Are Allergies to Blame?
St. Joseph Medical Hospital
I sat with the children yesterday while they were playing in camp and it’s interesting that I’m here because when I ask the little kids how many of them actually have food allergies, probably about 80% of them raised their hand. Then I asked them how many of them ate the foods they were allergic to and half of them raised their hands. It’s actually an interesting insight and what I’ll talk about and kind of what things you guys have been told about as parents.
I am not the allergist that believes that everything we’re dealing with is solely due to allergies. The objectives are to look at the role of allergic disease in atopic dermatitis, to talk about the hygiene hypothesis a little bit because again it’s in the lay press a lot. Talk about the role of food allergy and eczema, is there really a role, is there not, is it overblown more than people think?
There’s this little girl, on every single slide and the reason she’s on there is for two reasons. I do this as a professional passion. I did this as a professional passion before I had children. I’m still doing this now because my daughter, because of the way God works, has really bad eczema and was diagnosed when I was a fellow at National Jewish and actually diagnosed by some of the world’s experts in eczema. Because of that, any advice I would give, the way I look at this disease, the way I interact with families comes from not just what I do all day long with what I do for a living but what I go home to at night. The bottom line is if there was a simple solution or if there was something that was so straightforward that I could tell you to fix your kid, I would have done it a long time ago. I really would have and I think in all of our frustrations when we live with this day in and day out, we lose sight of the fact that really it is a complex disease and there’s not a simple answer for all of us and that again, if it were so simple, don’t think that I wouldn’t have figured it out way long ago.
If you look at my daughter, there’s a dog right there. We didn’t get rid of our dog. My daughter eats just about whatever she wants, and we go just about anywhere. If you look at her in the pictures, you’d never know she has eczema and that’s my message for you guys. I don’t want kids to know my kid has eczema not because I’m afraid of it but because it’s not something that ever influences who my child is.
The bottom line is it’s my fault because I’m an atopic person. Some people believe that our genetic makeup is what makes us more likely to develop atopic disease so even before we’re born, things that happen are what make your child more likely to have issues. Secondly, there are other people that feel that multiple effects after birth are what happens so in other words you take a genetically susceptible individual, you put them in the right position and then they get bad eczema. Is it a combination of both? The answer is probably yes.
What are allergies?
Just about everybody here as sat down with an allergist, been told they’ve been allergic to stuff but nobody can answer their question what an allergy actually is. In a general sense it just reflects immune dysfunction. In other words your immune system just gets all goofed up for some reason and it’s as simple as your immune system overreacting to something that it should normally just leave alone. So the grass outside, the ragweed around you, the dog that walks in front of you or even the food that you want to put in front of your child. It can include all these things and other immune stimulating substances. Now where it’s important to realize is anything theoretically can cause an allergy, even the most hypoallergenic formula, even water I’m sure, any sort of substance to your immune system doesn’t belong to itself. So the body has the potential to consider something an allergy although there are certain substances and things that are more allergic than others. In a general sense anything that doesn’t belong to you can be allergic. You can have atopic dermatitis without atopy and that’s what’s so funny about this disease. It’s called atopic dermatitis. It means allergic dermatitis in some way because that’s what atopy is and what we can see is there is a three-fold increase in allergic disease in most children over the past 30 years. We don’t know why exactly. I’ll give you some things that we’re thinking about, but allergic disease is on the rise for some reason.
Only about 3-6% of the population in the U.S. has a true IgE food allergy. That’s not that much. There’s some interesting data from probably about 10 years ago where we took big samples. This is out of the food allergy and anaphylaxis network data. 60% of the population in the United States, adult and children will change their diet because they think they’re allergic to something. That’s the standard population. This is not just our families here who are in this room but regular people completely change their diet because they’re allergic to something and that goes into not everything’s allergy. But explain to some parents in the room that onions make my eyes water and my nose run when I cut them. It doesn’t mean I’m allergic to them but again what’s allergy? I tell you when I go near ragweed, my eyes itch and run and my nose runs. There really is a difference in this process and it’s understanding what’s a really allergic process and what are things that can be irritating and making things worse for other reasons.
