is no definitive answer.
  • Ruchi Gupta: "Chances are there is not one factor ... it's going to be a group of factors and how our lifestyles have changed. The one big breakthrough that's happened is there was a large study done in London called the LEAP Study, and they found that if you feed infants, high-risk infants, peanut products early in life, that you may be able to prevent peanut allergy. So that exposure through the gut early could be preventive. This was a really big breakthrough because for the first time we have a way to potentially prevent it."
  • Gupta's own daughter was diagnosed with food allergies and has inspired her to continue research and raising awareness about the issue. She created a series of videos for elementary-aged children to discourage bullying of children with food allergies and develop more peer understanding and peer support.

Additional Reading and Resources:

  • Watch Gupta's food allergy educational videos.
  • Gupta wrote a book titled "Food Without Fear", which dives deeper into the theories behind food allergy development, explains the differences between food allergy, intolerances, and sensitivities, and provides several tools for understanding and managing food-related conditions.
  • Since 2019, there have been several follow-up papers stemming from this data, specifically about shellfish prevalence in adults and children and its connection to cockroach and dust mite sensitization.
  • In 2020, Palforzia was approved by the FDA for the treatment of peanut allergy.
  • More updates can be found at the Center for Allergy and Asthma Research's 2022 Annual Report.

This episode was originally published on February 12, 2019, and republished on January 17, 2023.

Erin Spain: This is breakthroughs, the podcast from Northwestern University Feinberg School of Medicine. I'm Erin Spain, executive editor of the Breakthroughs newsletter. There's been an uptick in childhood food allergies in recent years, and new evidence from northwestern shows that food allergies are also becoming more common in adults. Many of the reactions to these allergies are life threatening. Why is this increase happening and how can we keep people affected by food allergy safe? Dr. Ruchi Gupta is trying to answer those questions. She's dedicated her career to food allergy and asthma research here at Northwestern and the Ann & Robert H. Lurie Children's Hospital of Chicago where she's an attending physician. Her work is debunking myths and shaping policies around food allergy. Thanks for joining me today.

Ruchi Gupta: So glad to be here. Thank you.

Erin Spain: You're an expert on childhood food allergies and asthma. Leading much of the current research on this topic, but your most recent paper and JAMA Network Open focused on adults with food allergies. Why the shift to adults?

Ruchi Gupta: That's a great question. As I am a pediatrician, you know, over the years we've been studying, like he said, pediatric food allergy and that's where the emphasis has been, but now a lot of those kids are growing up and they're becoming adults and they're going to college and they continue to have their food allergy and then you know, at meetings with other physicians, you start hearing about how many adults seem to be developing food allergies as adults. Since we had the expertise in doing large scale prevalence studies, we thought we would modify our pediatric study for adults and really understand how many at people in the United States are affected by food allergy and what that looks like.

Erin Spain: So we really didn't have good data on how many adults?

Ruchi Gupta: No, no. We have very little data on adults with food allergy. For some reason we've all really focused on the kids.

Erin Spain: So this paper that came out did make some headlines. You found that nearly half of adults, they developed adult-onset food allergies. And was that surprising to you?

Ruchi Gupta: So surprising. I mean, we knew, like I said, you keep hearing it right? Anecdotally in clinic and you start hearing and seeing more and more adults talking about how they're developing these food allergies, but the number we found was very surprising. I mean, we really found that about half, 48 percent said they developed at least one new food allergy as an adult that they didn't have as a child. So those numbers were a little astonishing. Additionally, about one in four adults said they developed an allergy as an adult and never had a food allergy as a child. So that's, that's a lot of adults developing new allergies.

Erin Spain: And the allergies are similar to what we see in children. There's milk, peanuts, tree nuts, fin fish, egg, wheat, soy and sesame. Those are among the most common. But for some reason shellfish is at the top of the list for adults. Do we know why that is?

Ruchi Gupta: That is such a good question. I think my favorite thing about doing research is once you do a study, it opens up like 100 more that you can do and answer new questions. You're absolutely right, the top eight, we used to call it, now we call it the top nine because sesame is becoming the ninth most common allergen. Those are the same in kids and adults, but the adults have a very different order with shellfish being way beyond other foods. I think 2.9% of adults reported having a shellfish allergy. It was the most common allergen in adults by far because after that it was milk and peanut around 1.8% - 1.9%. What is it about shellfish? I've heard from so many adults "Oh my gosh, I love shellfish and I can't eat them anymore" and that is really hard for a lot of people. I think we now need to explore what is it about the proteins and shellfish and what's so unique about the specific food that is causing so much adult-onset allergy?

Erin Spain: Well, the interesting thing about this study is it was a survey. It's a survey you said that you've used for children before and it's self-reported. So people, you know say, well I think I have a food allergy or I have a food allergy. Well, tell me about that because 20% of the adults reported having a food allergy, but you determined that it was only actually half of them that seem to have a real allergy. It was more like a sensitivity from how they reported that they reacted to the food. Tell me about that.

