test for food allergy

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If you’ve ever wondered the best way to test for food allergy sensitivity, this episode is for you!

What do I mean by food allergy sensitivity?

Many people think that you’re either allergic (and thus highly reactive) to specific foods or you’re not. And that’s not actually true as there’s a scale of reactivity or sensitivity that you could be on for IgE food allergies.

Making this even more complex is that your level of reactivity can change with time (this is especially true for children) which is why today’s episode is so important!

Food allergy testing isn’t perfect and can sometimes show false positives. Unfortunately, many practitioners (including many in the functional or integrative space) may recommend unnecessary elimination of foods that came back as a positive IgE reaction yet lacked any real-life reactivity.

Though it might seem harmless, it deserves to be repeated that unnecessary food eliminations can potentially lead to IgE food allergy reactivity if left out of your diet for too long.

Throw in chronic skin rashes like eczema, which increase the risk of food allergy (especially in children), and the question of what food is safe becomes increasingly confusing.

That’s why I wanted to bring in a food allergy immunotherapy specialist to talk about this important topic.

So if you’re wondering if skin tests are the gold standard, whether blood tests are accurate, and what the pros and cons are when trying oral food challenges or subcutaneous allergy shots, tune in to this fascinating episode with my guest, Dr. David Fitzhugh.

Dr. Fitzhugh is an allergist/immunologist in private practice in Chapel Hill, North Carolina.

He specializes in food immunotherapy for children and adults with severe food allergies but treats a wide variety of allergic and immunologic conditions, including allergic rhinitis, asthma, atopic dermatitis, mast cell disorders, and anaphylaxis.

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In This Episode:

  • Options that test for food allergy
  • Can positive serum IgE blood tests be wrong?
  • Food sensitivity vs food allergy
  • Benefits of doing oral food challenges
  • What is more likely to trigger a reaction like food allergy hives: subcutaneous allergy shots or oral food challenges?
  • Is it possible to tolerate (to some degree) something you’re allergic to?
  • Oral food challenges dos and don’ts
  • How to reduce your food allergy reactivity
  • Sublingual versus oral immunotherapy
  • Thoughts on elimination diets and food allergies


“In our field, we consider someone sensitized who's test-positive to an IgE test. That could be a skin test or a blood test. So you are sensitized. But if you're test-positive and you eat the food routinely with no issue, you're not allergic, right? Allergic means a clinical syndrome of having an allergic reaction. And where we see this most commonly is the eczema kids.”

“…every allergist in North America is doing subcutaneous allergy shots. These are the typical allergy shots to desensitize people against hay fever, grass pollen, dust mite, et cetera. And we see a decent rate of really serious reactions that occur with those. And so every allergist needs to be prepared to manage an allergy shot reaction, sometimes requiring multiple rounds of epinephrine, IV fluid. Those don't happen commonly, but they do happen. But yet the dichotomy is, there's in many ways a reluctance to do oral food challenge because parents and/or providers are worried about the possibility of reaction. And the thing is with carefully selected food challenges, we have the luxury of knowing where most kids will tolerate, following the blood test to the skin test.”


Find Dr. Fitzhugh online

Healthy Skin Show ep. 269: Allergy Testing: Everything You Need To Know w/ Dr. Stacy Silvers

Healthy Skin Show ep. 327: Demystifying Food Allergy Signs, Symptoms + Skin Rash w/ Dr. Ruchi Gupta

Healthy Skin Show ep. 330: Everything You Need To Know About Dairy Allergy (In Food + Skincare Products) w/ Dr. Stacy Silvers


339: How Sensitive Are You?: Best Test For Food Allergy (IgE) Sensitivity w/ Dr. David Fitzhugh {FULL TRANSCRIPT}

Jennifer Fugo (00:07.436)

Thank you so much for being here, Dr. Fitzhugh. I appreciate your time and welcome to the show.

David Fitzhugh (00:13.102)

Thanks so much, Jen. It's a real pleasure. I'm looking forward to the conversation.

Jennifer Fugo (00:16.62)

So you are here today because I saw a fantastic presentation that you did a few months ago, and you were talking all about food allergies in a way that I honestly didn't even know existed in terms of food allergy testing and understanding how to know how sensitive you are to foods. And when we're talking about food allergies as well, for those who are listening, we're talking about legitimate food allergies, not food sensitivities, not food intolerances.

