The Doctor Trying To Solve The Mystery Of Food Allergies Nearly 15 million Americans have a moderate to severe food allergy. In kids, the rate is one in 13. Kari Nadeau, who studies food allergies at Stanford, is currently testing a technique to desensitize children who have multiple severe allergies to foods like nuts, soy, milk, wheat and shellfish.
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The Doctor Trying To Solve The Mystery Of Food Allergies

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The Doctor Trying To Solve The Mystery Of Food Allergies

The Doctor Trying To Solve The Mystery Of Food Allergies

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This is FRESH AIR. No one is certain why food allergies are on the rise. But now, one of every 13 children has a food allergy. Nuts, soy, milk, egg, wheat and shellfish are some of the foods that most commonly set off allergic reactions. In some cases, the reaction can be so severe that it results in the throat swelling up and closing, leading to death. For a child with a severe food allergy, every meal that isn't made under appropriate supervision can be hazardous. And since so much social life is based around food, family life becomes restricted.

My guest, Dr. Kari Nadeau, is one of the scientists at the forefront of food allergy research. She directs the Stanford Alliance for Food Allergy Research, SAFAR, at Stanford University School of Medicine. She's an associate professor of allergies and immunology at the school and the Lucille Packard Children's Hospital. Dr. Nadeau is currently conducting a clinical trial testing a technique for desensitizing children with multiple severe food allergies.

Dr. Kari Nadeau, welcome to FRESH AIR. Before we talk specifically about the research you're doing, 90 percent of food allergies are caused by cow's milk, egg, soy, wheat, peanuts, tree nuts, shellfish and fish. Why? Like, do those foods have something in common?

DR. KARI NADEAU: That's a great question. We're still trying to understand those answers. I think that we know that at certain points in life, cow's milk is more prevalent in children with food allergies, compared to peanut or shellfish or fish, for example. But that all those foods, they don't have one protein in common. So we think that there's something about the foods and about how they're being delivered that people are becoming allergic to them. And importantly, is that 30 percent of people with food allergies can actually be allergic to more than one of those foods. So we don't exactly know why those foods, and that research is still underway.

GROSS: What do you mean when you say how they're being delivered might be a factor?

NADEAU: Yeah. We're looking at whether or not other dietary components and whether or not environmental factors - for example, different environmental exposures like pollution and tobacco and whether or not they're being delivered orally or through breast milk, or with other environmental features associated with them. We don't know the answers to how they're being delivered in the gut and why, to some children, they're seen as toxins, as it were, just seen as allergens that their body responds to, versus in other children, they're fine and they're used as nutrients. So we don't understand what flips the switch between a food allergen versus a food nutrient in children that are taking those foods early in life.

GROSS: What happens in a severe allergic reaction to food that makes it life-threatening?

NADEAU: In some cases, what happens is the food allergen is ingested and the body sees it as foreign. And it sees it as foreign as if it were an allergen that could cause a severe issue in the body. And so what happens is this huge chemical response occurs within minutes and you can have powerful chemicals released by the body that can hurt the body. And those chemicals are called histamine and there are many other chemicals as well.

But the majority of those chemicals lead to swelling and that swelling can occur internally in the body as well as externally and it can cause a lot of itching. So people get hives. But they can also get swelling internally to - unfortunately in some cases - these are rare but it can happen - it can lead to swelling internally of the throat and in the lungs, and respiratory issues are some of the major ones that we worry about in a severe reaction.

And these reactions can occur within minutes. And so one has to be ready very quickly with an EpiPen to be given right away if someone has any respiratory distress.

GROSS: And an EpiPen is a shot of - it's a little pen injector that has epinephrine, which is a form of adrenaline, right?

NADEAU: Right. Exactly. It's very simply that.

GROSS: You direct the Stanford Alliance for Food Allergy Research at Stanford University. So you're doing state-of-the-art research on food allergies, and one of the approaches you're investigating is an approach that's been used for a long time to desensitize people with allergies to like grasses or pollen or cat dander. Would you describe this approach to food?

NADEAU: Sure. What we are doing is what one would call something that has been done over the past 100 years with pollens and with other allergens like bee sting allergies as well as to animals. So what you do is you give the person back the item that they're allergic to. In the case of foods, there are many different types of therapies being tested right now by many groups around the country as well as the world.

But what it usually involves is a small amount, let's say specks of the food. Very small amounts of the food that you can barely see in a dish. And then over time you increase that dose ever so slightly. And we want to make sure that the patient can tolerate the dose well and this is safe. And then every two weeks you come back into a clinic and you increase that dose.

And this would all be done in a research setting with a very well-trained team of individuals that are ready to help the patient for any type of reaction. So this type of therapy over time is called desensitization. And by the end of a number of months to years, one can get up to, if, again, they succeed and comply with the study, one can get up to about a serving's worth of food.

GROSS: Now, one of the things that you're doing that's very cutting-edge is that you're trying to desensitize individuals to several foods at a time. So instead of just, OK, I'm going to desensitize you to corn and then we'll desensitize you to wheat and then if you do well with that we'll desensitize you to cow's milk - you're taking maybe three things that the person - three foods the person is allergic to and trying to give them trace elements and then tiny bits more of each of those foods at the same time.

NADEAU: That's right. People have been doing work in monotherapy around the country as well as around the world...