Ruchi Gupta: Yeah. I really appreciate you asking this question because I think this has been one of the most confusing questions that's come up in the media and how people take it. So, like you said it's a survey. So people were asked, adults were asked do you have a food allergy? Then if they said yes, it went into what food allergies. So it would ask specifically. So say you said you have peanut milk and wheat. All right. Then it would take you through each food, it would say "For peanut allergy, what are your most severe symptoms that you've had?" And then you would list them and you could write in or you could choose from the list. And then it would ask you things about diagnosis and about emergency department use and about epinephrine use, right? So it asks you a series of question, then it would go into milk and would ask you the same series of questions and then it would go into wheat. So you had to be specific for each food. Now what we did with that data, because there are so many food related conditions, right? You can have so many different things that looked like a food allergy but may not be. So what we did is we tried to do our best. We had an expert panel go through and try to clean the data so that if there were things that may be something else. So say said you have a milk allergy, but you said you just get stomach cramps and some diarrhea. Okay. Then we would say, well, we're not completely sure that's a food allergy that might be lactose intolerance. So we would put it aside. Okay. So when people say they were wrong, that's not true. So let's go back to food allergies. The problem is that food allergies can impact any organ system, right, so you can have GI symptoms. In fact, it's one of the most common ones. Vomiting is one of the most common things that happen as an allergic reaction. You can have skin symptoms so you can get hives, you can have oral symptoms, you can get tightening of the throat and tingling, swelling of your mouth. You can have respiratory symptoms, you can have trouble breathing, wheezing, tightness in the chest. You can even have cardiovascular, right? The drop in blood pressure. The problem with food allergies is you can have these mild symptoms or you can have them progressed to severe symptoms with the breathing difficulty and tightening of the throat and that can be life threatening. When people report only GI symptoms - we take them out. Or they only report oral symptoms because sometimes you can have something called oral allergy syndrome where you're actually allergic to the pollen. So if you eat a fruit and you only get tingling and a little swelling and itching in your mouth, that's not a food allergy. But those could also be symptoms of a food allergy. So long story to tell you that what we really did was try to take a people who had symptoms that could look like an intolerance or oral allergy syndrome and take them out and that was about half of the people. So whether they have a true food allergy, we are not sure. Whether they have an intolerance, we're not sure. But, what it told us was that can you believe that one in five adults think that they have a food allergy and do potentially have some food related condition. That's a huge number.

Erin Spain: And it underscores the importance of getting that diagnosis and going into your doctor and really determining is this a food allergy?

Ruchi Gupta: And that was our goal by saying, look, there's one in five, but then of the convincing there's only one in 20 that are getting diagnosed. I understand this as an adult, you know, a lot of times what happens is you eat a food, you have a negative reaction, and you're like, well I just can't eat that food and you don't necessarily think, oh, let me go get it checked out by a doctor and I want this to help people think, let me go get it checked out by a doctor. Because avoiding foods in your diet is so hard, right? Trying to take out milk from everything you eat. I think for me the goal was, you know, let's try to figure out what all these food related conditions are so that you're not having to avoid a food unnecessarily and if it is a true food allergy, you need to know how to manage it because that can be life threatening and you need to know what type of reactions can happen and you need to carry your epinephrine with you.

Erin Spain: You touched on it a little bit with the shellfish. What is it about the shellfish, the protein? What are some of the hypothesis out there about why more kids and adults are developing food allergies? I know there's some theories. You're one of the experts. What do you say?

Ruchi Gupta: I know, and this is what's so interesting because we all know that genetics plays a role, right? But we would not have this epidemic and this huge increase if it was just genetics. So we need to better understand what is it in the environmental component that has changed over pretty much a generation that has caused this incredible increase. So some theories are, of course, the hygiene hypothesis, right? Like, are we becoming too clean?

Erin Spain: The hand sanitizers the soap?

Ruchi Gupta: Right. It could very well be because our bodies are not exposed to things that are not fighting things they should. They're fighting things they shouldn't. There's a couple of other really interesting hypotheses that are somewhat related. The microbiome, you've probably heard that that's really hot right now. What is it about our gut bacteria and how much of a role does that play and what are we doing to it? You know, the whole idea of getting antibiotics early in life and that first year all the antibiotics infants are getting or mothers are getting during pregnancy, other hygiene related things. You know, C-section births are up and so they're not going through the normal vaginal canal and then they're not getting that natural bacteria. Is that hurting them? Is that part of that whole hygiene piece and the microbiome that is in their gut and how do we eat, what are we eating these days? You know, are we eating locally grown food like before? No. Are eating from all over the world. What kind of pesticides are used? You know, the ideas of GMOs. There are all these question marks that we haven't fully understood yet.

