Lessons from America’s peanut allergy flip flop

Transcript

Part I

MEGHNA CHAKRABARTI: Before the year 2000, less than 1% of the U.S. adult population suffered from peanut allergies, but in the late ’90s and early 2000s, that seemed to change. More stories started popping up about peanut allergies being on the rise. For example, here’s a clip from 1998.

NEWS BRIEF: NBC News in depth tonight. New fears about an old childhood favorite. Peanuts.

The Department of Transportation will now actually require major airlines to provide peanut-free buffer zones on request.

Peanut products are in more foods than ever used as oils and fillers exposing them more often than the past.

They’re being introduced into children’s diets at a younger and younger age. Perhaps before their immune system is fully ready to handle peanuts.

CHAKRABARTI: That clip courtesy of the Vanderbilt News Archive. So the American Academy of Pediatrics decided to do something on August 2nd, 2000, the AP issued a policy statement titled Hypoallergenic Infant Formulas. Now let’s first note a couple of things just from that title.

The policy paper was about infant formula. Second, it was also about a subset of infants who showed adverse reactions to some proteins found within infant formula. These infants were truly at risk, so it was really a paper about encouraging breastfeeding and helping infants and mothers who had protein sensitivities and who could not breastfeed.

This policy paper was not about avoiding peanut allergies. In fact, the word peanut occurs only seven times in the entire document, and the most specific guidance the document provides about peanuts is this one sentence, and it goes like this:

“Solid foods should not be introduced into the diet of high-risk infants until six months of age, with dairy products delayed until one year. Eggs until two years and peanuts, nuts and fish until three years of age.”

That’s it. Note the keywords high risk infants. And yet somehow, that guidance morphed into something like gospel with pediatricians, public health officials and terrified parents believing instead that no infant should ever touch a peanut until they were well into toddlerhood.

Now this should have worked. As I said, peanut allergies were seemingly on the rise before 2000, but instead of reducing them by 2008, rates of childhood peanut allergy in the U.S. more than tripled to the point where almost every school room cafeteria and yes, airplanes had some kind of warning or restriction on nuts.

What had been rare suddenly seemed not just common, but ubiquitous across the United States.

This is the information and parenting environment that Lisa Rutter was raising her son in when she first got married. Lisa’s favorite foods, or one of them at least, was peanuts. Peanut butter was a staple in the house. At her wedding, the small party favors she handed to guests included bags of peanut M&M’s.

So Lisa never thought she’d have to live without them until her first son Evan was born.

LISA RUTTER: We would still eat them around him. I didn’t know at the time, but just like the oils on my fingers would make his eyes swell up. He would have bad reactions on his face. He had terrible colic. He would be screaming all day long.

My husband would come in from work, and I would be like, okay, your turn. And then eventually it just kept getting worse.

CHAKRABARTI: Evan’s pediatrician diagnosed him with a severe peanut allergy. Bottom line, he could suffer anaphylactic shock and die from just one peanut exposure.

RUTTER: All of a sudden, you’re like, oh my gosh, all this stuff that I have in my house, you’re like, you have to go through the whole pantry, throw out everything.

You have to start reading every single label. Some people call manufacturers just to make sure that they have different lines. Everybody’s comfort level is different, but it is this emotional rollercoaster. Even around family and friends, you’re walking into Thanksgiving now with families.

It’s just a whole new world, and it is so hard.

CHAKRABARTI: Peanuts came to dominate Evan’s every stage of life. Lisa had to ask her school to establish nut-free areas and parents to avoid bringing nuts to bake sales. She had to check the menu at every restaurant. And always keep a vital EpiPen handy. Now Evan’s in high school, meeting more people and going to parties, and Lisa says she has to get used to the fact that he is more independent.

This summer, Evan flew for the first time alone to visit his girlfriend, and soon he’ll be off to college.

RUTTER: He just needs to be vocal and not embarrassed. Because those are the stories. Kids accidentally ingest something, they’re at a party, they feel embarrassed, they leave, go off alone. I try to tell him absolutely never, ever do that.

