DocTalk Podcast: Diagnosing Food Allergy with Whitney Morgan Block


How can physicians and specialists navigate testing options and potential risk factors to ensure patients are diagnosed and treated expediently and accurately?

The prevalence and incidence of food allergies including peanut has been rising in pediatric patients. Patients of inflammatory diseases, including atopic dermatitis, have also more recently began reporting greater rates of allergic-type reactions to food. And another study from earlier this year showed about 1 in 10 US adults have a convincing food allergy—but nearly double that amount believe they suffer from an allergy.

For all the uncertainty in food allergy testing and strict diagnoses, broad trend assessments show diagnoses are on the rise. It’s critical physicians know what patients are at risk food allergy, what are the misconceptions around certain testing methods, and what resources and specialists they have at their disposal to optimize both patient diagnosis and care.

In the second segment of a three-part DocTalk podcast on food allergies, Whitney Morgan Block, MSN, CPNP, FNP-BC, president, chief executive officer and founder of the National Allergy Center, discussed diagnosis with MD Magazine®.

Here is part 1 of the chat, on cause and prevention.

Here is part 3 of the chat, on treatment.

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

MD Magazine: 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. The first part of our conversation touched on food allergy cause and prevention, and it started to extend a bit into our next 2 topics here. But for now, let's focus strictly on diagnosis.

How exactly do we define food intolerance versus food allergy? I know this is something we touched on in the last talk. But regarding the importance of defining the 2 from one another, could you dive a bit more into that?

Block: The difference between a food allergy and food sensitivity or intolerance is the body's response to that food. When someone has a food allergy, their IgE is triggered to respond. So inside your body, you have mast cells and inside the mast cells, you have pockets of chemicals like histamine, leukotriene, cytokines, all these inflammatory chemicals. On the surface of the mast cell, you have IgE receptors that are on the lookout for things that you're allergic to. And as soon as your body sees something that it's allergic to, it will bind to that receptor site and send a signal inside the cell, telling the cell to explode and release all its contents. And when your cell explodes and releases the content, that's what triggers you to have those reactions, like itchy mouth, abdominal pain, vomiting, hives, trouble breathing, sometimes a drop in blood pressure, those kind of reactions.

When you have a food sensitivity or intolerance, the reaction is triggered by the digestive system. When you eat a food, when you bite into something that you are sensitive to, you're intolerant to, it might cause bloating or headaches. You have those kind of reactions, but they're not fatal reactions. It's not IgE-mediated, and you can't die from a food sensitivity or intolerance. People are really confused between that and celiac disease, because celiac disease is actually an autoimmune disease where your immune system responds by damaging the small intestine when it eats some form of gluten. It's not an allergy, it's not IgE-mediated.

People are confused about this because of what gluten is. Gluten is actually a family of proteins found in grains like wheat, barley, and rye. And you can actually be allergic, IgE-mediated allergic to wheat, barley and rye. So you can have celiac disease, which is an autoimmune disease, at the same time is having an IgE-mediated reaction to some of those gluten proteins.

MD Magazine: And if we could focus in more particularly right now into pediatric diagnosis, could you explain for us exactly the importance of an early initial allergy test for children?

Block: So we talked a little bit in the last segment about overdiagnosis. So I want to be really clear on, if you have a patient that comes in and they have eczema, that doesn't necessarily mean they're going to develop food allergies. That is kind of the first part of somebody with a food allergy—they could have eczema, but not everybody. Only about 30% of kids with eczema will actually develop a food allergy.

So I don't want all primary care doctors to say, 'This kid has eczema, I want to get them allergy tested.' That's not the way to go. You're going to have a lot more overdiagnosis, and a lot more freaked out parents if you do it that way. So it really is on a case-by-case basis, but don't make a blanket rule of anybody with eczema needs specific food allergy testing. Also, looking at family history.

The other thing that I hear a lot of is 'mom has a peanut allergy and dad has asthma, so the kid must have some kind of food allergy.' The thing is, is that we think that there's a allergic cells in the body. So there is definitely a genetic component to food allergies. But just because parents have allergies, regardless of whether they have food allergies or not, the kids still have the risk of having an allergy. Or, if your parents don't have any allergic disorders, there is still a chance that the kid has a food allergy. So you can't really look, but you definitely can't say 'Oh, so and so has a peanut allergy. So my kids going to have a peanut allergy.' There's not that direct connection whatsoever.

Like I said, there is some kind of allergic gene in the body. But just because parents have allergic genes in their body, that means that the kid is more likely of having an allergic gene. Whether that's actually expressed as a food allergy, or whether it's expressed as a penicillin allergy, or whether it's expressed as asthma or allergic rhinitis, we don't know how it's going to be expressed. But don't automatically assume the kid must have a food allergy.

It's really important to take care of kids' skin, though, at a super early age. So even before they're introduced to foods, we want to make sure that their skin is taken care of really well. So you want to use a lot of moisturizers and emollient on the baby's skin. If you think that it's your out of your control, don't hesitate to refer to an allergist or dermatologist to try to make sure that we can do whatever we can to get it in control, for the sake of potential food allergies and asthma and preventing the allergic march from happening—which, we can get into the allergic marches in a second.