Erin Spain: You're interested in looking into those?

Ruchi Gupta: Yeah, I mean, you have to. I would love to better understand what these factors are. Chances are they're not one factor. We're not going to say, oh, it's all about this. It's going to be a group of factors and how our lifestyles have changed. The one big breakthrough that's happened is there was a large study done in London called the LEAP Study and they found that if you feed infants, high risk infants, peanut products early in life, that you may be able to prevent peanut allergy. So that exposure through the gut early could be preventive. This was a really big breakthrough because for the first time we have a way to potentially prevent it. Because before that we told pediatricians to tell families to avoid peanut products until age three, which is what I did with my daughter and she has a peanut allergy. It was a very, very big finding to think that, okay, maybe by waiting we may be hurting.

Erin Spain: Now parents are giving those babies in the first six to 12 months, a little bit of peanut butter.

Ruchi Gupta: They should. They should absolutely. I mean, I think that is a very important finding and all parents of infants should initiate peanut products watered down peanut butter. Early in life, by that, you know, not the first food, but in that first group of foods, like around six months for sure.

Erin Spain: You're a pediatrician as you mentioned and this is your focus - children and allergies. How did you start down this path? You mentioned that your daughter has a peanut allergy.

Ruchi Gupta: So it's an interesting story because I am a pediatrician and I came to Northwestern and Lurie Children's 14 years ago to really study asthma disparities and to work with one of the leaders in the field that was here at that time and I met a family with two young children with very severe food allergies. Been to the ER and hospitalized and they really wanted research to be done in this area. I was junior faculty, "Hey, you want to come in, you want to work on this?" I knew very little about food allergies back then, but what I found was compared to asthma, which I had been studying, there was a huge hole. We didn't even know how many, as you know, we talked about. We didn't know how many kids had it, how many adults had it. We didn't know the basic prevalence or types of foods people were allergic to or what kinds of symptoms. All that data was not in the literature. I was trained in health services research and had my MPH and I was fresh and ready to start. I thought, you know, this may be an area that I could make a difference and have an impact because so little is known. So that's how I started. As I was studying it, three years into it, I believe, my son who loves peanut butter and jelly sandwiches, was playing with my daughter and touched her, I guess all over her face because she just broke out in hives.

Erin Spain: And you knew what it was immediately?

Ruchi Gupta: Oh yeah. I'm like, wow, you know, what kind of gift is this? It's really had such an amazing influence on my life and my career because there is a big difference just studying a condition and then living with a condition and all the things I go through every day in my life with her really do help influence the research. By having her I know so many others with food allergy and then these support groups and listening to what their needs are. Right? Listening to that patient and that whole patient centeredness. It just really brings that home because they know what they need. We as researchers need to listen to them and answer their questions. So, it's been a blessing in some ways. But yeah, very difficult.

Erin Spain: How old is your daughter now?

Ruchi Gupta: She's 12.

Erin Spain: She's still working through the peanut allergy? Because I know at some point a lot of people outgrow it.

Ruchi Gupta: She is working through it. Only about 10 to 20 percent outgrow peanut allergy. She's got peanut and tree nuts and she used to have an egg which she has outgrown. It's a challenge every day because, you know, we don't have a severity spectrum for food allergies, which I think a lot of parents, it really affects their life because if you don't know my child is mild or moderate. You know, people ask you, "Oh, how severe is it?" and we have nothing to tell them and so everyone's severe, right? Everyone could have a life threatening reaction. It's a lot of anxiety and fear for families because food is a part of everything kids do. Even adults.

Erin Spain: You're doing so much to bring knowledge into the scientific community and build the literature. In 2011, you led a study that, found that eight percent of kids in the US have at least one food allergy. This was new information as you said, we didn't know before, and 40 percent of those kids had experienced a life threatening reaction already in their lives. How important was this when you were able to actually put some numbers out there?

Ruchi Gupta: It was really incredible to see what happened after that because after that study, people had numbers that they could hold onto and tell schools and see it in their classrooms. You know, 8% is about two in every classroom. It's about one in 13 kids. When you picture it like that, you're like, oh yeah, that's true. You know, there are about two kids in the class that have a food allergy and you realize how realistic this is and how prevalent. By being able to list the foods and talk about the reactions I think it made more sense and it increased awareness and people started to get it and we actually repeated that study that was published in pediatrics again in December of 2018. What was interesting, the numbers are pretty comparable, but we asked this time about emergency department visits and one interesting thing we found was of kids with food allergy, about 1 in 5 go to the emergency department every year for their food related reaction.

Erin Spain: So these are severe reactions? Life threatening reactions?

