DocTalk Podcast: What Causes Food Allergy? With Whitney Morgan Block


There has been significant changes in understanding surrounding food allergy testing. What do parents need to know?

So much of clinical understanding surrounding food allergies is currently in flux. Food immunotherapies may soon become available on the US market, major pediatric trials have recently reshaped treatment guidelines, and yet, the communication and understanding of food allergy between care givers and pediatric patients’ parents is still mostly disconnected.

In fact, in some cases, the information that may be reaching pediatric patients and their parents may be dated, inaccurate, or even potentially harmful to their care. There’s never been a better time to share a comprehensive update on food allergy.

To help lead that discussion, Whitney Morgan Block, MSN, CPNP, FNP-BC, president, chief executive officer and founder of the National Allergy Center, joined MD Magazine® for a three-part DocTalk series on preventing, diagnosing, and eventually treating food allergy.

Here is the first part of the chat, on cause and prevention.

Here is part 2 of the chat, on diagnosis.

Here is part 3 of the chat, on treatment.

For more of the DocTalk Podcast, be sure to subscribe on iTunes.

MD Mag: Hello, everybody, and welcome to the DocTalk podcast. I'm Kevin Kunzmann, managing editor of MD Magazine, and I'll be your host for this three-part edition of DocTalk on food allergy care with Whitney Morgan Block, president, CEO, and founder of the National Allergy Center.

Before we kick off the talk, Whitney, could you give our listeners a little bit of background on who you, your experience, and if you have any relevant disclosures, you could list?

Block: Yeah, it's great to join you today. As you said, my name is Whitney Block. I'm a nurse practitioner, and I graduated from Johns Hopkins and got my masters from Vanderbilt on a dual-certified nurse practitioner. So I specialize in pediatrics and families. Right after graduation, I worked for the CDC for a little while. And then I worked at Stanford University at the Sean N. Parker Center for Asthma and Allergy research. I worked there for about 6 years before I started my own private practice, the National Allergy Center. And now we've got multiple locations throughout California, and we're looking to expand nationwide.

MD Mag: Okay, great, thank you so much. That’s a lot of relevant background for this pretty comprehensive chat we're going to be having today on food allergy. And for this first episode, I think we should dive into cause and prevention measures in food allergy. And maybe you can just help set a foundation for the rest of this chat, and lay out for us: what are the most common food allergies afflicting patients in the US today?

Block: So when we talk about food allergies, most people talk about kind of the top 8. And now it's soon to hopefully be the top 9. But the top 8 food allergies include milk, egg, wheat, soy, peanuts, tree nuts, fish, and shellfish. And really coming up in kind of a ninth place is sesame. And there's a lot of talk about sesame now, and there's a lot of new sesame allergies being diagnosed. So people are petitioning the FDA to actually have that be the ninth allergy, so it's listed on labels and cautionary labels, and that kind of thing. So those are kind of the top 8, top 9. But in reality, anybody can be allergic to anything. So even though those are the kind of most prevalent, anybody can be allergic to any food. So I’ve definitely come across some of the weird outliers foods as well.

MD Mag: Right, that's fairly good points. And to mention too, you know, it's not as if we're pigeonholing all these patients into just, you know, sets of 10 different conditions that can really afflict them in so many different ways. When we're looking at the drivers of food allergies, presenting in patients, what are the most common drivers that we're seeing?

Block: There's a lot of different theories out there about what is causing these food allergies. And really, what it comes down to is we really don't know, but we think there's not going to be one answer. It's going to be a multifactorial reasoning behind why people are developing food allergies. It's going to be a mix of genetics, and a mix of the lifestyle and natural factors in the environment. One of the big things that people talk about nowadays is about the hygiene hypothesis, which you've probably heard of, that we're pretty much been to clean.