I just need him to be confident.

CHAKRABARTI: So while all this was happening, scientists began quietly questioning the AAP’s 2000 guidance. Research began popping up that avoiding peanuts altogether could be making childhood allergies worse. Then in 2017, the American Academy of Pediatrics made a huge 180. The Academy recommended introducing peanuts in small doses before your baby’s first birthday.

Lisa Rutter saw the news after her daughter was born.

RUTTER: I would go over to the local hospital, and I would sit in the parking lot, and I would feed her Reese’s Pieces or anything like that and just sit there and watch her, like a hawk. Because I wouldn’t allow it in my house, even though they were saying, don’t avoid it.

So I did that with her at a young age and we were good.

CHAKRABARTI: Now, Lisa believes that no matter what, Evan would have gotten some kind of peanut allergy, even if she tried introducing it to him more often as a baby. But she says a lot of moms she knows are questioning their decision making and there are still millions of people living with food and specifically peanut allergies now, which Lisa feels they have become stigmatized.

RUTTER: This was my first child and I’m sending them off to class without me. You already have so much to worry, but then you add that. I just wish that some other moms could be more supportive and compassionate and understand, you might not agree with how they’re so worried. And yes, their kid might be totally fine, and the mom is totally overreacting, but who cares?

We all need to support each other, and we need to just keep kids safe no matter what.

CHAKRABARTI: New research out this year finds that following that AAP guidance change, peanut allergies amongst young people are down in the United States. So what are the lessons that the American Public Health System should learn here?

Are there lessons about how to avoid being caught up in say, emotions and trends that could end up hurting more than they help? That’s what we’re gonna talk about today, and we begin with Dr. Robert Wood. He’s Chief of Pediatric Allergy and Immunology at Johns Hopkins Children’s Center. And Dr. Wood, welcome to On Point.

ROBERT WOOD: Thanks very much. It’s a pleasure to be here.

CHAKRABARTI: I should also note that you’re author of Food Allergies for Dummies. But Dr. Wood, I want to first make it clear to both you and all of our listeners that we’re not questioning that people have peanut allergies and sometimes they can be severe and even life threatening.

We’re not even questioning the rise of food allergies in general in the United States. These are all real issues that we need to understand better. And in fact, because of that is why we want to understand what the dynamics are around guidance. How that guidance may have or haven’t had an impact on what seems to be a dramatic drop in peanut allergies in this country.

I just wanted people to be sure that we are not doing what Lisa rightly noted, which is potentially stigmatizing folks.

WOOD: Of course.

CHAKRABARTI: Yeah. So first and foremost. If we could, doctor, I would actually like to go back and start with that 2000 policy statement from the American Academy of Pediatrics. I don’t know if you have any knowledge or recall, but this was a statement about infant formula in general.

Was that kind of just a normal thing for AAP to put out back then.

WOOD: It was, and I think that some confusion that came from it is that there was some information on infant formulas that was valid, based on good scientific studies. And then there was some hypotheses and other recommendations that were made really without any good evidence.

More just a feeling that we had taking care of babies that this might be the right thing to do. Now we need to get into a little bit of actually how much damage that did. It was clearly a wrong recommendation, but I’m gonna start off the conversation a little bit saying.

That the rise in food allergy is not just peanut, it’s actually all foods. That this one guidance may or may not have any bearing on the increasing prevalence of peanut allergy. And the new guideline may or may not have any change in the prevalence of current peanut allergy. So there’s a lot of still unanswered questions and we need to be careful not to make a jump to a cause and effect.

This one guidance may or may not have any bearing on the increasing prevalence of peanut allergy. And the new guideline may or may not have any change in the prevalence of current peanut allergy.

Robert Wood

We know that happened and now we know this happened. So the rate of peanut allergy is down.

CHAKRABARTI: So we’ll over the course of this hour, we will investigate the strength of that correlation and whether we can, I hear you saying we cannot extract any causative conclusions. I promise we will do that.