In young children and infants with moderate to severe eczema, most of the families here have a child with fairly moderate to severe disease, even out of those kids only 30-40% of those kids have a food that drives their eczema. So that means that 70% of the kids in this room probably don’t have a food that’s completely driving what makes their eczema worse and that’s important to remember. I don’t think any of us whether they’re dermatologists or allergists or I would hope the allergist wouldn’t blame every single food or what not on eczema and allergy but I guess they often do. The fact of the matter is only a small portion of them do. It’s important for a good allergist to sit there and tease out the stuff that’s okay and the stuff that’s not okay and move on with it and not tell you you’re allergic to everything under the sun.
In the adult sense this is a different disease process as you know, most adults do not have a food that’s the primary association with their eczema although they may have foods that are closely related or may have anaphylactic reactions to foods.
Allergies and the HygIene Hypothesis
Using my daughter as an example, is dirt good? I get asked this all the time. There’s a lot of literature about there about this idea of the hygiene hypothesis and again the idea of the hypothesis is we are seeing an increase in allergic disease because of the way we live. We no longer live out on the farm and have 16 cows around us and eat cow dung all day and eat dirt essentially. It really comes out of the westernization of our lives. If you look at other countries such as South America, Africa, some of these poorer countries, the incidence of allergic disease is a lot less than we see in Western countries and that would include northern climate countries such as Europe and the United States and even ones on the far southern ends like South Africa. These are studies that look at broad populations of thousands and thousand of people. Your children or you as individuals were going to be this way whether you liked it or not because of who you were in terms of genetics. The example I give to families is if you look at my daughter, she kind of looks like me. When I show you a picture of my wife, my wife is Scandinavian. As much as I’d want my daughter to look like my wife, she’ll never look like my wife regardless if I put contacts on her and dye her hair. Okay? She is going to be who she’s going to be and so this idea of let’s get a dog, let’s let our kid eat dirt, let’s let him roll around in dirt and then he won’t get as many allergies later in life and the food allergies will go away has no application to any of us.
If you feed your kid dirt you’re just going to make him poop dirt and that’s just about it. It won’t make things go away. In terms of prevalence, though, we look at this and again there is a tie-in, there’s a role for an allergist in the terms of the management of eczema because what ultimately happens is there is a prevalence of food allergy and other things in atopic diseases. So 35-40% of children with moderate to severe eczema have food allergies related to it and 6% of kids with asthma actually experience wheezing with food allergies.
Positive and Negative Allergy Tests
I don’t do that much allergy testing so no, you come to see me, you do not get 9,000 things on your back. It’s usually some form of some sort of extract of a certain concentration. These things are popped on your kid’s back and they scratch. Sometimes we use fresh food extracts depending on a particular food that we may be worried about because there are certain proteins that are not in commercial extracts. Then they’re usually applied by a prick puncture technique so that funny little scratch device or toothpicks. In general if allergists are doing interdermal testing to foods, it is contraindicated and none of us in the academic field would ever recommend that at this point and I’ll leave it at that. If your allergist has done that to you, that wasn’t a good thing. Nevertheless, the positive predictor factors.
These two things are probably the two most important pieces of information I want you guys to take home. Positive predictor factors, in other words the chance of that test telling you something that’s a true allergy is only 50% at best and in somebody with eczema that probably goes down to probably less than 25% because their skin is so reactive. So when you get allergy testing done and are told your kid has allergies to every single food in the world or everything around them, allergy is a systemic disease or something that happens to you right away and you see it in their nose and their eyes. They throw up or their lips swell or something happens. It’s not just because of what the test showed you. In other words, I tell my families if you want me to, I’ll make you allergic to whatever you want and I can do it and most allergists can. What’s more important is this piece of data, the negative predictor of accuracy. When you have a negative skin prick test, it’s almost 95% chance that it’s completely negative and that you don’t have a problem with it and you can move on with it. Now there’s a 5% chance it could be wrong, but in general what’s more important as allergists is what’s negative, not as what’s positive.