The big question always is, what are the current tests available to identify food allergies? Is there a gold-standard type of test for food allergy that will definitively tell you if you're allergic to something or maybe not?

David Fitzhugh (01:01.342)

Yeah, of course, it's a question every day in the office and every day when I'm on the street, if people know I’m an allergist, I feel like. So yeah, dating back to a hundred years, we have the classical skin test for food allergy. Skin food allergy test is pretty good, but it's semi-quantitative at best. We're literally taking a tiny amount of allergen and scratching the surface of the skin, typically on the back, and we're looking for an immediate skin response. It looks kind of like a small mosquito bite. And it's pretty good to confirm an allergy with a good clinical history. So by that I mean, if we see a young child who had a history of consuming some peanut butter and 10 minutes later had a food allergy skin rash like food allergy hives and coughing and wheezing and vomiting, that's a really good clinical history. And we're already pretty confident that the test is gonna be positive. And so we just think of the test as a way to confirm that and be really sure about it. And number two, something to track over time. Skin testing has been around for a really long time and it's very good in the setting to confirm an allergy. And it's pretty helpful to rule out an allergy. So a negative skin food allergy test has probably about 95% negative predictive value, meaning if the test is negative, you don't have the allergy.

The problem we run into is they're not good screening tests. A screening test would be a scenario where a child typically hasn't eaten XYZ foods, but the parents are worried, maybe because of eczema, maybe because of a sibling who has an allergy, and they say, hey, Dr. Fitzhugh, I just wanna know if XYZ foods are gonna be safe for my kid. It's a normal, understandable concern, but the dilemma is that a positive skin test with no good clinical story has only about a 50% positive predictive value. That's pretty terrible, right? That means like a positive test is a flip of a coin as to whether or not it's clinically relevant. So skin tests are great to confirm a good story and good to rule out a weak story, but not great in a vacuum, if that makes sense. So we don't like lots of screening tests.

The next evolution behind skin tests has been serum tests or what we call IgE-specific tests. These are a little more direct look. So these are blood tests that are directly looking in the bloodstream for, do you have specific allergy antibodies to whatever you might be interested in, peanut, tree nut, dairy, egg, et cetera. So they are definitely, I would say, a step evolved from skin testing, but they still suffer some of the same problems. They're really, really good rule-out tests, and they're really good to confirm a good clinical story, but we see lots of false positives all the time, particularly in kids with eczema. So we have to be careful not to overuse these and not to send large screening profiles when there's not a good clinical history.

Jennifer Fugo (03:39.124)

Is it also possible with the serum blood test for food allergies to have a false negative as well?

David Fitzhugh (03:46.89)

So it could happen, but it's actually really unlikely. Where these tests shine is what's called their sensitivity. They're really sensitive. So a false negative test is a really unusual kind of thing. It could happen. I think when we hear a story of good clinical history, but the serum test is negative, we'd also do a skin test. And if you had a negative skin and a negative serum or blood test, and still with a good history, you'd maybe want to talk about, you alluded to, “is there a gold standard test for food allergies”? You'd maybe want to think about a clinical food challenge, meaning we actually bring the patient into the office and under careful supervision gradually give small amounts of the food to, essentially, over a couple of hours, understand, is this person going to react or not? And you know, to your question, that is sort of the gold standard. We don't really need to do food challenges for every child who walks in with food allergy, right? If you have a really good story for a clear immediate, you know anaphylactic history to XYZ food and a positive blood or skin test, you know, we're not gonna challenge you but challenges are really useful in several settings.

One is the child that has a weak clinical story and negative or marginal tests, but the parents are really worried, right? Like, you know, I hear a story about, well, my child had some peanut, they've been eating peanut routinely, but their eczema seemed worse three days later and the pediatrician ordered a blood test and it said my child's allergic to peanut. We want to be really careful here. They're probably not allergic to peanut. If we're being super semantic, I would say you're sensitized, which means you're positive on the test, but it looks like you’ve eaten peanut routinely, and we don't want someone who has a low positive test who's never really had any big-time obvious immediate reaction to stop eating that food because they might become allergic down the road if they just stopped wholesale. So that's the kind of scenario where I would either tell the parents if the test was totally negative, hey let's get this food back in the diet, or if the test was slightly positive and/or the parents were worried, we might bring them in for an office food challenge to prove that they're not going to react.