But I still want to spend some time with this early guidance. Because from my understanding, it is from this guidance that somehow, and this we have to admit is true. I went through this with my pediatrician for both of my kids. Somehow you end up with parents hearing advice that they should avoid all peanut exposure for your kids.

No matter if they have allergy sensitivities or protein sensitivities or not, until they were quite a bit older. That did happen. Did it not, Dr. Wood?

WOOD: Absolutely. Absolutely.

CHAKRABARTI: And so to that point, we have 30 seconds before our first break here. I also just wanna establish factually, again, when the 2000 guidance was put out, it was about really supporting women breastfeeding and helping children who already had evidence of some kind of protein allergy. Is that correct?

WOOD: Yes. Yep, that’s correct.

CHAKRABARTI: Okay. But that’s important to understand, right? Because these are kids who were indeed at threat of  growing up with even worse allergies.

Part II

CHAKRABARTI: Dr. Wood, overall, as I read this document, it really addresses something important, which is that there were already, or there are already some infants that have like acute protein sensitivities.

And that means that certain formulas, certain infant formulas, they cannot consume even as tiny babies. And it’s better for mothers who can, to breastfeed those children, those infants. But in that case, the guidance does say that the mother specifically should avoid trying to eat fishes or tree nuts, et cetera, for concern that those proteins could end up in breast milk.

I read a lot of this initial guidance as being focused on helping mothers with their protein sensitive infants. How do you think that one part at the end of the document, the one part, which says, for infants who are already at risk, peanut introduction should be delayed until three years of age.

How did that, from your understanding, turn into parents commonly believing that all kids shouldn’t be having peanuts for many years.

WOOD: Yeah, so it’s a great question and a topic we talk about with our patients all the time. And I think part of it is, you know, how the information gets translated and it gets translated mostly through pediatricians.

And pediatricians really do rely appropriately on guidelines from a great organization like the AAP to make recommendations to their patients. So it’s really a shame, if any misinformation at all ever makes it into one of these guidelines, that then get translated through pediatricians and through the news media as well.

If any misinformation at all ever makes it into one of these guidelines, that then get translated through pediatricians and through the news media.

Robert Wood

But at that point in time, I think much more so than now when there’s a wealth of information that can be gained elsewhere, that the pediatricians did pick up on this, in generally saying avoiding these major food allergens, especially peanut would be the right thing to do.

CHAKRABARTI: Okay. Now, I have to say, pediatricians are incredibly hardworking people. I am not, nothing in this hour is insinuating ill intent on their behalf. When you have only a small period of time in the office with these tiny babies and their very nervous new parents, you got to get a lot of information across.

So I can understand how some things which were highly specific might be generalized, just to be sure you get the information to families. But you had said a little bit earlier that some of the guidance wasn’t necessarily based on actual data or research. Clarify that for me?

WOOD: Yeah. The guidance was really based on a hypothesis that the infant, especially those infants who may be more prone to allergy, would be benefited if we didn’t subject their immune system to exposure to these allergens like peanuts too early in life.

But it was really based on a hypothesis and not any real data. There might have been some data in some mice, some data, some other animal models, but it was premature in retrospect, in terms of making any firm guidelines. Because there were not the kind of epidemiologic studies that was published a couple weeks ago, saying that there’s actually evidence to say that this avoidance would make a difference.

And certainly, no thought that it would do harm.

CHAKRABARTI: Do we know where the hypothesis emerged from of avoidance being protective in children?

WOOD: Part of it actually is within that infant formula piece, which was saying, let’s use hypoallergenic formulas. And I can tell you also, that guidance has mostly gone away.

If a baby needs to be on a hypoallergenic formula for the allergies that they’re showing, that is one thing, but as a sort of a reason to do it for prevention, turned out to be really mostly misguided as well.

CHAKRABARTI: Is this common though? In medical organizations that issue guidance to issue guidance based on a hypothesis.

WOOD: I think it is still common, but the criteria that are now required to issue something that we would call a guideline or a position statement from a major organization have changed dramatically. And one of the nice things that’s happened in the 25 years since that guidance is really using something referred to generally as evidence-based medicine.