But also, to make the kid as comfortable as possible. I mean, I think all of us have probably seen these just really stressed-out parents and really annoyed babies because they're scratching—they're scratching their eyes, they're just red all over, they can't sleep, they wake up in the middle of the night because they're itchy. We need to do whatever we can to make them as comfortable as possible, because that's really no way to live.

MD Magazine: Absolutely. And it's such an important marker to treat for—the quality of life in these patients, especially considering the role of the parents in it. And looking on the other side of the roles in this care, obviously there's a whole network of caregivers involved in each food allergy patient, but if we can focus in more particularly on the primary care physician role: what is what is their responsibility in responding to a potential allergy? Are they often the first ones to diagnose or see the early signs of this?

Block: They are, a lot of times, the ones that first get alerted. And so being on the lookout for the signs, obviously, of an allergic reaction. A lot of times, especially with like milk, for instance, that can be a tricky one with babies, because baby spit up. And so primary care providers really need to be on alert for 'Is this just normal baby spit-up? Or is this a GI problem, where it could be a reflex issue? Or could it be a food allergy? Or could it be a combination of all 3?

And so they need to be on alert for how to recognize what a food allergy looks like, and what the symptoms of a food allergy are. And for babies, that could be spitting up. Obviously, it can be kind of the telltale signs of hives or trouble breathing, the acute reactions. Most of the time, the majority of the time, a food-allergic reaction is going to happen within the first 2 hours of ingesting the food. So, if a primary care physician is getting a story from a family, and the kid ate breakfast at 8 AM, and then pukes at 11:30 or 12, right before lunch, you kind of scratch your head about, was that really a food allergic reaction to breakfast? Because the timing doesn't really fit. Over 90% of the reactions are going to happen within the first 2 hours of ingesting the food, and the majority of those reactions are going to happen within the first 20 minutes.

So, really knowing those statistics and knowing whether or not it's a food allergy, if it's something that I need to worry about, is something that I need to refer. I would encourage people I would encourage primary care physicians to not take too much on.. They've got enough going on, they've got enough patient to worry about to diagnose food allergies. I would not encourage that—I encourage allergists to diagnose food allergies, not primary care physicians, especially when it comes to testing.

I told you before that one of my pet peeves really is a parent saying 'Can I just get a full panel done?' And I feel like sometimes primary care physicians will get panels done, and they might not include some foods, or they might include too many foods. And on the bad side of that is including foods that the kids already eating. If a kid is already eating oatmeal with almond milk and a little bit of peanut butter every single day for breakfast, you don't need to test for oat, almond, or peanut. Because even if it comes back positive, it doesn't matter. The kid's not allergic if the kid's eating it and not having a reaction on a daily basis.

And so you don't want to test for that. It's just going to cause more anxiety and confusion in the parents, because they're going to possibly want to start eliminating foods from the kid's diet. And that's exactly the opposite of what we want to do. We always want to try to encourage people to safely eat the foods that they can eat, not avoid foods that they can eat.

MD Magazine: Now moving on a little bit more to, I guess maybe the telling signs, or maybe not the immediate follow up to a food allergy diagnosis. In terms of the most common morbid conditions that we see with allergy risk, can you lay out exactly what would indicate allergy risk in any of these presenting conditions in pediatric patients?

Block: So the atopic march is the way that a lot of food allergy kids start, but not all of them obviously. The atopic march typically starts with eczema or atopic dermatitis. It can start as early as a couple weeks old, and it can start later, like around age 1. There's a wide range of when eczema starts. But the thought is that you kind of march through these different disorders. So it can start with eczema, then somebody develops food allergies, then they move on to develop asthma. And then they move on to develop allergic rhinitis.

Food allergies, most of them are diagnosed at a younger age—like you discover them as you're introducing different foods. But we also are seeing brand new food allergies later in life with adults that have been eating these foods and now randomly are getting these food allergies. And we are kind of really mystified about why that's happening in the new the newly-onset adult allergies.

But going back to the allergic march and testing for kids and everything: our theory is that if you are able to control at any point along the way, you might be able to prevent the next step from happening. So if eczema is super in-control, maybe we can prevent the food allergies from happening. If we don't have any food allergies to deal with, maybe there won't be as much of a an issue with asthma later on. The asthma is something that a lot of times is outgrown, and a lot of times it's not. It's a lifetime thing. Same with allergic rhinitis—it can kind of come and go. Both asthma and allergic rhinitis are very environmentally determined things.

So a lot of people can move from location to location. And in some locations they can have issues, and in other locations they don't. So it can really kind of fluctuate throughout a person's life—versus food allergies. Food allergies are pretty steady, if you have a food allergy and you haven't outgrown it. We haven't really talked that much about outgrowing food allergies, and that's because it doesn't happen super, super often. The 2 most common foods to outgrow the allergy is in the milk and egg. We think around 80% of kids will outgrow their milk and egg allergy, versus only about 20% of kids with a peanut allergy will outgrow their peanut allergy.