GROSS: So monotherapy is exposing to one food at a time.

NADEAU: Exactly. So people - peanut therapy was being given at University of Arkansas, University of North Carolina, and then milk and egg was being looked at in Mount Sinai. And milk was being looked at at Johns Hopkins. And so a lot of exciting data was coming out and still is.

But for me, I had one patient come up to me and just say, you know, I have so many allergies, there's no way I could do the monotherapy in my lifetime. It would take 10 to 20 years. And there are many people with multiple food allergies; 30 percent of people with food allergies have more than one food allergy. And so I thought about it a little bit more and then I called - I'll never forget stopping on a highway. It really bothered me because I kept on pondering this and I was driving to my aunt's house in New Hampshire.

And so I stopped along the road and I called my colleague Wes Burks and I had a conversation with him. And I said do you think it's possible - do you think that one could actually simultaneously give multiple foods in oral immunotherapy? And he also said, OK, let me think about it. I'll get back to you. And then let's really design this trial so that, again, safety is paramount. And how could we do this best?

So I thought, OK, if we're going to give multi maybe for some people we should also give this anti-IGE therapy. And that's when I called Dale Umetsu and talked to him.

GROSS: And what's anti-IGE therapy?

NADEAU: Anti-IGE is a therapy that was approved for asthma and it's used to actually try to inhibit one pathway of the allergic response. And so by giving it, it's kind of a cover that helps the immune system be able to take the food at higher doses much faster in this type of oral immunotherapy study. And so people were able to get to their higher dose of food compared to people who didn't take the anti-IGE. And they were able to do that much faster.

GROSS: My guest is Dr. Kari Nadeau. She directs the Stanford Alliance for Food Allergy Research. We'll talk more after a break. This is FRESH AIR.


GROSS: Nearly one in 10 preschoolers has a food allergy and the rate of children with food allergies has more than doubled over the past decade. So what are some of the theories about why the number of children with food allergies is growing?

NADEAU: We have been looking at why this increase in incidence and prevalence has occurred across the United States. There are approximately 15 million Americans with food allergy. One in 13 under the age of 18 has a food allergy diagnosis. And not only are we seeing an incidence in prevalence but we're also seeing an increase in emergency room visits. For example, there's about 90,000 per year that were recently published.

And the costs are increasing as well. About 500 million is spent per year on the cost for food allergy ER visits and for all those other medical needs. So with that in mind, people are working hard at trying to understand the causes. We think right now that it's probably multi-factorial. There's no easy answer, as you would probably expect.

Studies funded by FARE and NIH have shown so far that there's probably a gene environment interaction so that there's something about inheriting your allergies. If a person who has an allergic family, their child might have a food allergy, for example. But that's not necessarily always the case. There are families in which they have no allergies in the family and for the first time they have a child and that child has food allergy.

There also seem to be interactions with the environment. We're doing research through the Children's Environment Health Centers and NIH about the role of tobacco and pollution as well as diet. And recent studies have shown that perhaps a more Mediterranean-type diet, less trans-fatty sort of fast-foods type diet might actually help in decreasing the risk of food allergies. But that's really over the interlay of genetic factors as well.

So it's an excellent question. More research needs to occur to understand why food allergies are increasing in our population and then really to try to find out how to better diagnose them so that we can prevent them and to perhaps, if they are in our control, change behaviors.

GROSS: So when you're talking about genetics being an issue for food allergies or it possibly being an issue, do you mean the genes passed on by the parents? Or do you mean some kind of change in the genetic structure of the child after the child is born?

NADEAU: Right...

GROSS: Because there's a lot of research into that now about how certain, you know, toxins in the air or toxins in food, toxins you inhale, can perhaps make slight modifications of the genes that have major repercussions.

NADEAU: That's exactly right. There are genes that we inherit from our family and our grandparents and those are genes that are ingrained in the sequence and that's where we inherit certain things like maybe perhaps our height, our color of our eyes, for example. And then there are things like atopy or allergies that can be passed from the family. And that is ingrained in the genes.

However, there are also what you're mentioning - how the environment can affect the genes and how the environment can modify the genes itself. And that field is called epigenetics. And what we're finding is through work, not only of our own, but also through other groups sponsored by the NIH and other organizations, that pollution and tobacco smoke and diet can affect the genes themselves on a chemical basis.

And that can be inherited down through to the children as well as the grandchildren. So there's a combination of genes as well as this epigenetic or how the environment can affect the genes. And we know that those two things play an important role in any one individual. For example, we've published data now out of Stanford in which, through people that received immunotherapy for grass pollens, for example, that their genes changed over time during the therapy so that they became modified to a non-allergic state. Which is very exciting because what you would then take the next step in thinking is that perhaps the children of the people that received immunotherapy might be able to have those same non-allergic type genes passed on to them. So we don't know that yet. We still have to do research.

GROSS: Dr. Nadeau, I wish you good luck with your research and thank you for sharing some of your research with us. Much appreciated.

NADEAU: Thank you. Thank you so much for the opportunity. It's wonderful to talk to you.

GROSS: Dr. Kari Nadeau directs the Stanford Alliance for Food Allergy Research at the Stanford University School of Medicine. To find out more about her research, you can go to our website,, where you'll find a link to her lab's website and a link to a recent New York Times magazine article about her. That's, where you can also download podcasts of our show.

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