Where you do not make a statement and where you actually grade. So there’s something called literally GRADE criteria for any basis to make a medical recommendation. So it’s still happening. There’s no doubt it’s still happening. There are some studies that really turn out in the long run to be incorrect because of some issue with the way the study was done.

But I think the risk of that happening is far less now, because of some very smart people who have really made it very clear that without having the specific criteria that would make a guidance, guideline, position statement valid, it should not just be said at all.

CHAKRABARTI: And so this is an important distinction, right?

Because an evidence-base changes all the time, right? It evolves with the research and studies that takes place over time. And that is distinctly different though, from issuing a guidance based on a hypothesis for which there is no evidence base. There was a cultural basis though.

I understand that before 2000, for example, in the United Kingdom, the UK had actually introduced two years prior an almost identical guidance that high-risk infants should basically be completely avoiding peanuts for quite some time. And so the AAP’s guidance came a little bit after that.

It wasn’t just the first on planet Earth. But I also wonder, again, I’m going to really ask you to draw on your experience, as a pediatric allergy expert. That when we start getting these news reports in the late ’90s and early 2000s about a growth in peanut allergies. I want to really interrogate the media’s role here as well, but at that time, as far as I understand, we didn’t know why that was happening.

And so I imagine that it’s very hard for pediatricians who have worried parents coming in, saying, I actually don’t know what to tell you to do, because we don’t know why this peanut allergy, peanut allergies are growing.

WOOD: True. And there was a new guidance that was published in 2008, and the 2008 guideline says, We don’t know what we’re doing, so we can’t give you specific advice in either direction.

CHAKRABARTI: Okay. But so I guess it seems to me though, that the American Academy of Pediatrics, was just actually trying to help, right? Give doctors something to say if your child is high risk, here’s what we think you should do.

WOOD: Yeah. But in 2008 it was, we don’t know what you should do, so feed your babies normally.

And then thankfully, the most important thing of this is that there very smart people who questioned this hypothesis. And that the right study got done, which is a very important study, maybe the most important study in the world of food allergy in the last 25 years called the LEAP Study.

Maybe the most important study in the world of food allergy in the last 25 years called the LEAP Study.

Robert Wood

And the LEAP study clearly showed that especially if you take babies at high risk for developing food allergy, that early introduction was highly beneficial, reduced the development of peanut allergy by about 85%. So that was a key piece, and that led to the next guidelines that we’ll talk about in a moment.

I’m sure. Of, let’s do this 180 change and start talking about early introduction rather than this ridiculous delay.

CHAKRABARTI: Wait, say that again? The study, there was one study that found that was it introduction before age three, reduced allergies by 85%. I want to be sure I heard that right.

WOOD: So this was reduction in the first year of life.

CHAKRABARTI: First year of life. Okay.

WOOD: And it was taking babies that had either severe eczema and or egg allergy, and then actually doing the study, which is tricky business, but randomizing the babies to either get regular peanut introduction, eating peanuts at least three times a week, or avoiding peanut till the age of five.

And that study showed that the early introduction did reduce the development of peanut allergy by over 80%.

CHAKRABARTI: Wow. Okay. Now —

WOOD: And that was a game changer. That’s what led to now we’re gonna have new guidelines and whether these new guidelines are working or not is still an open issue.

But that was a incredibly important study. Took this field from a hypothesis to real data.

CHAKRABARTI: Got it.

WOOD: And the data wasn’t just maybe. It was, Oh my gosh this is life changing. It really should influence pediatric practice, pediatric allergy practice, the day the study was published.

CHAKRABARTI: And at the same time though, you’re saying this is 2008 and thereafter there’s a study from Mount Sinai. That found that between 1997 and 2008, the rate of childhood peanut allergies more than tripled in the United States. Something was happening.

WOOD: Something was happening and a real question that we may not have time to get into today is whether that had anything to do with the peanut avoidance.

Because it may not have.

CHAKRABARTI: So let’s actually bring in Dr. David Hill now because he is a pediatric allergist at the Children’s Hospital of Philadelphia and an assistant professor of pediatrics at the University of Pennsylvania, and he is the principal investigator of a study that I mentioned.