David Fitzhugh (05:46.794)

The other scenario where we might do a challenge is someone who absolutely had a legitimate obvious food allergy, but where it's gone down over time. So we're measuring the blood and the skin test year over year. And perhaps after three or four years, particularly for dairy and egg, where it happens most commonly, it looks like this child's resolving this allergy, but we want to prove in a safe setting that you can now tolerate a full serving of dairy or an entire scrambled egg, for instance. So those are two good times where we might offer what we call an OFC or oral food challenge.

Jennifer Fugo (06:17.656)

Can I ask a clarifying question? Because I think of the patients and caregivers who are listening to this. When you say someone is sensitized, but they're not necessarily allergic, that's what I assume, what does that mean? Your body is, like it's aware of this allergen, but it doesn't necessarily mean that you're having a reaction to it?

David Fitzhugh (06:44.586)

Yeah, it's a great question and it's an elegant question. You know, part of it is just semantics. You know, in our field, we consider someone sensitized who's test-positive to an IgE test. That could be a skin test or a blood test. So you are sensitized. But if you're test-positive and you eat the food routinely with no issue, you're not allergic, right? Allergic means a clinical syndrome of having an allergic reaction. And where we see this most commonly is the eczema kids. So if you test kids with eczema, particularly young kids, less than three, about 90% of of kids, so like fully nine out of ten kids, will have at least one food sensitivity on an IgE test, but the majority of those kids won't develop allergy to those foods that they're known to be tolerant of unless they stop eating them, right? So this is a tension in my world.

Now clearly many kids with eczema will develop immediate food allergies, but before the conversation we just had, I was giving you this good example of a patient I'd seen a few days ago, and it was a child with moderately severe eczema whom I was seeing for eczema reasons. This is a 15-month-old I believe, and one of my questions was, hey, have you introduced all of the common allergic foods now, those being things like dairy, egg, wheat, soy, peanut, even some tree nuts, and they've done all of those which is great. I mean that's in line with what we want parents to do now, early introduction for most kids. And the child was tolerating literally every single one of those with no difficulty at all in terms of immediate reaction. And I'd seen them a month ago, they came back two days ago or so and they said hey, our pediatrician ran a blood test and that blood test, and they actually, I thought this is interesting, the word that the father used, he said, the blood test proves that Johnny, it's not his real name, is allergic to egg. And I said, well, that's really interesting because, you know, I remember you telling me they were eating egg every day with no problem. And he said, yeah, absolutely, scrambled egg is like one of his favorite foods and he was eating it three times a week. But look at this blood test. And I looked at the test and it was an egg-specific IgE blood test, it said 0.87, which is beyond the sort of lower limit of normal. So yes, the test is scored as positive, but it's not meaningful to me as an allergist, right? If you're eating the food every single day, or most days with no issue, I'm not worried about a blood test that is slightly positive.

So I told the parents, I said, hey, I get it, the test is positive, I know that could be worrisome to you. But my point to you guys is, we know that he's not clinically allergic, as things stand right now, and I really encourage you to continue this food routinely, because if you stop, and even if the eczema might improve somewhat, and sometimes you know food driven eczema is a thing which is different than immediate food allergy. But if you stop that food entirely and didn't give any egg for the next six to 12 months, what you're doing is risking exactly what you're describing, Jen, and actually converting this child into now, you have an immediate egg allergy that you have to carry an EpiPen around for and really worry about. So there's this tension here, and I think we need to be really careful not to over test kids who seem to be tolerating foods with no difficulty.

Jennifer Fugo (09:41.736)

Yes and the oral food challenges seems like it could be helpful as you shared in a variety of different ways. I mean, I could imagine for parents and maybe even for the child, it could be stressful because you actually are eating a potential allergy or a food that you have an allergy to, or are wondering if you have an allergy to. Or maybe you're trying to, one thing that was interesting you shared is that, because children seem, some can clear allergies as they get older, you can also use the oral food challenges to understand, I guess, where the child is on that front of things, yes?