We think that tree nuts are around the same, like 20% to 25% of people will outgrow it. And shellfish might be even less than that. We don't have really great data. But it seems like if you have a peanut, tree nut, or shellfish allergy, you're more likely to not outgrow those allergies, unfortunately. But we don't have any data to say who's going to outgrow their allergy or why they're outgrowing their allergy, or if there's anything we can do to force their bodies to outgrow it. One of the thoughts is possibly, if you do therapy—which we're going to talk about in a little bit—if you do therapy at a really young age, is it possible to kind of force somebody's body to outgrow an allergy, instead of just treating the allergy?

So there's a lot of research going on. But we really don't know who's going to outgrow or what we can tell people to do. So from that perspective, there's really not much I can tell primary care physicians about what to tell people, if you already have an allergy what you can do to really get rid of it, other than find somebody to go through your options about therapy and how to treat it in different ways to manage food allergies.

MD Magazine: That's a pretty exciting preamble for our discussion on treatment later. It's going to be pretty forward-looking in terms of both current options, where we can eventually get to, and what the capabilities are. I'm excited for that. But maybe to wrap up this this chat on diagnosis, touching on all the points that we've talked about now: what is our current screening method? And does it vary? Do we stick to a strict protocol, or are there dividends and factors that may alter it patient-by-patient?

Block: So the 2 most common screening methods for food allergies is the skin test and the blood test. When they say the blood test, I'm talking about IgE levels and specific IgE levels to certain foods. There are other blood tests out there. Some of them are not commercially available, and some of them are commercially available, but they're just not proven to do anything.

So I would highly recommend that no one gets any IgG testing. It has not been proven to help diagnose food allergies, and it's just not a proven test. Don't do things that you know aren't going to give you any useful information. So for food allergies, I would highly encourage no one to get IgG testing. But regarding IgE testing and skin testing, they're both pretty nice screening tests, to guide us, to let us know whether it's safe to do a food challenge, or to be able to introduce a food into somebody's diet.

I've talked to different primary care doctors, and some of them feel comfortable ordering these tests, and some of them don't. Some of them don't have the capabilities of doing skin tests. And so that has to be done in an allergist's office. My big thing is to never order a test that you don't know what you're going to do with the result of. So, like I've said numerous times now, don't order a test for a food that somebody's already eating. There's really no point. If you know somebody who's not allergic to it, don't order that test. There's really no point. You're not going to do anything with that result.

But for foods that you do think that they are possibly allergic to, figure out what exactly you're going to do after you get that result. Are you going to be able to offer them some other form of treatment? Because now, avoidance is not the only option. And I can understand years ago, when a primary care physician wanted to do the test to be able to say, 'Yeah, the allergist is pretty much going to tell you to avoid this, they're not going to tell you to do anything differently. So just avoid the food.' Now, that's not the case. Now we've got treatment options.

And so if you're going to do a test, make sure you have a plan about what you're going to do with those results afterwards, like being able to refer to an allergist that can do therapy, like me over at National Allergy Center. Or don't even go toward ordering the test, and just refer out to an allergist that can get the patient those options.

So I'm not telling primary care doctors what to do or what not to do, other than don't do IgG testing. I think that there's places that feel comfortable doing the skin test and the blood test, but you really have to know how to interpret them. That takes a lot of finesse. That takes a lot of experience to know what numbers are positive, what numbers, because everybody's individual. And even though on the bloodwork, it might pop up as bold, just because it's bold and put the lab says that it's flagged as positive, doesn't necessarily mean it's an allergy. The blood test and the skin test, even if they're positive, does not necessarily mean that somebody is actually clinically allergic. It's just a guide to let us know what the probability is if somebody eats the food, if they would have an allergic reaction to it.

So that's really important for everybody to understand, because patients and doctors alike really love to order a test and have an answer. And blood tests and skin tests are not that test. You're not able to order that test and have an automatic answer. The food challenge is the only gold standard for actually testing to say 'Do you have a food allergy or not?' So it really depends on the primary care physicians comfort level. I would say majority of them don't want to deal with it, they don't have experience with it, and they don't have time to do it.

And so I would just recommend that if you are in that boat, to refer to somebody with a lot of experience, that knows how to diagnose, that has tons of experience with looking at all of the tests, and knows all the positive predictive values and everything that can go into it. And they also have options about doing therapy and doing food challenges and everything that kind of goes along with diagnosing the food allergy.

MD Magazine: Well, that's great. And I think that really puts a nice clean bow on the first 2 of our chats here: cause and prevention, and diagnosis. And it kind of sets up the table too, for our talk on treatment, coming up now. Whitney, before we get to that, is there anything else you'd want to add on these topics?

Block: I don't think so. If anybody has any questions, they're more than welcome to reach out to me.

MD Magazine: Yeah, there you go. That's great. We'll set that up too, as part of the cast. But for now, that'll be the end of this segment on our three-part chat on food allergy care. Whitney, thanks again for taking part DocTalk podcast. And thank you to all of our listeners for tuning in. Be sure to check out parts 1 and 3, on cause and prevention, and treatment. And for the latest in food allergy news, be sure to head to For now, I'm Kevin Kunzmann, and thanks for listening.

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