At the top of the show that came out this year, it was published in the Journal of the American Academy of Pediatrics, and it found that there is a 43% drop in peanut allergies in young children since the American Academy of Pediatrics updated its peanut allergy guidance in 2017. Dr. David Hill, welcome to you.

DAVID HILL: Hi, Meghna. Thanks for having me.

CHAKRABARTI: So let’s get straight to this. Is this causal or is it just a correlation?

HILL: So this would be non-causal. This is a correlation or an association. So what this study essentially did was ask, What are the rates of new food allergy immediately before these, this 180 recommendation in 2015 and what are the rates immediately after?

And if we compare those two groups, which are otherwise similar, we can get a sense of what direction are new onset food allergy rates going in.

CHAKRABARTI: And the direction is down.

HILL: And the direction is down. That’s right. So we found that there was a 43% reduction in peanut allergy prevalence and a 36% reduction in all cause anaphylactic food allergy.

CHAKRABARTI: Okay. So what do you think the significance is of this? If it’s just correlative and we can’t say specifically that after 2017, because of this guidance. And the key thing is, because of this guidance, maybe food allergies, specifically peanut allergies, have dropped dramatically in the U.S.

HILL: So I think any, rigorous public health initiative has three core parts, and the first core part is the gold standard randomized control trial, that showed that early peanut introduction reduced new onset peanut allergy, right? That’s the LEAP study that Dr. Wood was mentioning in 2015. The second pillar are the clear specific public health guidelines that initially came out in 2015 and then we’re revised in 2017, subsequently revised again in 2021. And then the third pillar is asking, okay, we did this gold standard trial, we made these recommendations publicly.

Has there been any effect in the general population? Now with those large population studies, it’s not possible to get a causality, because we already have causality. That was the LEAP trial, that actually showed that early peanut introduction worked. What we’re asking here is, are we seeing the intended effect?

And in this particular case, in our study group, we are.

CHAKRABARTI: So can one then make a reverse conclusion about 2000 and say that there is a strong or any kind of correlation between the 2000 guidance and an increase in peanut allergies between 2000 and 2008?

HILL: I think an important aspect of this conversation that hasn’t come up yet is that there’s actually multiple factors that influence allergy risk generally, and food allergy risk specifically. So there are other environmental factors that increase that risk. I’m talking about things like antibiotic exposure, has been shown to influence allergy risk, broadly speaking. And we think that could be with modifications to the microbes that live on inside of our bodies.

There’s actually multiple factors that influence allergy risk generally, and food allergy risk specifically.

David Hill

So it’s always very hard to say that any specific thing led to a particular public health outcome. In this case, the way we tried to be as specific as possible is really looking at that time period immediately before the recommendations and the time period immediately after. And what we can say is that in the 120,000 kids that we studied, new onset food allergy rates went down. And then I think it’s a broader question for the field to confirm these findings, look in other populations, et cetera, et cetera, to understand the extent to which we think that this public health recommendation was causal in that effect.

In the 120,000 kids that we studied, new onset food allergy rates went down.

David Hill

CHAKRABARTI: Okay. Forgive me for being dense, Dr. Hill. Okay. And Dr. Wood, as well. Forgive me for being dense, but I hear both of you saying that we did have a gold standard study that showed that at least for high-risk infants, that earlier introduction of peanuts was causally related to reducing and dramatically how much the prevalence of peanut allergies in those children.

That is a causal relationship, but we refuse or are unable to extrapolate from that to the larger population study, essentially that you did, Dr. Hill, I don’t even hear you saying that you’re willing to say that it’s partially causal, as in finding that 43% drop in peanut allergies across the country.

HILL: I think sometimes, and rightfully, scientists and doctors can be very specific with their language, and that is important. That’s something that we’ve learned, is critical when we’re messaging to the general public. And the truth is with the study that we performed, we didn’t look and see which kids did early peanut introduction and which ones didn’t.