And we're using a lot more detergent, we're using a lot more pesticides, we're just trying to be as clean as we can in the environment. And that really seems to be affecting our our guts and our microbiota, and the good bacteria that we have on our skin and inside our bodies. And that might be one of the driving factors behind whether or not somebody develops a food allergy. So, when we talk about the driving factors, we also try to think about, well, if we know what drives it, what can we do to help prevent these food allergies?

And I always like to think of things as like the 4 D's, and the first of the 4 D's being dry skin. It seems like if people get introduced to allergens through their skin—which is kind of an unnatural way of getting introduced to foods, where the natural way is through the gut. If you get introduced to it through the skin, you might be more likely of developing an allergy to it. So if you have a baby, in particular, that has eczema or dry skin, you want to make sure that you use a lot of emollient, some moisturizers to protect that dry skin, so they're not exposed that way.

The next D would be diversification of the diet. So making sure that we're introducing foods at a young age, between 4-6 months old. I can tell you that when I was in nursing school, which wasn't that long ago, I was taught to hold off on introducing peanuts until age 3, hold off on introducing milk and shellfish until 1—you have to introduce the fruits and veggies first, and then you move on to eat cereal, and then you had all of these kind of stages of how you're supposed to do it. And now, mainly because of the LEAP study, which we can get into in a little bit, that reasoning or those guidelines have really been turned on their heads.

Now, the new guidelines are between 4-6 months old, you should be introducing all foods, allergenic or not. Really the only exception to that is honey, obviously, because of the botulism risk, but any foods as long as it's a non-chokeable food, and you can do it in a non-chokeable form, you can introduce peanuts and tree nuts and shellfish starting at age 4-6 months—whenever the baby is starting to eat solid foods. So diversifying the diet early is going to be really important.

The third D is dirt. So, don't be too clean. Own a dog. We know that owning a dog, especially a dog that can go outside and inside, they bring some of that good dirt and that good bacteria inside the house. And it actually helps with allergies. And it can help with food allergies, it can also help with asthma. And we think that that might be a player in helping out to prevent allergies from occurring.

And then the last D is vitamin D—making sure that you have healthy levels of vitamin D and you're not deficient in it. So there's the 4 Ds: dry skin, diversifying the diet, dirt, and vitamin D. And those are what I always explained to parents about what are the factors that we can kind of change that might help prevent food allergies from occurring. But in all reality, even if you do all of these things, there's still people that have food allergies. And we don't know exactly why some people develop food allergies, and some people don't.

MD Mag: Well, it's fascinating to think that our understanding of it is still evolving. But thankfully for now, we have a very helpful mnemonic device to provide advice for these patients and their parents who are trying to understand it better. That's great. Thank you. And we're certainly going to be talking about some of the most frequently diagnosed allergies in a bit here. But for now, maybe we can get into the most under-diagnosed. What's sort of slipping by, in terms of food allergies, and maybe what's driving that?

Block: So really, we don't in the allergy world talk about much about under-diagnosing allergies. Actually, the problem is the over-diagnosing of allergies. Most people, if they have an allergy, they know about it, and either they know about it because they've had a reaction to it or because they've had a reaction to something else, and then they get tested for it.

So we don't really talk that much about under diagnosing and going out there and trying to figure out what people are allergic to. I would say one of the trickiest allergies is probably sesame at this point, just because it's not labeled on all of the food allergies labeling. And so sesame is a really tricky one. Some of the seeds are also pretty tricky. It's like poppy seed, chia seed, and flax, that kind of thing. Sometimes they come in kind of trendy or foods that try to take out certain proteins by adding in other proteins, and other proteins being proteins that are used in other foods. And so those are kind of the trickier ones when somebody says 'Hey, I've had an allergic reaction to something, let's try to figure out what it is.'

Those are some of the ones that people don't think about as much, just because they're not part of the top 8 technically.

When we talk about over-diagnosing food allergies, though, this is a really big problem. People ask me all the time, if I have any personal experience with food allergies. And I actually don't have any food allergies myself.

