Research Tries To Lessen Food Allergies' Bite

Matthew Fenton, branch chief, Asthma, Allergy, and Inflammation Branch, National Institute of Allergy and Infectious Diseases, Bethesda, Md.

Jennifer Schneider Chafen, MD, health policy fellow, Veterans Affairs Palo Alto Healthcare System Center for Primary Care and Outcomes Research, Stanford University, Stanford, Calif.

Scott H. Sicherer, MD, co-author of books including Understanding and Managing Your Child's Food Allergies and The Complete Peanut Allergy Handbook; professor of pediatrics, clinician and clinical researcher in the Jaffe Food Allergy Institute, Mount Sinai School of Medicine, New York, N.Y.

A recent study in the Journal of the American Medical Association found flaws in how food allergies — abnormal responses to foods triggered by the body's immune system — are diagnosed. New guidelines on dealing with food allergies are scheduled for publication this fall.

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IRA FLATOW, host:

You're listening to SCIENCE FRIDAY from NPR. I'm Ira Flatow. You know, for many people, for most of us, I dare say, a peanut butter sandwich on a whole wheat bread and a glass of milk, mmm, it sounds like a pretty good lunch. Or maybe a bowl of Pad Thai, maybe with some tofu in there for good measure.

But if you have food allergies, these lunches could make you sick, and in some cases an allergic person's reaction to these dishes could kill you. But it can be hard to get a handle on just who actually has food allergies and who doesn't, in some cases because people misrepresent their own symptoms and in some cases because diagnostic tests may be inconclusive or used incorrectly.

There's an article published recently in the Journal of the American Medical Association, and it concluded that tests commonly used to help diagnose food allergies may be improperly used or misinterpreted, and some people with an intolerance for a food, let's say a lactose intolerance, may incorrectly be classified as having a food allergy.

So for the rest of the hour, we're going to be talking about food allergies, what we know about them, how they're diagnosed, what can be done to help people faced with the prospect of living with a food allergy.

And if you have a food allergy, and you want to get in on the conversation, our number is 1-800-989-8255, 1-800-989-TALK. Tell us how you've lived with it, how it was discovered, maybe how it was misdiagnosed. You can also tweet us @scifri, @-S-C-I-F-R-I. Or you can go to our Web page at sciencefriday.com and join the discussion with other folks talking about food allergies.

Let me introduce my guests. Matthew Fenton is the branch chief of the Asthma, Allergy, and Inflammation Branch at the National Institute of Allergy and Infectious Diseases. That's part of NIH in Bethesda. He joins us from our Washington studios. Welcome to the program.

Dr. MATTHEW FENTON (National Institute of Allergy and Infectious Diseases): Thanks, Ira, it's a pleasure to be here.

FLATOW: You're welcome. Jennifer Schneider Chafen is the health policy fellow, Veterans Affairs Palo Alto Healthcare System, and is at the Center for Primary Care and Outcomes Research at Stanford University. She's also an internist and author - and one of the authors of that JAMA review article. She joins us by phone from France. Bonjour. Bonsoir.

Dr. JENNIFER SCHNEIDER CHAFEN (Stanford University): Bonsoir, Ira, thank you very much.

FLATOW: Thank you. You're welcome. And Scott H. Sicherer is a co-author of several books, including "Understanding and Managing Your Child's Food Allergies" and "The Complete Peanut Allergy Handbook." He's also a professor of pediatrics and a clinician and clinical researcher in the Jaffe Food Allergy Institute. That's at Mount Sinai School of Medicine right here in New York. Welcome to SCIENCE FRIDAY.

Dr. SCOTT H. SICHERER (Mount Sinai School of Medicine): Thank you very much. Thanks for the invitation.

FLATOW: You're welcome. Jennifer, the article you co-authored in JAMA, it reviewed the existing literature and found that there were holes in what we know and what we don't know about diagnosing and treating allergies. What were some of the holes?