We looked at all the kids, we said of these 120,000 kids, some of which did early introduction and stuck with it, some of which did early introduction and might have not continued it, and some of which didn’t do early introduction, what happened in the food allergy rates? And that’s why we can’t say that it’s causal.

But I will also say that in some ways the LEAP study established causality. And so the purpose of this study was not to reproduce the findings of the LEAP study. It was to ask, okay, so we made this big recommendation in 2015 and 2017, what has the effect been or what have food allergy rates done essentially in the period after that recommendation?

Part III

WOOD: I think the problem that we want to avoid here is drawing causal conclusions, this would be not that different than the 2000 guidelines that were wrong. Because we don’t have the data. This was not a U.S. wide study. It was geographically limited. We didn’t know, as Dr. Hill appropriately said, that these babies actually ate peanut early. In fact, they might not have eaten peanut, which is why they didn’t show up for the peanut allergy yet.

There’s lots of unknowns when you do a chart review kind of study. There are studies from Australia where they did skin testing and food challenges. The gold standard testing to know if someone’s allergic that showed the rate of peanut allergy went up after the guidelines. So we need to be very careful.

And the other thing that I just want to make sure the audience knows, is that the epidemic of pediatric food allergy is not just peanut. In fact, other food allergies have increased. Similarly, Dr. Hill’s amazing study actually showed that egg allergy is the most common food allergy in infants and toddlers.

All of these rose at the same time. And I’ll give one other statistic that’s just shocking to me. Is that back in 1995, I wrote an article that said that 80% of babies with peanut allergy were allergic to one food, 20% were allergic to more than one food. And now we have data saying that 88% people with food allergy, allergic to multiple foods.

So this has been an epidemic, no doubt about it. But it’s an epidemic that is absolutely not specific to peanut. And where these different guidelines probably had some influence on the increasing rate of peanut allergy. But we’re also seeing that in the community, guidelines for introducing peanut early are not generally being provided to their patients.

Dr. Hill’s study had a very unique set of pediatric practices that are probably a little bit more on the advanced side of pediatric care. So that might have made a difference in the results that they showed. But when I survey my patients, were you told to introduce peanut early? The majority of them say no.

In fact, they can show me handouts their pediatrician gave them, saying do not introduce peanut until 12 months of age. So it’s not like there’s been a sea change in advice from pediatricians. And it’s not like this is a unique problem to peanut allergy. And we think that there are, I’m saying we, I’m speaking for myself. But I think most people studying this field think that there are many reasons for this epidemic of food allergy.

And to focus too much attention on this one guideline, which we all agree was misled, inappropriate is not telling the even close to the full story.

CHAKRABARTI: Dr. Hill, would you like to respond to that?

HILL: Oh, only to reinforce what Dr. Wood said, in that I think the key here is that we are thoughtful and effective communicators.

That early allergen introduction is safe and effective, and that we try to reinforce that with families and with pediatricians to try to increase adherence to these new recommendations.

CHAKRABARTI: Okay. So I have to say I appreciate the broader context and the encouragement to step back from any sort of facile conclusions here about peanut allergies in particular.

So then that makes me want to ask both of you. What in the heck is actually going on in the United States? And here’s my basis for that question. Both of you mentioned the LEAP study. Okay. And that LEAP study, for people who don’t know, was actually performed by Dr. Gideon Lack. He is a pediatric allergist and immunologist in London, England.

And what’s fascinating, this story is pretty well known amongst people in the immunology world. And it’s been reported a couple of times in the media, but it’s worth repeating here, that Dr. Lack in the year 2000 was giving a lecture in Israel on allergies, and he asked, there was like a couple hundred pediatricians in the audience. And he asked them, how many of you are seeing kids with a peanut allergy? And only one or two of the Israeli pediatricians raise their hand.

He goes back to London, asks the same question in front of a group of British pediatricians, and nearly every pediatrician in the UK raises their hand to the exact same question about are they seeing kids with peanut allergy? There seems to be, in comparison to the rest of the world, a particular problem in the UK and the U.S.