However, after I got working in food allergies, and I've been working with food allergies for quite some time, my sister calls me—I live in California, my sister lives in Charlotte, North Carolina—and my sister calls me when my nephew, her son, was 10 months old. And she calls me freaking out, because Baxter had a little bit of peanut butter. And she swears he had peanut butter before, and he was totally fine. But this time, he grabbed some peanut butter off of her spoon, super knowingly, and he started screaming, he started getting red in his face, hives all over. And my sister was freaking out, obviously, about what to do.

And there's only so much I can do from 2000 miles away, but we get that reaction under control. And I tell her she's got to go and find an allergist to get tested. And he went and got tested. He got skin testing first, which is one of the most common ways to diagnose a food allergy or help diagnosis food allergy—which is little scratches either on the back or on the arm, with a little bit of the allergen to see what kind of reaction you get.

And luckily, he tested positive for peanut, but that was it. He tested negative for pretty much all other tree nuts and everything. But the allergist, instead of saying, 'Okay, let's try to get some of these negative foods into his diet,' they said 'Hold off, let's get a blood test first,' which was fine. He got a blood test. And he tested really positive for peanuts, and he tested slightly positive for all of the other nuts.

And so instead of saying 'We should do some food challenges, we should look for reasons to get these foods into his diet, everything except for peanuts,' they said 'Avoid everything. Avoid everything, avoid peanuts, avoid tree nuts, avoid everything that he tested positive to in his blood, and we'll see you next year. We'll see you next year for a follow up.'

And at that moment, I kind of had a little heart attack. I said 'Whoa, you're not going to do that. Okay, I know that sounds really weird. I'm telling you don't follow the advice of you, the doctor that you just saw.' But the truth is, is that we really need to look for reasons to challenge people and to safely get these foods into his diet. I mean, I don't have any hardcore proof saying if he actually avoided, he would develop those allergies. But we do know that the longer you wait to introduce those foods, the more likely you are that he would have those allergies, he would develop those allergies.

So luckily for her, and luckily for Baxter, we were able to safely introduce all those foods into his diet, except for peanut. And we did therapy for peanut, and now he's eating the equivalent of like 2 peanuts every single day, and is a happy, healthy toddler. He still curious around epinephrine wherever he goes, but she is not as freaked out. And I just talked to her on the phone last week. And she said Baxter actually accidentally took a bite of a Butterfinger instead of a Milky Way that she thought he had. And she took it away from him, and he didn't really like it, but nothing bad happened. He didn't have a reaction to it. And more so, my sister didn't freak out like she did when he was 10 months old.

So therapy definitely does wonders. But we really need to change the way we think about diagnosing food allergies, and make sure that we're telling the correct people to avoid and not over-avoid any foods.

MD Mag: Accidentally having the Butterfingers is a great example of exactly why that small exposure, frequent enough to make it less of an issue, is a great example of immunotherapy that we'll talk about later. But it's also emblematic of something that I went through myself personally, if I could share right now. I had a food intolerance to seafood growing up since I was an infant. And my parents assumed it was an allergy, without an official diagnosis.

I didn't find out until years later, it was simply just an intolerance that was shown when I was an infant. And in fact, I had to eventually ween myself on to things like salmon and other seafoods to be able to enjoy them. So that I think it's also a pretty good segue into our next topic here, which is the biggest false assumptions that patients and even physicians may have about food allergies—and I have a feeling that you're going to talk about those fake diagnoses or misinterpreted reactions to food.

Block: Yeah, so I think the biggest false assumption is that if you're allergic to q food, you have to avoid other foods. If you're allergic to 1 tree nut, you have to avoid all tree nuts. That's a huge one. And people will say, 'Oh, I'm allergic to tree nuts.' And my next question is 'Really, which ones?' And then some people look at me kind of crazy, like a tree nut is an actual nut. And a tree nut is not just one nut. Tree nuts are like cashews, pistachios, almonds, hazelnuts—all of these nuts are all considered tree nuts.