David Fitzhugh (10:24.542)

Yeah, that's exactly right. I think, you know, so that is a case where we will leverage routine food allergy testing. And just to give you some common scenarios, say, let's say a two-year-old who had an immediate reaction with food allergy hives and coughing or something to dairy, and they have been strictly avoiding all forms of dairy, but they come and see me at age three and their levels are lower on the blood test or the skin test. And now we're able to introduce some forms. Typically, in that case, we'd start with dairy that's what we call highly extensively heated, usually in a baked product, because that helps degrade the allergen. And even though many kids might still react to, say, liquid milk, they might tolerate it in this sort of heat-degraded form. And let's say that child comes to me yet another year from now, they're now age four, the levels are even lower, they're tolerating baked dairy, and maybe even dairy that's like in pancakes or waffles or something. And now the question is, have you completely resolved this? And for that, we wouldn't generally just suggest someone just try a glass of milk at home. That's a little bit cavalier.

So we'd rather have them come into the office and under careful supervision have what we call a graded challenge where we give a very small amount to begin with, and think in your head sort of stair steps where we're increasing the amounts, and then typically over six or seven steps, usually 15 minutes each step, about two hours total, we've given what amounts to a full age-appropriate serving. And then we'll watch for usually an hour after to make sure there's no subsequent issue. And if someone tolerates a full age-appropriate serving, you know, over a course of three hours, we can really in most cases declare them allergen-free, or at least of that specific allergen, but it's a way to do it carefully and make sure that we're not just missing sort of a high threshold reactor, right, or someone, you know, could tolerate small amounts but once you got to a certain point they actually would still react. Because we want to make sure they can actually ingest a full serving before we say, hey it's okay to eat any form of dairy.

Jennifer Fugo (12:15.38)

Yeah. And I would imagine too, that this can be really stressful because people worry that it could trigger a reaction, but you made an interesting comment in your presentation about which has a greater risk of triggering a reaction, the subcutaneous allergy shots versus a food challenge. Can you talk a little bit about that?

David Fitzhugh (12:37.29)

Yeah, of course. So I think the reason I was giving that talk, this is at the FARE Symposium down in Orlando. And the point of that talk was to say many allergists are not doing as many food challenges as we would like. And in many ways, this is probably a disservice to some patients, because many patients will self-resolve allergies, and/or many patients were slightly positive on a test and maybe are avoiding something that they can actually consume. And the point that I made in that presentation was that essentially every allergist in North America is doing subcutaneous allergy shots. These are the typical allergy shots to desensitize people against hay fever, grass pollen, dust mite, et cetera. And we see a decent rate of really serious reactions that occur with those. And so every allergist needs to be prepared to manage an allergy shot reaction, sometimes requiring multiple rounds of epinephrine, IV fluid. Those don't happen commonly, but they do happen.

But yet the dichotomy is, there's in many ways a reluctance to do oral food challenges because parents and/or providers are worried about the possibility of a reaction. And the thing is with carefully selected food challenges, we have the luxury of knowing where most kids will tolerate, following the blood test to the skin test. And so we're generally not asking parents to come in for an oral food challenge where we think they're likely to react, right? We're generally asking them to come in when we think it's probably resolved. And we can generally predict with probably 80-90% accuracy whether or not a child is gonna pass. So it's not 100%, right? And I think this is the key point, right? I always joke with parents, if I could predict 100% you wouldn't have any problem, I wouldn't drag you in here on a Tuesday and spend half the morning in my office, right?

But the other point to you is that, I mean, your kind of intuition is absolutely correct, Jen, that it's a stressful time, right? Like we might see an eight-year-old who's been avoiding peanut their whole life, and they have been programmed by themselves and their parents in society that this is sort of poison, right? Like, hey, we're going to feed you this thing that might cause you to have a problem. But I always reassure people, look, we're using the best available data to make predictions that your child should hopefully not react, number one. And number two, if by chance they do, and there's always a possibility that they do, even sometimes serious reactions, we’re in a safe place, we're going very gradually, and we're going to stop at the first sign of real reaction.