Dr. CHAFEN: That's a great question, Ira. We are - our review read over 12,000 articles in search of trying to figure out most - the best information on prevalence, diagnoses and management of food allergies, and what we discovered, the biggest hole is that there's not an agreed-upon definition of what constitutes a food allergy.

FLATOW: There isn't?

Dr. CHAFEN: No, it turns out there's not, and that makes a comprehensive review of the literature very difficult to come up with, you know, best practices about how best to diagnose and manage food allergies.

FLATOW: Matthew Fenton, why, if I go to my doctor - is this saying that, in looking at all these patient visits to doctors, a lot of them may have been misdiagnosed?

Dr. FENTON: Yeah, I think there's quite a bit of evidence out there in the scientific literature and clinical literature to suggest that there is over-diagnosis and over-self-reporting by patients who go to their physician with a complaint of a food-related disorder.

FLATOW: Scott, you're a practicing allergist. Is this surprising to you?

Dr. SICHERER: It's an unfair question to weigh because I'd have to say that there was nothing about this that was a surprise to me. But it was a very valuable review of the available literature, which was actually done for the purpose of having a background in order for experts - and Matthew can talk more about this - going forward to use the available data to provide eventually practitioners with evidence-based information to be able to do more in terms of diagnosis and management of food allergy.

FLATOW: How would you define, how would you define food allergy?

Dr. SICHERER: Well, you know, I think we were a little bit talking apples and oranges for a second there because I think what Jennifer is pointing out is that when you're reviewing the literature, there potentially are several disorders that are being described in different articles, and different authors might use slightly different definitions of food allergy.

But for the most part, what these allergist experts have been looking at over the years is defining food allergies and adverse immune response to the proteins, typically proteins in foods.

And so this differentiates it from a lot of other adverse effects that could happen from foods, for example toxic reactions. There are actually chemicals in spoiled dark-meat fish that can cause allergy-like symptoms, that's the scombroid fish poisoning.

There are pharmacologic agents in foods, like caffeine that could make some people jittery. And then there's intolerances. For example, some people can't digest the sugar that's in milk lactose, for example, and can have gastrointestinal symptoms from that.

All of those examples are not food allergies. They're different because they don't involve an immune response to the food proteins.

FLATOW: Jennifer, would you agree?

Dr. CHAFEN: Yes, I would agree. I think my comment about there not being an agreed-upon definition is just that when we were searching the medical literature for food allergies, the very diverse literature, in fact food allergy itself, when you type it into the medical subject heading context, is not a term. So really to try to get at what we're talking about with an immune response to food was a very challenging prospect for us.

FLATOW: Matthew Fenton, the NIH commissioned that report. Why? Is it trying to update guidelines for doctors and what they should look for or what a food allergy is?

Dr. FENTON: Back in 2007, the NIH, or specifically the NIAID, was approached by a professional medical society and a patient advocacy group who said that they felt that there was not only a need for updated guidelines for physicians and health care professionals but also a need to reach across medical specialties and make sure that we were reaching out to all physicians, not just the allergy community, and make sure that there was a consistent message for both defining and diagnosing and managing food allergies. And that's what spurred our project.

FLATOW: Scott, many years ago, I remember when I was a teenager and was allergic to almost everything, and I knew that because I went into the doctor's office and he gave me a skin-scratch test for a hundred different things, covered my whole body with little fussy - little lumps. Is that the right way to test for food allergies these days?

Dr. SICHERER: So one of the points that came out in the JAMA article is that there's essentially not one single diagnostic test that tells you a black/white yes/no answer - this is something you're allergic to, this is something you'll be able to eat without a problem.

And in fact, the reason that we see these allergies most of the - there are many, actually, different manifestations of food allergy, but the ones that we typically talk about are more the sudden reactions, the acute reactions, things like anaphylaxis or, you know, severe reactions that come on soon after eating it.

The immune mechanism there is that the body is making an antibody called IGE that's able to detect the food, and there are ways of measuring that. And the skin test that you just talked about is one way of measuring it.