And yes, some of them have related proteins to them. But just because you're allergic to one does not necessarily mean you're allergic to the other. So you really want to—especially when you're talking about diagnosing, if you get tested—you want to make sure you get correct testing and relevant testing for the actual person.

It's kind of one of my pet peeves, when it comes to other allergists and primary care physicians, and even patients that come up to me and say, 'I just want to know what I'm allergic to. Can you just order a panel?' And I say, 'I have no clue what kind of panel you're talking about.' Because there's no such thing as a food panel that's going to figure out about what you're allergic to. It's going to be really specific to that person in their history, and what exactly we need to test them for, because we don't want to test for things that they're not allergic to—that they're already eating, for instance. I hate it when people get tested for food that they're eating on a regular basis. And then the test comes back positive, and they say, 'Oh, well I must avoid this now,' even though it's a totally safe food that they've eaten every single day of their lives, maybe. And now this one test is telling them that they're allergic—that test does not tell you that you're allergic.

The blood tests and skin test both are guides to let us have more information about whether it's safe to do a food challenge, and what the likelihood is that you're going to have a reaction if you were to eat the food. It does not tell you if you're going to have a reaction, at what level you're going to have a reaction, or what severity the reaction would be. And that is very mystifying to a lot of doctors and a lot of patients, that it's not a gold standard test. The gold standard test for diagnosing food allergies—there's only one at this point, and that is a food challenge. That is, can you actually eat the food and not have a reaction to it? All of the other tests that we do, the blood test and the skin test, we just use them as guides. They're tools. They're not actually diagnostic tests.

MD Mag: Well, honestly, that's actually very useful information, from my own perspective. I know that's that was something that was a big, false assumption for myself, before coming into the medical coverage field—of understanding exactly what people were actually gaining from the food allergy test. So thank you for that.

And lastly here, when we're talking about these allergy preventive methods, we've touched on all the causations and those initial steps towards a diagnosis. But what sort of preventive measures can we also share to our patients that they can adopt, or maybe physicians can just recommend to a parent?

Block: So I think it's really important not to place blame. I think when we talk about how to prevent food allergies, a lot of parents come to me saying, 'What could I have done differently? Should I have eaten more peanut butter while I was pregnant? Should I not have eaten peanut butter while I was pregnant? Should I be eating peanut butter while I was breastfeeding? Should I not have all of these things?'

Especially when it comes to second kids—'My first kid has a food allergy. How do I prevent this one from not having a food allergy?' And we need to make it really clear that we don't know. We don't know the cause. There has been no evidence whatsoever that states whether or not eating nuts while you're pregnant or while you're breastfeeding is going to prevent or cause food allergies. We really don't know. So the guidance is to eat a healthy diet while you're pregnant and continue to eat a healthy diet while you're breastfeeding, regardless of whether or not you have a kid with a food allergy, or without a food allergy—as long as it's a safe environment for the child and it's a healthy environment for the mom. That's what we're we really care about. So just make sure everybody's healthy.

The other thing is making sure that we're telling patients to introduce foods at an early age. So, introduce foods between 4-6 months old. And once you introduce a food, keep it in the diet. It's not like a checklist of, here's all the foods that I need to introduce, checking off yes, I introduced peanuts, and now I don't actually have to give it to them ever again.

Once a food is a safe food and you introduced it into the kid's diet, you want to make sure it's in the diet on a regular basis. And that's really important when it comes to food allergies. It's not just introduce early, but it's also introduced often. The LEAP study, which I kind of alluded to earlier, was a groundbreaking study that was done out in the United Kingdom. And what an allergist did and kind of noticed in the United Kingdom was that a lot of babies in Israel didn't have peanut allergies. And she was trying to figure out why that was so. And one of the things that Israeli kids eat from a super young age is this little snack called bamba. Have you ever heard of bamba?

MD Mag: I have not.