David Fitzhugh (14:52.608)

So if someone says my throat's itching, I have a few hives on their back or something, we're not going to push this challenge, right? We're going to treat them as needed and stop. So I think, you know, understanding the mechanics of a food challenge, trying to make it a relatively stress-free day are all important, but it's still not easy. And I think it still takes some convincing, and I do think there needs to be some motivation. But the upside is really big, right? Like if you pass this food challenge, particularly if you only have a single food allergen, which is definitely not always the case, but certainly sometimes, you know, we see a child who passes a peanut challenge and that's their only food allergy, everything changes, right? There's no more EpiPens, there's no more food allergy action plans, there's no concern about reading labels.

So I think my message in many ways is yes, there are a relatively small number of us who do many, many food challenges and beyond that, different forms of food immunotherapy for people that might not just lose their allergies on their own. But there definitely are some allergies that just feel reluctant to do them or just don't feel a high degree of confidence. But yet, virtually all of those allergists are doing the allergy shots that could cause serious reactions. So I think my point is, as a community, we need to engage our professional societies and hopefully convince more people to do more food challenges.

Jennifer Fugo (16:15.724)

The other thing that you've touched on actually a couple times already, but that I found most surprising and enlightening about your presentation was when you discussed that there's this level of potential tolerance. You've kind of alluded to that. I thought that if you're allergic to, let's just say, shellfish or dairy or something like that, you're just allergic to it. Like it's like an on-off sort of switch. And that does not seem to be the case, which underscores, I guess, this like increasing challenge. So can you talk a little bit about why it's important to understand how sensitive you are, and how that could also really improve one's quality of life if they could tolerate potentially, well, we might not say a full serving, but perhaps a higher amount in terms of like cross-reactivity or cross-contamination?

David Fitzhugh (17:14.602)

Yeah, it's a great question. I think something that is maybe not well appreciated, that to your point, I think most parents and patients sort of have this perception of food allergy as a binary concept, right? One molecule is gonna cause scary catastrophic anaphylaxis or you can get unlimited amounts if you're not allergic. But the truth of the matter is it's everywhere in between. There are definitely some patients that are highly allergic to, pick your food, dairy, and even very tiny amounts that might be contained in cross-contamination, trace amounts, could cause severe reactions. But then there are patients that might not react until they had a quarter cup of milk. Now, they're still clinically allergic, and they could have a strong reaction when they drank a quarter, half a cup of milk. But nothing happens at lower doses. That's not to say we want them testing the waters routinely, but I think your point is well taken that there's an important improvement in quality of life if you know without a shadow of a doubt that you can tolerate small amounts, because you don't probably need to worry about reading warning labels or going out to restaurants or travel, things like that. Yes, you should not drink a whole cup of milk, but in that scenario, you're just not someone that has to have the same degree of concern as someone at the other end of the spectrum.

So a challenge is one way to figure that out. And of course the ideal outcome of a challenge is someone passes the complete serving, tolerates all six, seven, eight steps, whatever it may be. But I always try to find the positive in everything. And even if we have, I never liked the word failed challenge, actually, that sounds very judgmental and like something went badly. I say reactive challenge in my chart. You did react. It's okay if you reacted. And my silver lining from this is, hey, we kind of know where your threshold is to some degree, because we're going in little increments. So we can say, gosh, you didn't react until step eight or step seven. And I can translate that in real-world terms. That was, you know, like I said, you know, 200 mLs of dairy or something, so you didn’t react until the very, very end. So you probably don't need to worry about small amounts.

David Fitzhugh (19:09.496)

And the other opportunity, not that we hope for this, but occasionally we do see severe reactions in the challenge setting, even despite our best predictions. It's an opportunity to deliver epinephrine in a safe controlled setting. And I really do view this as a silver lining because one of my other kind of soapbox messages every day in the clinic for parents is don't be afraid of epinephrine. This is the medicine that fixes big time problems quickly, and it’s only scary because of the delivery system, right? Like it's an injection, it's going in your thigh, it definitely seems scary to the parents, of course it seems scary to the kids, it's totally normal, but man, this is a hormone your body makes, it is gonna fix the problem quickly. So when we do see serious multi-system reactions in the clinic as a challenge, in a challenge setting, delivering epi quickly and sort of showing the parent and the child that man, this really did work like a charm, no problems, because in the clinic, we have the luxury of knowing, there's no mystery, right? I always kind of tell parents, it's not like in the field or in a restaurant, you say, well, gosh, you have to ask the waiter, look, my challenge was to do a peanut with something in there. There's no mystery, right? In a challenge, we say, hey, we've just given you eight peanuts, so we know that something's happening now as a result of that. But we can immediately give epi and manage the problem, and everything's calmed down typically, and you know, in minutes with no problem at all.