I don’t think, and correct me if I’m wrong, but I don’t think we see anywhere near as high a rate of peanut allergies in any other country other than at least those two, Dr. Hill, first of all, is that right? And second of all, then what are the other factors in the U.S. and the UK that are unique and different from the rest of the world in terms of all allergies to peanuts amongst infants?

HILL: Yeah. You’re correct in characterizing that observation as a an ‘aha’ moment. I think not only for Dr. Lack, but for the allergy and immunology community. I think it is not the case that the UK and the U.S. are isolated in elevated food allergy rates. We also see high rates of food allergy in Canada and in Australia, just to name a few.

But what really stood out was that food allergy rates or peanut allergy rates were so low in Israel. And it was suspected that’s because in Israel there’s a peanut-based snack called Bomba, which is one of the first foods that’s introduced to infants. It’s the equivalent of our Cheerios, if you will.

And that was part of the observation, and if you put that observation on top of a few decades of research showing that the gut immune system, meaning the immune system in the intestine, is actually very good at figuring out what’s harmful and what’s harmless.

This concept emerged that if we could get kids to encounter food allergens first in the gut, that would actually prevent them going on to develop food allergy.

CHAKRABARTI: It’s interesting that you say that, again, I know that we keep going of going back and forth between peanut allergy and food allergy and for the purposes of maintaining some kind of bound around which we’re talking about for listeners to understand, I’m going to focus on peanut allergies here. So you mentioned the UK, U.S., Canada, Australia. These are highly developed, quote-unquote, westernized countries. Dr. Wood, are there other aspects of, I don’t know, our food system, of people talk about the hygiene hypothesis as making children overall more allergy prone.

I still feel like there’s a big difference between those countries and most of Asia, all of Africa, where the rates just aren’t the same.

WOOD: They’re not. But let’s not focus on the U.S. being different. The U.S. is the same as all of Europe, Australia, New Zealand, Japan, and even as you monitor a country that becomes more westernized, that’s going on in cities in China right now, the rate of food allergy is skyrocketing.

This is not a U.S. issue. It’s a developed country issue, and there are a dozen or so theories as to why this dramatic increase in food allergy. And it’s not just food allergy. It’s happened with other allergic diseases. Food allergy may be the easiest to focus on. Around the world you mentioned the hygiene hypothesis, which is probably a major reason why food allergy is so much less common in very underdeveloped countries.

This is not a U.S. issue. It’s a developed country issue, and there are a dozen or so theories as to why this dramatic increase in food allergy.

Robert Wood

And the hygiene theory says very generally that the more your immune system is kept busy with other, fighting off other things. Let’s say your water’s not pure, that you encounter a parasite. There’s so many different things that may take up your immune system that the less time it’s spending worrying about those things, the more time it can spend on worrying about things like allergy.

If you look at Asian immigrants to United States or Australia or New Zealand, their rate of allergy increases dramatically once they move to a westernized country. And a few of the things that Dr. Hill mentioned in terms of use of antibiotics, other exposures that may expose babies to a richer kind of bacteria and other germs in their environment may actually help reduce the development of food allergy.

And there are probably other factors in terms of how foods are processed, in terms of specific nutrients in the diet. And the reality is that there are huge unanswered questions that go so far beyond early introduction to foods, that we need to understand before we’ll really be able to get a handle on what’s going on.

And then the holy grail here is how do you prevent food allergy? And right now, we don’t know how to do that. Because we don’t understand it well enough to actually intervene effectively, except for some very specific examples like early introduction of peanut.

CHAKRABARTI: Let me just say, Dr. Wood, I’m rightly, I am quite confused here because maybe it’s just the studies I’ve been reading are a little bit out of date.

Because you just said like Japan also has higher rates of childhood food allergies. Because over the weekend I was reading a 2018 paper that was published in Allergy, Asthma, and Immunology, that journal. And it says it found that using randomized control trials in the U.S., UK, Australia, and Japan.

They found that rates of food allergy in Japan were much lower than in those other countries, U.S., UK, Australia. But you said Japan is also high.