Ruchi Gupta: Yeah. They are having them and so people would say, "Okay, you have a food allergy, but how much does it impact your life?" So, for the first time we were able to quantitate that and say, you know, 1 in 5 are going every year. It's a big deal. It's something that we have to take seriously and help protect these kids.

Erin Spain: And what is it, about 150 children, they actually die from the reaction and that's something that you were trying so hard to prevent through education and awareness.

Ruchi Gupta: Every time that happens, like all of our hearts are broken and we want to prevent that from happening so badly and not only the deaths but even the severe reactions because they throw you off course. You know, when you have one of those close calls, it messes you up. It's hard to then go out to eat and do normal things. But what's so great, I feel like, you know, in the 14 years I've been in this field, I've never seen a field change so much. So the amount of research that's happening now, we actually have treatments that will be coming out this year.

Erin Spain: Wow.

Ruchi Gupta: Yeah, so a lot of the researchers at Lurie Children's are working on them. There is oral immunotherapy. Eating small amounts and increasing the dose and that's going to hopefully be out later this year. It's already in phase filed five clinical trials. It feels very, very likely that it'll be on the market. There's a patch epicutaneous immunotherapy for peanut that's coming out and then these companies are working on the next set of foods, the next most common foods. There's a couple other treatments that I've heard of and that are in different phases of trials. So I feel like in the next five to 10 years we'll have great treatments for food allergy. The other great thing that I've seen change over time in this 14 year period, as the awareness has been picked up, schools and Chicago Public Schools where one of the first to join us building policies, having stock epinephrine in case of an emergency. Unfortunately, this all was sparked by, as you said, a young child dying in school after an anaphylactic reaction and there was no epinephrine. After that CPS said, we're not going to ever let this happen again. They passed a law to have stock epinephrine in every CPS school. And then all through the country, I think, every state now has a law or a policy around stock epinephrine in school. To see policies developed, to see the community coming together to protect kids and adults with food allergy so quickly is so inspiring.

Erin Spain: You said kids are sometimes the biggest advocates, classmates, they want to help protect their friends.

Ruchi Gupta: Yes, and to that, you know, we do three areas of research that epidemiology, that we've talked about, we do a lot of the clinical care, kind of that early introduction stuff that we talked about. The third big bucket we have is community. We work very closely with the schools and we've actually developed videos that are free on our website and for schools to use around how to teach a classroom about food allergies and how to have your peers be supportive. What we found is that is the number one thing to protect these kids - is if they have that peer support and not the bullying. Bullying is also very common, but if we can take it to developing more peer understanding and peer support and it could change these kids' lives.

Erin Spain: We'll make sure to put links to those videos on the podcast website so people can look them up and share them. (Watch Gupta's food allergy peer-to-peer educational videos.)

Ruchi Gupta: That would be great.

Erin Spain: Well this is fascinating. The past 14 years, as you mentioned, so much has changed, but it sounds like we are now at a point where there's going to be some real treatments and we're really looking forward to see what's coming up.

Ruchi Gupta: Thank you. Yeah, I am too. You know, I have a little cartoon on my wall at work and it is what I hope to see. It's an adult talking to a kid and the adult is saying, "You know, in my day there were no food allergies", because this is what you hear all the time. Then that kid grows up and as an adult talking to a kid and saying, "You know, in my day there were food allergies". So hopefully that's where we're headed and hopefully I can help be a part of that.

Erin Spain: Well, thank you so much Dr. Ruchi Gupta for coming and sharing your research with us today.

Ruchi Gupta: My pleasure. Thank you.

Erin Spain: A note for physicians who listen to this program, you can now claim continuing medical education credit just by listening to this podcast. Go to our website and search for "CME" for more details.

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Physicians who listen to this podcast may claim continuing medical education credit after listening to an episode of this program.

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At the conclusion of this activity, participants will be able to:

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Credit Designation Statement

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Disclosure Statement

Ruchi Gupta, MD, MPH, has received grant or research support from Food Allergy Research and Education, Genentech, Inc, Melchiorre Family Foundation, Sunshine Charitable Foundation, Walder Foundation, UnitedHealth Group and Thermo Fisher Scientific. Gupta also serves on advisory committees or review panels for Genentech, Inc., Novartis AG, Food Allergy Research and Education, Allergenis, Aimmune Therapeutics and is owner of YoBee Care, Inc. Course director and content reviewer, Robert Rosa, MD, has nothing to disclose. Planning committee member, Erin Spain, has nothing to disclose. Feinberg School of Medicine's CME Leadership and Staff have nothing to disclose: Clara J. Schroedl, MD, Medical Director of CME, Sheryl Corey, Manager of CME, Allison McCollum, Senior Program Coordinator, Katie Daley, Senior Program Coordinator, Michael John Rooney, Senior RSS Coordinator, and Rhea Alexis Banks, Administrative Assistant 2. All the relevant financial relationships for these individuals have been mitigated.

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