The problem is, is that many of us can make IGE antibodies to a particular food, or for that matter even environmental allergens and other allergens in the environment, and maybe not have symptoms when we're exposed to it.

One study would suggest that if I took someone out of the mall and, you know, stopped them from shopping and did an allergy test to peanut, about eight percent would test positive. But more than 98, 99 percent of those people would have been able to eat peanut without a problem.

What we've learned over the years is that the stronger the immune response, the more likely it is that the positive test really does indicate an allergy. So for example, the size of that skin test, or in a blood test the level of IGE to peanut in this particular example, the higher it is, the bigger it is, the more likely that there really is a clinical reaction. However, a test alone is not the way that we diagnose a food allergy.

FLATOW: 1-800-989-8255. Let's go to Hillary(ph) in Denver. Hi, Hillary.

HILLARY (Caller): Hello, thank you for taking my call.

FLATOW: Go ahead.

HILLARY: I have a two-year-old who is a very allergic little boy, and we actually just saw our allergist yesterday. So he has peanuts, eggs, milk and now sesame seed. And sesame, I guess my question is: Is there any research being done to help come up with a test - like you said, you could scratch for a thousand things, but, you know, they're saying it's kind of trial and error, and as the parent of an infant, it's very scary to try a food like hummus, that I tried, only to watch your child blow up in hives and start throwing up and...

FLATOW: Right. So your allergist said the best way to do this is to give it a little bit and see what happens.

HILLARY: No, no, he's just saying...

FLATOW: He said trial and error.

HILLARY: You know, by trial and error he's just saying that there's really no test - you can't test for everything out there at the moment. You'd have to take a gallon of blood and test for everything. So unfortunately, you know, we've learned sort of trial and error some of the things he's allergic to, like peanuts.

So it's just interesting. It would be interesting if there was research trying to help identify ways to come up with foods that you might be allergic to, you just don't know yet.

FLATOW: All right, Hillary, we'll see if we can get you an answer. Thanks for calling.

Dr. SICHERER: I would address that, sort of in a general way, because I don't want to make a specific diagnostic comment for one patient. But this is actually a very good example of what you brought out when you said you were tested to a hundred things. It's easy to do a test, but it's harder to interpret it. And ultimately, the most important test in allergy is the history. And so, in this particular case, I would guess that the child hadn't tried sesame yet and the parent would say, well, gee, you know, do I have to worry about this or that, or there might be some preconceived notions about some foods that are higher risks than others for causing an allergic reaction would lead to a test.

If you're tested to something you're already eating, and that food didn't bother you, well, that test shouldn't have been done in the first place. And it goes back to my example of the person who's grabbed out of the mall and tested for peanut for no reason and, you know, has an eight percent chance of being positive. A lot of these tests pick up cross-reactions. Foods have some proteins in common, and sesame is a really classic one for that. It's not unusual to see a positive test in someone who has other food allergies or has even pollen allergies.

And so, again, we would be looking at the extent of the tests, but ultimately, when the time comes - and it may not be the right time for this young child - but when the time comes, we actually have a very definitive test for food allergy and that's called the oral food challenge or feeding test - when under medical supervision, not tried at home, we give a gradually increasing amount of the food to find out if there are symptoms. And if we see symptoms, obviously, we stop feeding, end there and say, well, it looks, you know, your child is allergic. But if we're able to feed the whole serving of the food, then that's great indication...

FLATOW: Right.

Dr. SICHERER: ...that there's nothing to worry about. So it is a very definitive test.

FLATOW: And so, in another words, the definitive test is a - your child or you go to the doctor's office and he sits - he or she sits there and watches...

Dr. SICHERER: That's what we do...

FLATOW: ...as you get a little piece of that food?

Dr. SICHERER: That's what we do every day over in our practice.

FLATOW: And that would - what about people who come in and say, you know, I - my allergy seems to have gone away or I seem to have gotten this later in life. Is that a common thing or they just ignored it all those times?