So I think there is a real kind of teaching opportunity. Now we don't want to encounter that, but if we do there is a silver lining, and also to your point about understanding, hey your threshold might be pretty high. You may not be somebody that really has to worry about cross-contamination, warning labels, all those kinds of things that are really, really impactful when we think of the psychosocial dimension of food allergy, which is something that people think about the medical dimension, right, of worry for serious anaphylaxis, going to the hospital, EpiPen.

But there's this whole aspect of food allergy with the psychosocial aspect where, you know, things are just different for kids with food allergy, right? They're sometimes socially isolated, sometimes stigmatized at school, you know, they can feel alone. There's a whole, you know, unfortunate scenario of food allergy bullying that occasionally happens. So these are things we really need to think about and be concerned about. And I think any time we have the opportunity to clear someone of this food allergy label, we should take it.

Jennifer Fugo (21:24.736)

Yeah. And for somebody who's like listening to this and going, you know, maybe this is something we should consider doing because they're either supporting, they're caregivers supporting a child, or maybe they have a spouse or someone else in their life, or they themselves have food allergies and wanna understand maybe a bit more. Like I said, it's not the you have it, you don't. There is a sliding scale here that would be important to know. What are some things that they should know ahead of time going into oral food challenges like do's or don'ts that would help them better prepare for this?

David Fitzhugh (21:59.55)

Yeah, I think most clinics doing this should hopefully give you some information, but sort of broad strokes, things that would be helpful. Number one, just in terms of medications, we want kids generally off of all allergy medicines or at least oral antihistamines for about five to seven days because that can falsely mask a challenge reaction. We definitely want people to have well-controlled asthma. Uncontrolled asthma is the number one cofactor for more serious reactions. So a child that's on daily controller inhalers, we absolutely want those to be on board. And if someone had been ill recently within 14 hours leading to a challenge or had an asthma flare, we would want to reschedule that challenge.

Other aspects for practical things, you know, as we talked about just a minute ago, it can be scary for the child. So bringing in kind of comfort items and a young child, a favorite blanket or stuffed animal, and an older child, adolescent, things that help keep them occupied, because it's a long morning or afternoon, right? Typically three, even four hours. So, you know, whether it's, I'm not a huge fan of excessive screen time, you gotta do what you gotta do as a parent, right? So whether it's iPad, you know, Game Boy, whatever, you know, those things are really useful to keep kids occupied.

And then particularly in infants and toddlers, you know, the challenges can be challenging, no pun intended, in the sense that just delivering the food is sometimes hard if we're trying to sort of do a baked challenge and can't get the kid to eat the food. So things that they're familiar with, whether it's, you know, their own sippy cup for a liquid challenge, or whether it's a favorite sort of like, you know, spoon with Elmo on it or something, all of those things can be practical and it can be helpful.

Jennifer Fugo (23:34.516)

And is it okay to eat before the challenge or is it best to come in fasted?

David Fitzhugh (23:38.454)

Yeah, best to come in fasted. We want kids to be hungry and we don't want there to be other foods complicating the challenge. Now typically during a long morning or afternoon, we actually will permit them to eat their known tolerated foods. That's OK. But we don't want them to come in on a full stomach. Otherwise, they sometimes won't want to eat any food, which is obviously a difficult part of the challenge.

Jennifer Fugo (23:55.064)

Fair enough. Absolutely. So if somebody is reactive to something, and this could be, maybe you have a different answer for children versus adults. I don't know, but that's why I wanna ask, is it possible to reduce reactivity at all once the test results are kind of final?

David Fitzhugh (24:17.773)

Yeah. Of course, so if we have a, as I said, not failed, but reactive challenge, there are definitely options for those people. Of course, the classical advice that you would get is still strict avoidance and here's an EpiPen, that's still been the standard of care, but there is a small and thankfully growing group of allergists that are really embracing technologies and therapies to reduce the reactivity. Foremost among those, and at least sort of what has been around the longest is what's called oral immunotherapy. It’s eating small but increasing amounts, leading to often a full serving of, call it, peanut, dairy, egg, et cetera. OIT's been around for a while. There's one actually FDA approved product called Palforzia that's been available since 2020 for peanut oral immunotherapy. It's an intensive therapy. It takes a lot of time and effort on the part of parents, caregivers, et cetera. And there are risks associated with it. People can have mild side effects, particularly GI symptoms. Occasionally they can have serious reactions to the therapy itself. Those don't happen often, but they could happen.