WOOD: It’s an example of all developed countries seeing a rise. Japan, it turns out to be different allergens. They don’t have much peanut exposure.

They don’t have much peanut allergy, but they have dramatically higher rates of fish allergy than we have in the United States. So a lot of it has to do what’s prevalent in your diet. The best studies on this have actually come from Australia. And they’re showing, rates of food allergy that are higher than anywhere else in the world, partly because they’re doing the studies to actually investigate it in a way that does things like food challenges.

It’s in general, just best to think of this as I think about it, that in developed countries around the world, food allergy has increased. There’s no evidence that this rise is actually plateauing. It may be, we hope it is. These are studies that take a while to get done and show that.

But from what I see, and what most of the data shows, the rates of food allergy around the world in developed countries continue to rise.

CHAKRABARTI: In developed countries. Okay. Dr. Hill, let me turn back to something that Dr Wood just said. Because it’s reflected in this 2018 paper that I was just referencing.

Because they also found that children of either Asian or white ancestry who were born in Western countries had increased risk of peanut allergy compared to those who were born in Asia and that ethnic Asian children born in Western countries had a fivefold higher risk of tree nut allergy as compared to Asian born Asian children.

So again, we can’t pinpoint one thing, food and the immune system. It’s complicated. But there seems to be at least one conclusion that we can draw, is that something is distinctly different in developed countries, or even as countries become more developed, that’s making people and children more allergic to common foods.

So with that in mind, what advice would you give parents today? Because we still have very scared, and understandably scared parents who, you heard at the beginning of the show, they drive to the emergency room parking lot with their tiny baby.

HILL: Yeah. I’m very empathetic —

CHAKRABARTI: Because they are so afraid that if the first time they give them a little peanut butter with their infant oatmeal that their child could die.

That is not a tenable way to raise children.

HILL: No, and those are exactly the kinds of patients that Dr. Wood and I have interactions with on a daily basis. And so we really have an opportunity to understand that impact as best we can. I do want to be careful though, because your listeners might not know that for some of the things we’ve been discussing, we’ve crossed over that line from the gold standard randomized control trial into more of the epidemiologic studies.

Which cannot be causal. They cannot identify causal relationships. And so I actually don’t want to speculate on sort of additional factors that could be at play here, until we have those randomized control studies that really show definitively that there’s a causal relationship between a particular behavior or environmental factor and food allergy outcome.

CHAKRABARTI: Point taken, but once again, we have just about a minute and a half left from you. What would you, there are parents listening right now or maybe someday parents.

HILL: So my recommendation would be as follows, and that is to essentially follow what are the 2021 guidelines. And what they say is that for most children, once developmentally appropriate, and what that means is once they’re not going to choke on the solid food, that you introduce the major allergens.

For most children, once developmentally appropriate, and what that means is once they’re not going to choke on the solid food, that you introduce the major allergens.

David Hill

For most kids, that’s somewhere between four and six months of age, but not for every kid. So you should work with your pediatrician to find the ideal timing for your child. You should introduce those major allergens. This includes peanut but as well as milk, eggs, soy, wheat. And once you have those foods in the child’s diet, you should keep them in their diet three times a week.

And what the evidence has shown, the gold standard evidence, is that by doing so, it’s both safe and it’s effective at reducing new allergy onset. So you’re going to reduce the risk that child is going to go on to develop a food allergy to one of those foods. It doesn’t mean that it’s guaranteed.

And I think this is another point that Dr. Wood was making, is that food allergy isn’t going away because of early allergen introduction. There are a multitude of causes and there will be children who develop allergy nonetheless, however, it is safe to do early introduction.

Most reactions in young kids are mild, and in those scenarios where families don’t feel comfortable with early introduction, the guidelines actually say, have a conversation with your pediatrician and see what the best next step would be. Whether that be an in-clinic trial, or whether that be a referral to an allergist. We’re here for the food allergy community if they need us.

The first draft of this transcript was created by Descript, an AI transcription tool. An On Point producer then thoroughly reviewed, corrected, and reformatted the transcript before publication. The use of this AI tool creates the capacity to provide these transcripts.