Dr. SICHERER: There's two angles there. And there good news about most childhood food allergies is that the common allergies in childhood, which are milk, egg, wheat, soy, peanut, tree nut, fish and shellfish -many of them go away during childhood and that includes milk, egg, wheat and soy allergies.

Now, peanuts, tree nut, fish and shellfish allergies tend to be long-lived and it's harder to outgrow them. But the good news even there is that we have found from studies that one out of five young children with peanut allergy actually does outgrow that by school age. So, you know, we do want to relook at that. And you're right on the flipside, which is it's possible to develop an allergy at any time, at any age to almost any food. And we have some idea as to why that might happen, but you're right that it does.

FLATOW: We're talking about allergies this hour on SCIENCE FRIDAY from NPR. I'm Ira Flatow. Let's talk about how much we know, Matthew, about what makes certain foods allergic. Scott was just talking about there might be some ideas. Why are people just sensitive to certain foods like nuts or eggs but not, say, pork or carrots or the other kinds of things?

Dr. FENTON: Well, unfortunately, there's a whole host of reasons and very different ones that can lead to this huge variety of sensitivities to food. And ultimately, most foods have the potential to be allergic and to cause allergic reactions. The ones that Scott mentioned are the most common. But if we look across the world, there's a variety of additional foods that are also major problems.

Ultimately, the causes come from a number of factors. There's genetics and family history, early exposures, perhaps even as early as in utero exposures, early life exposures, whether or not a child is breastfed, whether or not that child gets solid food introduced early or late. And these all can combine to add up to the final cumulative risk that that child will incur.

FLATOW: Mm-hmm. 1-800-989-8255. Let's go to Melissa(ph) in San Antonio. Hi, Melissa.

MELISSA (Caller): Hi, Ira.

FLATOW: Hi, there.

MELISSA: It's a joy to be on the show.

FLATOW: Thank you.

MELISSA: I'm a frequent listener and first-time contributor.

FLATOW: Oh, welcome.

MELISSA: I have a completely different experience from Hillary's - well, maybe not completely. My daughter is 27 years old. She was diagnosed by a patch test early, with a very serious allergy to tree nuts. And we managed that and she managed - she learned to manage that to the best of her ability. And then she decided she wanted to become a Peace Corps volunteer in Africa. And first of all, the medical screening was overwhelming. And she was told many times this isn't going to happen. We can't be sure that you will be safe. And then, I don't really completely understand why it worked out. But anyway, she's been there and it - of course, Peace Corps service presents a variety of food challenges.

FLATOW: Right.

MELISSA: She has managed those. She's still alive. She keeps her EpiPen with her. So I kind of want to say, all of you people out there with really serious food allergies, that there are adventures waiting for you and that good things can happen.

FLATOW: All right. Thanks, Melissa, for sharing that with us.

MELISSA: Thank you.

FLATOW: 1-800-989-8255. Is there a frontier in food allergy research someplace, things you'd love to have?

Dr. FENTON: Oh, absolutely. I think one of the most promising frontiers for research is the development of immunotherapies that can be used to treat food allergies. Or, the gold or the brass ring at the end is to prevent them from occurring in the first place, to develop a treatment for very young children prior to their development of allergic sensitivity that we can use to block the eventual formation of clinical food allergy.

FLATOW: You know, when I was getting all my tests done years ago, they used to have allergy shots, and these were pollen, grasses and weeds, and little tiny bits of it given to me in a shot. Can you do that with food? Can I make somebody resistant who has a peanut allergy, by gradually giving tiny pieces of peanut, increasing that?

Dr. SICHERER: Well, the story on that is that in the '80s, that was tried in giving injections of peanut just the way you said it. But unfortunately, there were many side effects from giving that. In effect, it caused anaphylaxis, severe allergic reactions from the injections themselves. So subsequent to that, the approach has been to say, well, we know that there is a strategy to have exposure to what you're allergic to to try to reeducate the immune system not to have adverse reactions. However, obviously, there has to be a - either a different route or a different method of doing it.