And there's other technologies in the pipeline. We do oral immunotherapy in my own practice, but in the past year, we've really started to embrace an alternative, which is called sublingual immunotherapy. So what this means is allergy drops under the tongue. And the big difference is it's a much, much lower dosing scheme than oral immunotherapy. So whereas in oral immunotherapy, we might go to four whole peanuts, which is about a thousand milligrams of peanut protein, that's a pretty high allergen load. The sublingual, it goes to usually two milligrams, so 500 times less. It definitely works, but the trade-off you're making is speed for safety. It's a really, really safe therapy that virtually never causes serious reactions. It just takes longer to show results. But many parents are on board with that, and particularly for older kids or kids that are very highly sensitized, meaning on the high end of the spectrum, it's much easier to do. The oral immunotherapy in particular, it does work very well, but it is best for younger kids that are sort of pre-adolescents and younger and sort of on the lower end of the sensitivity spectrum in terms of those blood test numbers in particular is what we like to track. So those are the two major options in the U.S. right now.

There are other things coming that are exciting and I think, you know, of course no one really wants to have a food allergy, but this is not a bad time to have a food allergy in the sense that there's so much more technology that's coming. There's a peanut patch that's been in development for quite a while that's in late phase three trials. I think we'll likely see that come to market in the next couple of years, and the people that make that patch will probably leverage it, of course, for other food allergens. So I think we have at least three technologies coming, others on the horizon. So it's an exciting time where I think we have a lot more to offer than what was, honestly, I've been in practice 11 years. The beginning of my practice lifetime was just quite depressing to see these food allergy kids. Not from a “we don't want to help you,” of course we want to help you, but hey, here's the EpiPen. Let's run your test. We'll see you in a year. That's just not a very satisfying therapeutic kind of interchange with the parents, but we have so much more to offer now.

Jennifer Fugo (27:23.376)

Yeah, that is exciting. And since you talked all about oral food challenges in your talk at FARE, and here we're having this conversation. There has been something that, as many of my listeners know I'm really big on reducing the amount of foods that we just kind of do a knee jerk reaction of pulling them out of the diet. Because in the skin world there's so much information online, it's overwhelming, that people will self-eliminate extensive amounts of food for extensive periods of time. And in talking with other nutrition colleagues who are dietitians and other clinical nutritionists, what we have sort of pieced together, at least at this point, is that when people do this, especially with one of the top nine allergens. I haven't seen it when it's like outside of the top nine, unfortunately, but usually with the top nine, not everybody, but sometimes when the person's really strictly avoided this food in the top nine, they go to try to reintroduce it, at some point around a year seems to be the timeframe where you potentially could trigger that IgE-mediated allergic reaction to a food that they never reacted to before. And it is devastating because they partly feel like they did it to themselves.

David Fitzhugh (28:52.266)

Yeah, absolutely.

Jennifer Fugo (28:53.388)

So what are your thoughts on this? Again, these are in adults. I don't work with children. So I can't necessarily speak to that, though, obviously, you've mentioned, you shared that story of the child and the warning even to parents that we've got to be careful in children. So what's your thoughts on this? And then also for an adult in this boat, or maybe even a child who didn't previously have an allergy, if they did eliminate a top nine allergen for an extensive period of time, do you think oral food challenges might be a good idea?

David Fitzhugh (29:25.43)

Yeah, it's a complicated question, but certainly a good one. And I think your point is well taken. It's sort of a cautionary tale, right? Like people that were very well intended that for XYZ skin condition or IBS or gluten intolerance, it's, hey, let me take out dairy, egg, wheat, soy, and sesame and maybe I'll feel better. And then 18 months from now, they have legitimate immediate allergies to XYZ food. Of course we want to avoid this. So I think the challenges are severalfold.