Block: So, bamba, it almost looks like a Cheeto. But instead of cheese powder on the outside, it's got peanut powder. So it's a very safe food for babies, because it kind of dissolves in their mouth, it is really protein rich, because it's got a lot of the peanut dust on the outside. And it so it's really easy to introduce to babies as one of their first food. And so, Israeli kids get introduced this at a really young age. And because they got introduced early, and they got to introduce often, that's the reason why we think that they might have fewer peanut allergies over in Israel. With that thought, Dr. Gideon Lack in the United Kingdom did a really huge research study on a whole bunch of infants. They pretty much got a whole bunch of infants, skin tested them, and put them into 2 groups—either skin test-positive, or skin test-negative.

The thought was that the people in the skin test-positive group—as long as they did not have a reaction to peanut prior to entering into the study—if they're in skin test-positive group, our thought was, you might be more at an increased risk, or you might be at an increased risk of developing a peanut allergy. And so what he did between both the groups is he split those groups into 2, and he said half of the group is going to introduce peanuts—either in the form of bamba or watered-down peanut butter. But most of them were on bamba though, because it was kind of easier.

They were going to introduce peanut, about 2 grams of peanut protein, which is the equivalent of about 8 peanuts, 2-3 times a week. And then the other group was going to avoid altogether. And what they found out was that introducing peanut between 4-6 months old, reduced their risk of developing a peanut allergy by 81%. And that is staggering.

MD Mag: Wow.

Block: Exactly. Wow is right. That is totally crazy. Because I mean, everything in the United Kingdom and the United States, in Australia, in Canada—all of our guidelines for such a long time were to hold off on on introducing these allergenic foods like peanut until way later, because if we introduced later, we thought we could kind of fend off the allergy. And that's the reason why this one study turned all of those guidelines kind of on their heads and said, 'Wow, maybe we're not telling people the right thing. Maybe if we introduced the food earlier, we would actually prevent these kids from having peanut allergy.'

And obviously, it did not work for everybody. And all studies have issues, compliance issues, and everything like that. But the truth is, the majority of the patients that were introduced peanut—even if they were at the what we thought as an increased risk, because they had eczema, because they had this positive skin tests and stuff by age 5—by the time that you were going off to kindergarten, the majority of them that were in that introduce people group, they didn't have a peanut allergy. And that's great. And that's amazing information for us to have.

And we need to make sure that all pediatricians, all primary care physicians, anybody working with any newborns or any 4-6 months old, they need to have that as part of their well-child checks—of okay, it's time to introduce foods. Let's make sure we're not scared of introducing peanuts and these other allergenic foods. We need to get them into the diet early, we need to do it often. We need to make sure we're not living in the past, because living in the past means possibly contributing to some of these food allergies.

MD Mag: That's such a hopeful note to end this part of our discussion on. That's really great. We're going to get into immunotherapy and overall treatment in care for food allergy in a bit here. But, regarding cause and prevention, anything else you'd want to add Whitney, before we sign off?

Block: I don't think so. I think that the other thing that I would say is, only so much can happen primary care office. I worked in a in a primary care pediatrician's office for a bit. And I know those visits are really short. And I know parents have a lot of anxiety, especially around food, especially as they have loved ones or another sibling or something like that with a food allergy.

And so if you have any parents that are nervous about introducing foods, I would highly recommend reaching out to an allergist, reaching out to psychologists, getting the support they need to be able to safely introduce foods into a kid's diet. Because if you just kind of gloss over it and you wait, it could go against you in the future. So you want to make sure everybody's proactive about it, even if there are obstacles and hurdles in the way. The more we can prevent, the less we have to treat, and that would be awesome.

MD Mag: That's a great motto, that's a great slogan, a great action point to build off of, and I think a great conclusion to our first part here. So that's all we have for this segment of our three-part chat on food allergy care. Whitney, thank you again for taking part with DocTalk podcast, and thank you to all of our listeners for tuning in. Be sure to check out parts 2 and 3 on the diagnosis and treatment of food allergy. And for the latest news, be sure to head to I'm Kevin Kunzmann. Thanks for listening.

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