Actually, the NIAID has funded a consortium of food allergy research that's looking at a variety of strategies to try to more effectively treat food allergy. One of them that's being looked at is what we call oral immunotherapy and its relative, sublingual immunotherapy. This is giving gradually increasing amounts - again, this is not something to try at home - but gradually increasing amounts of what the person is allergic to into the mouth or under the tongue for a period before being swallowed, with the idea that it may be able to raise the threshold of the amount of food that would be able to be given before there's a reaction or maybe even create tolerance or cure a food allergy after months and maybe years of that kind of exposure.

FLATOW: We have to break. We'll come back and talk lots more about food allergies, so stay with us. We'll be right back.

(Soundbite of music)

FLATOW: You're listening to SCIENCE FRIDAY from NPR. I'm Ira Flatow. We're talking this hour about food allergies. If you'd like to join us, give us a call: 800-989-8255. Or send us a tweet: @scifri, @-S-C-I-F-R-I or go to sciencefriday.com and join the online discussion there with folks who are talking about their allergies.

My guests are Matthew Fenton, Jennifer Schneider and Scott H. Sicherer. And our number, as I say, 800-989-8255. Jennifer, let's talk about other holes that you found in the study about what we know about allergies. Isn't one of the standard treatments for allergies often eliminating all the food from your diet and putting some of it back in and see what happens?

Dr. CHAFEN: That's right. In - our study did not look at frequency of treatment management strategies, but we were surprised, though, that there, only one study qualified for inclusion criteria in our study that looked at elimination diet, which is essentially saying if you have an allergy to cow's milk, don't drink cow's milk.

FLATOW: And you're saying there's - there was only one study that backed that theory up?

Dr. CHAFEN: Well, I wouldn't even say that it backed up the theory. I would say there's only one study that met our - we had very strict inclusion and exclusion criteria as to what was a quality study to make it into our meta-analysis. And I - I'd love to hear Scott's thoughts on why he may think that's true.

Dr. SICHERER: Well, I - thank you for asking. I think that it's just such a self-evident truth that we know from everyday experience, that if someone who's - we've, you know, clearly shown as allergic to something; if they try to eat the food, they have a reaction. So we would sound kind of bizarre to say, you know, we don't know if avoiding that food is a good idea or not, go ahead and eat it, and then have them react for, you know, another time. So I think the point is that there aren't studies about it, but on the other hand, probably one of the reasons is it's just so self-evident that avoiding the food that you're allergic to is the primary treatment.

I mean, our main hope, actually, is to create treatments that make it so that you can eat the food again. And I wanted to mention that one of the other very exciting treatment strategies that we're looking at is to alter the protein in a way that you could give it as immunotherapy, but maybe not trigger the allergic reaction. We're looking at that right now in a study that's part of this consortium I talked about before.

FLATOW: Mm-hmm.

Dr. SICHERER: This particular study is recruiting adults with peanut allergy at Johns Hopkins in Baltimore and also at Mount Sinai in New York - who have peanut allergy, to give them a modified peanut protein. The protein was essentially engineered to remove some of the areas that would trigger the IgE response in people who are already creating that IgE to peanuts, so that hopefully we would have a quote, unquote "safe shot" that would not trigger a reaction but would still reeducate the immune system, with time, as typical allergen immunotherapy for pollens does.

FLATOW: Are you looking for people for those studies? Because we always hear that it's always tough finding people.

Dr. SICHERER: Hint, hint, yes, we are.

(Soundbite of laughter)

FLATOW: And they're being conducted at Mount Sinai and Johns Hopkins?

Dr. SICHERER: This particular study, yes.

FLATOW: Okay. There's a hint. Let me ask you this question about - once people discover that they have a food allergy - okay, I have a food allergy - what do you tell them to do? How do they - how is it best to manage it?

Dr. SICHERER: Well, you know, the therapy for food allergy, as I mentioned, is to avoid it - and that sounds so easy - okay, you're allergic to peanut or you're allergic to milk, don't eat it. But it's really a huge lifestyle change. As one of the callers said before, you know, there are adventures ahead. My idea is you should have, you know, a full and normal life.