One is, it's not clear that dietary restriction is always going to solve all problems. I think, you know, just to give you some sense in the eczema literature, there was a nice study published a few years ago that looked at parents with kids with eczema, and they just interviewed them and said, do you think your kid’s eczema is driven by foods? And 95% of them said yes, right? So like essentially the overwhelming majority. But then when eczema was under good control, which is normal medical management, appropriate tools, topical therapies, et cetera, and things were going smoothly, they asked the parents again the same question, do you think your kid's eczema is driven by food? And the answer is only about 10%, right? And so I think here's a lesson right there to say, it's not impossible that foods drive specific skin states, but it is not always the case, and let's make sure we're managing the disease state with current standard of care. So that's one lesson.

But to your bigger point, in an adult who, for whatever reason, does choose to rigidly eliminate a top nine allergen over the course of an extended period of time, call it 12-plus months, they definitely are at some risk of developing a true immediate/IeE-mediated food allergy. I wouldn't say they're actually all at high risk. And the highest risk is actually, and I know you don't work with kids, but the highest risk is actually younger kids because the immune system is much more plastic. So when I see these kind of like 12 to 24-month-old toddlers, I'm really, really worried about unnecessary restriction because if they're, you know, taking out foods they don't need to be, even if we're driving eczema to a certain degree, but they're not reacting immediately, my phrase for these parents is always short-term pain for long-term gain, right? Like I'll put up with some mild-moderate eczema even if the food is driving it, as long as it's not an immediate reaction. And let's get through this.

David Fitzhugh (31:36.826)

It's been shown that by the time kids get to about age three, a lot of these low-grade food sensitivities just completely resolve. If you look at skin and blood tests, and now they can continue to tolerate all foods, assuming you didn't eliminate one or more for a long period of time. But circling back to your question about the adult, and what do you do now? Someone has eliminated their food for a year or more, and now they're gonna reintroduce it. They tell you, look, it didn't make any difference. I took out wheat, soy, dairy, and sesame for 2 years, I feel exactly the same, my skin's no better, but I want to get back my diet. Do I need to worry, do I need to bring this person in?

The answer’s maybe. I would say if that person was known to be an atopic individual before, meaning they are an allergic individual, they have hay fever, asthma, or known eczema, I think you want to be really careful with that kind of person, and that's the kind of person that we might want to test beforehand. So we probably bring that person in, do a skin and probably also a blood test and figure out, have you actually sensitized yourself enough? Remember, sensitization, positive on a test, but enough to be clinically allergic. And we know particularly from the blood test that above a certain cut point that you might now be clinically allergic and manifest an immediate reaction. I don't think everybody necessarily needs to be tested, you know, someone that was never an allergic kind of individual before, meaning someone who really didn't have any history of asthma, eczema, hay fever, food allergies earlier in life, call it, you know, the first 20 years of life. To be honest, they probably don't need to be tested because they're probably not at a high risk of having developed that sensitivity that's pushed into a true food allergy.

But my answer to that question would be a year or more of restriction and any significant allergic history, iIt doesn't have to be food allergy. I'll make that point, right? Even someone with pretty bad spring pollen allergies, they might be someone who is IgE-sensitized and now it's become a true food allergy. So we want to keep those people safe.

Jennifer Fugo (34:07.048)

So I love hearing about all of this. I love learning about all of this. And I know that listeners really appreciate this. You are in practice and you are accepting patients, yes?

David Fitzhugh (34:32.938)

Yes, I am. I'm in Chapel Hill, North Carolina, and we see patients all throughout North Carolina and sometimes states even beyond. It's certainly in the Triangle region, so we're all here in Chapel Hill. I do not exclusively, but mainly food allergy and food immunotherapy, and I have two associates that are terrific in managing all the same conditions as well. And certainly, we're happy to see anybody who might want to come see us and benefit from our knowledge and expertise.

Jennifer Fugo (34:57.768)

Awesome. And for those of you also who are, maybe, live far away, there is a website called fastoit.org. We'll put the links to everything in the show notes. That way it's really easy for you all to find whatever you need and to connect with Dr. Fitzhugh as well. So Dr. Fitzhugh, thank you so much for your time and I hope that you'll come back and we can talk more about allergies in the future.

David Fitzhugh (35:19.21)

Oh, I'd love to. Thanks so much. It was really enjoyable and I hope your listeners got something out of the conversation.

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