Nothing is solely based on either blood work or skin testing. In terms of food triggers, there is a paper published in the Journal of Pediatrics in 1985 that essentially took 100 kids with significant atopic dermatitis and essentially they gave these kids the foods and saw what happened. In the end what it came down to is in general about the top eight foods that we all keep talking about accounted for 85% of the culprit foods that drove eczema. And that was it. Of these other foods that people start bringing up, these unusual mammalian proteins, some in the other categories were just unusual foods. It was really rare that those foods caused problems so in general most kids and adults all fit up in one category.
When we talk about milk allergy we also talk about this is where sometimes the beef allergy comes into. Kids who are really milk allergic sometimes have problems with certain types of beef. And then when we look at egg, this is the raw egg issue and the cookie dough issue. The risk of reacting to a tree nut is 35% if you have a peanut allergy and then if you have a tree nut allergy, the risk of reacting to another tree nut is about 35-40% chance so there’s this cross-reactivity issue. So when I diagnose a kid with peanut or tree nut allergy, I end up just telling them they’re allergic to all of them because there’s a chance that something else is going to react and it’s just a chance issue and it’s a cross-contamination issue more than anything else. It’s not practical, you can’t eat this nut versus that one.
A lot of kids test positive for soy and a lot of times that’s just due to they’re grass allergic because remember soy is grass and grass is soy and legumes as well sometimes cause an issue. But it’s only less than 5% so it’s a really rare instance so when people bring up the fact that peanut’s a legume and soy shows up, it’s really a very small category of kids overall.
It all ends up usually being these essentially four food groups, peanuts, tree nuts, fish and shellfish. Again the risk of reacting to pecan is actually high if you’re sensitive to walnut and it’s because they share a common epitope which is the allergic antigen itself. If you look at pistachio and cashews, those two usually go together so if you look at your skin test and said wow, look how big my pistachio is, there’s probably a good chance your cashew is high as well. The risk of reacting to another fish is 50% whether that’s a fish in the ocean versus a fish out of a lake. A fish in some ways is the same. It’s usually the albumin that is in the fish that causes most people’s problems. The risk of reacting to another form of shellfish is 75% and this is a misconception from the old days. No, you’re not allergic to radio contrast dye if you have to have a CAT scan or procedure if you’re shellfish allergic. There are other reasons that you have issues but it’s not because you’re allergic to shellfish so all those little old ladies who were told after you CAT scan you had a bad reaction, stop eating crab because it’s bad for you, you don’t need to do that at all. This is where the confusions come from.
There is data that got this whole thing started about why all food and eczema go together. There were some really interesting studies that were done by testing and challenging and again. Some of these are over periods of time in the early ‘90s and the ‘70s where they took kids with eczema and they essentially eliminated these foods from their diet. And it did show that in some kids their skin got better but these were kids that were documented by challenges and these went back to the idea that these were moderate to severe kids. A lot of the major culprits were milk and egg, and if you remember milk and egg allergy, roughly about 80% of children will outgrow that allergy by the time they’re five anyway so that there’s a link but there’s not a cause or effect and it wasn’t the milk that made your kid’s eczema worse all the time. It’s just that these two things exist together. If you can eat a food without any reaction, for example swelling of your tongue, tightness of throat, etc., or again a major flare of your eczema, it’s really unlikely that food’s causing a problem because the bottom line is eczema gets worse on its own no matter what you do.
There were some families that brought up that two or three days after my kid ate some food, their eczema got worse. The connection’s not there. When we do our challenges, we expect the challenge to happen and the reaction happen within the first six hours. If it’s not worse right away then it’s not going to be worse later and something that happens two weeks later probably is not related to a specific food.