If you have a food allergy, you just need to not eat what you're allergic to. But - and even that is a little bit easier said than done. You have to learn how to read product labels. When you're buying things in the supermarket, that also means extra time. It means asking a million questions when you would go to a restaurant. It means worrying about all of these issues for every time we eat food - vacations, travel, social events, trick-or-treating. And you could imagine, for children, it affects school and camp.

FLATOW: Yeah.

Dr. SICHERER: So there's a lot of education that goes into, you know, how do you avoid the food, day to day. There's a huge impact on quality of life, again, which has been shown with our studies, to be effective for people who are living with this. But with education and with knowledge - and I'm going to put it in another plug that the NIAID actually supported a study to create educational materials to help with educating families about food allergies, which is so important, and also understanding how to use medication.

You mentioned - epinephrine was mentioned before. Self-injectible epinephrine is prescribed to be carried by people who have life-threatening food allergies. So the big package deal there is that we have to teach people all of these things.

FLATOW: Well, how do you know if you've been misdiagnosed with food allergy? How do you know whether it's you have lactose intolerance, you have some other kind of gastrointestinal problem but it's not a food allergy and that you've been told that it is?

Dr. SICHERER: Well, it sounds - it's going to sound like I'm just pushing my specialty - but a board-certified allergist would be the person to speak with about symptoms of - in medicine, these days, I think you would - should start out talking to your primary care doctor about the symptoms.

Again, the history is the main thing. But if it sounds like the symptoms are more classical for true allergy as opposed to intolerance or some other adverse effect I mentioned at the top of the program, then referral to a board-certified allergist for the appropriate testing and ultimately the, you know, potentially definitive feeding test.

FLATOW: Yeah. Jennifer Chafen, as an internist, not as an author of this paper, are these finding's going to change how you deal with your patients?

Dr. CHAFEN: Yes, they will. And I would actually back up Scott on that, to say that I see a lot of people with general complaints. And I think in the past I maybe sent some tests and may have misinterpreted some of the tests in the setting of the clinical history. But really depending a little bit more on our food allergy experts I think would be very useful.

FLATOW: Mm-hmm. 1-800-989-8255 is our number. Let's see if we can get a question or two more in here. Why, Matthew, are we seeing the numbers of people reporting food allergies just skyrocketing in recent years? Do you think there - are these real? Are they due to misdiagnosis, misreporting, or what?

Dr. FENTON: I think it's a combination of those factors. As you probably know, there's been a general and dramatic increase in allergies to airborne allergens like pollen over the past two decades. And we think that food allergies may be part of that general rise in allergic diseases that we've seen. It's very difficult to get accurate numbers on that because of the possibility of overdiagnosis. The other factor that contributes, and we saw a similar thing with asthma years ago, was as the public is better educated and more aware of the disease and the symptoms, they bring it to their doctor more early on, they bring their children for testing very early, so there actually is better health care assessment and more diagnoses that get made. So overall the prevalence and the incidence looks like they're on the rise as well.

FLATOW: Let's see if we can go to Barbara in Albion, Michigan. Hi, Barbara.

BARBARA (Caller): Hello.

FLATOW: Hi there.

BARBARA: Thank you, Ira.

FLATOW: You're welcome.

BARBARA: As the mother of a child with allergies, I'm wondering why we are not more aware in this country and place warnings on labels. For example, if something has been prepared in a factory where peanuts is utilized, in the United States, to my knowledge, there is nothing on the labels, whereas in the U.K. and in Canada they do have something on the label specifically stating this is not a peanut-safe food or this is not safe for tree nuts, et cetera. Thank you.

FLATOW: You're welcome.

Dr. SICHERER: I could take that.

FLATOW: Go ahead, Scott.

Dr. SICHERER: So the Food Allergen Labeling and Consumer Protection Act has now required for the past few years that foods be labeled with the major allergens in plain English terms. So, again, milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish have to be on the label if they're a known ingredient.

What she is discussing is the potential for cross contact and unintended ingredient in a food. Currently, that type of labeling, what we call advisory labeling, is indeed not regulated and it's not required. So manufacturers do use labeling like that, they may say may contain peanut, in a facility with peanut, et cetera, but it's just not something that they're required to do.

We did a study looking at whether individuals were following those labels or not, and we found that over the past several years people with food allergies are not listening to those warnings as much as they did several years before, probably because they're getting inundated with them. We did another study showing that it's getting to be more than half of the products, practically, that are the convenience foods, are having those advisory labels on them and people start to wonder whether it's real or not.

But the studies that we've done looking at assays of the foods do show that we're looking at about seven percent for peanut, when it says may contain peanut, and also that it doesn't matter what kind of warning statement - "in a facility with" or "may contain" - that doesn't tell you the risk. But she's absolutely right, that this is a huge burden and I know that the FDA is looking into what can be done to improve it.

FLATOW: Matthew, what other suggestions do you have for guidelines for doctors? What do doctors need to know that they're not doing now?

Dr. FENTON: Well, I think the issue is one of consistency across various medical specialties. I mean, Jennifer mentioned this before in her comments, that she may now look at the symptoms she sees in her patients a little differently than she might have prior to her work on this project. And one of the biggest goals of our clinical guidelines for the diagnosis and management of food allergy is to provide a common definition for food allergy that we heard at the very beginning of the show and a common set of diagnostic criteria that can be used. Our guidelines in the work that RAM Corporation has done has extensively looked at the utility of various diagnostic approaches, to really separate out the ones that are the most valuable.

So our guidelines will recommend to physicians that they use the most valuable of these tests in association with a good patient history, and as Scott mentioned, ultimately the oral food challenge, to come up with a very strong diagnosis, and we're going to make these recommendations strongly throughout the clinical community.

FLATOW: Would it be a good idea if you were diagnosed with an allergy 30, 40, 50 years ago, to go back and see maybe that you've been misdiagnosed and missing out all these years?

Dr. FENTON: One thing that studies have shown throughout the years is that there are lot more people who say they have a food allergy than after all of the evaluations are done actually have it. Now, that's not to say that food allergy is not a prevalent thing. It's just that there are more people walking around who are avoiding a food that maybe they don't need to avoid.

It's actually a critical time in food allergy, I think, because the CDC came out with this study indicating that 3.9 percent of the children have food allergies, which they indicate is an 18 percent increase in the last 10 years. We did a study of peanut allergy in - this was a telephone survey, so it has limitations. However, we used the same exact methodology in 1997 - one in 250 children were reported to have peanut allergy. We repeated that in 2002. The number jumped one in 20 - one in 125. And then we repeated it again just recently and had one in 70. So we're looking now at 1.4 percent of children being reported with peanut allergy in our survey study, which, while it has limitations, matches the percentage that countries like the UK, Canada and Australia are also reporting in school age children.

So what's going on here? I mean, we obviously need to find better ways to prevent, to diagnose, to treat. And it's one of the amazing things that Jennifer's JAMA study points out, or review points out, is that although we have a lot of knowledge on all of these topics, we definitely need more and, you know, we need to do more research to be able to solve this problem.

FLATOW: Well, I want to thank all of you for taking time to be with us. I just want to remind everybody that I'm Ira Flatow and this is SCIENCE FRIDAY from NPR.

And Matthew Fenton at the National Institute of Allergy and Infectious Diseases; Jennifer Schneider Chafen from the - at the Center for Primary Care and Outcomes Research at Stanford University; and Scott H. Sicherer of the Jaffe Food Allergy Institute at Mount Sinai School of Medicine, thank you all for taking time to be with us.

Dr. SICHERER: Thank you.

Dr. FENTON: Thank you.

Dr. CHAFEN: Bye, Ira.

FLATOW: Have a good weekend. You're welcome.

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