Did the eczema come first or the food allergy come first or did the food allergy make eczema come or did eczema make the food allergy come? The answer is most kids will develop their eczema as the first sign that they’re an allergic child. What unfortunately happens is you can see this parallel. The food allergy stuff all exists in the first year of life. It’s all eczema and food allergies but what happens over time and the big question is what happens over time because most of the kids here are older than five. All these numbers start to go down. The food allergy stuff drops pretty quickly first and that reflects that idea that most kids with egg and milk allergy have it go away. The kids that are left over behind are mostly peanut and tree nut allergic kids.
The eczema itself in general starts to get better as these kids get older than five. If they have recalcitrant disease that stays around with them, then it’s true it stays around with them but it’s not being driven by the foods that they’re eating. It’s the disease itself that’s continuing on but what immediately happens is you start to see the addition of asthma and actually the addition of hay fever start to come out right at the time the food allergy stuff disappears. Eczema in many ways is just the first hint that allergic disease is around. It’s not a cause and effect but it is the march and there were some studies that tried to look at can we make hay fever and asthma less likely to happen if we fix kids’ eczema early on? And that was based on the idea that these children sensitize to things in the environment through their skin. We haven’t seen the rest of the data yet but that’s the proposition with some studies that are going on right now.
The IgE levels in the blood get bigger and higher over time in general because again, these people get more allergic over time. Is there a link between eczema and asthma? The answer is yes, in some ways. There were studies that came out in the late ‘90s and again in 2000 by my mentor, Donald Leung, that showed that if a kid really had fairly bad eczema before age five, there was an 80% chance that they had some form of asthma. Doesn’t mean the worst asthma in the world, it could be as simple as exercise-induced asthma, but it really gave you the hint that these were going to be allergic people later on in life. And that’s really what we see in this room, it’s what we see just around in general.
What can we do? You can look at my Scandinavian wife and look at my poor daughter who looks like me and I feel horrible. My son has no eczema but has longer hair than my daughter. She’s eating whatever she wants.
There is an important role for both dermatologists and allergists, but the issue is as much as I’m a pediatric allergist doing allergy, my role is somewhat an afterthought. I help manage skin disease, I help manage the afterthought diseases which potentially are the food allergies, the asthma and the rhinitis that come later. I have been very aggressive in terms of addressing food allergy and asthma issues because my hope is to stop the progression of the other diseases if they all come out. But there’s a role for both of us to work together and again there may be new therapies that address the food allergy issues which are an aside from the eczema. But they may inevitably influence the atopic march which may influence their asthma and their eczema later in life. In terms of alternative therapies, again most families in my mind attempt to use alternative therapies to address allergic issues. There are some therapies with some promise but again none of them have been well studied and well regulated that I would say are safe for your child. I use my child as a gold standard. There’s nothing safe enough that I can promise myself that my daughter won’t get cancer later on from it. In my practice and again the area I’m in and across the country, we do see super infections with staph and other types of bacteria, but other types of bacterial and organisms cause allergies and cause things to happen more. Again these have never really been played out as much as people will tell you that you’ve got a horrible cannibal yeast infection and that’s the sole cause of everything. This is in the food allergy realm that’s become very controversial and it’s a reminder to all of you that as long as you have a true diagnosed food allergy, eating these small amounts of foods that desensitize yourself or your child have never been shown to be proven. There are four studies going on around the country right now looking at oral desensitization protocols for peanuts and tree nuts and egg, but they’re still in the phase 1 trials and I’ll tell you, in those trials a lot of kids anaphylax to eggs by accident during the trials under well-controlled settings. We’re a long way before we can figure it out. What it reflects is probably there are some kids who probably can’t eat stuff in baked goods. It doesn’t make things worse but the reason we always talk about avoiding foods is what we know right now from the data is it does potentially make these allergies worse and this is why you’ve been asked to avoid certain foods. Thank you.