People of IPR
Thu September 12, 2013
Rethinking Childhood Food Allergies
There has been a change in thinking about childhood food allergies.
Kids often outgrow allergies to wheat, eggs, soy and cows milk.
For some time now, parents have been told it’s best to delay introducing babies to new foods such as eggs or peanut butter. But researchers now think such a delay may not have a significant impact on whether a child develops food allergies.
The American Academy of Allergy Asthma and Immunology has updated its guidelines and the new thinking is that there is no clear benefit to delaying introduction of these foods. In fact, there may be a benefit to introducing those foods early.
The new thinking comes as food allergies are on the rise. Peanut allergies have doubled over the last 15 years, from about 1 percent of American kids to 2 percent, and there are several theories as to why that is happening.
The American College of Allergy, Asthma and Immunology reports that about 5 percent of children under five years old have at least one food allergy.
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MEGHNA CHAKRABARTI, HOST:
It's HERE AND NOW.
A committee of experts from the American Academy of Allergy Asthma and Immunology has new guidelines aimed at preventing childhood allergies to foods, including eggs, milk, soy, wheat, fish, shellfish, tree nuts and peanuts. And that could change when parents start introducing these foods to their young children.
NPR's Allison Aubrey joins us to discuss the guidelines. And, Allison, one of the allergies parents fear most is peanut allergies, which have doubled over the past 15 years, from one to two percent of all kids in the country. Do scientists know why this allergy is on the rise?
ALLISON AUBREY, BYLINE: There's no unifying consensus as to why they're on the rise. Researchers have at least three theories. One involves vitamin D. There are a few studies linking vitamin D deficiencies to food allergies. And increasingly, scientists have pointed to something called the hygiene hypothesis. Have you heard of that?
CHAKRABARTI: Mm-hmm. Yeah.
AUBREY: This is this idea that our environment has become so clean that children no longer get exposed to as many serious infections. And as a result, our immune systems get busy fending off what should be harmless things such as peanuts or fish, you know, sort of mistaking them as invaders.
And the third theory really goes to the timing of introducing foods into babies' diets. Currently, there's a lot of research into this, looking at how whether holding off introducing the foods that are most likely to cause allergic reactions is of any benefit.
CHAKRABARTI: What's the new thinking on that timing question then?
AUBREY: Well, the thinking has changed quite a bit. Ten years ago, there was a lot of suggestion that perhaps it was best to delay the introduction of some of these foods. But a committee of the American Academy of Allergy Asthma and Immunology has actually issued revised recommendations this year that reflect a shift. I mean, the new thinking is that delaying introduction of the highly allergenic foods may actually increase the risk of food allergies. So there's a move towards introducing allergenic foods earlier.
I interviewed Dr. David Fleischer. He's an allergist at National Jewish Health in Denver, and he helped write the new guidelines. He explained to me that there are several new studies. In one, researchers introduced infants to a milk-based formula at different ages.
(SOUNDBITE OF INTERVIEW)
DR. DAVID FLEISCHER: And if they gave it before, two weeks of age, versus giving it later on, after, you know, about three, four months of age, it did seem to prevent milk allergy.
AUBREY: So that's really a suggestion that there's a benefit to this early introduction. But Dr. Fleischer says there's still a lot that's not known. For instance, allergists are waiting on data from big studies that are evaluating the introduction of peanut protein at six months of age as opposed to later ages to see if this makes a difference.
CHAKRABARTI: You know, imagine a lot of parents hearing this, sort of thinking, this is pretty big news that there may be no benefit to delaying introduction.
AUBREY: Right. Well, I have to say, what Dr. Fleischer is quick to point out is that there are certain instances or situations when consultation with an allergist is recommended before introducing these allergenic foods. And this would include if a baby has severe eczema or has had early allergic responses to food. But otherwise, there seems to be a nudge towards, yes, earlier introduction.
CHAKRABARTI: OK. So what about for all those who already have food allergies? What do we know about the likelihood that they may outgrow them?
AUBREY: Well, many kids do outgrow allergies to milk, soy and some of the other common allergies, such as egg and wheat. Unfortunately, the numbers are lower when we start talking about peanuts and tree nuts. For peanuts, it's about 20 to 25 percent of kids. Dr. Fleischer says it's about 10 percent for tree nuts. And it's also not that common to outgrow shellfish allergies.
So to figure out if a kid or a teen is outgrowing an allergy, allergists do these blood tests called serum IgE tests to see if levels of the IgE antibodies are coming down, and this can be an indicator of whether a kid is outgrowing the allergy. If it looks like they are, then allergists can do food challenge tests, and this is where the kid comes into a doctor's office setting. They feed the food the patient is - the kid is allergic to, and then they see if the kid tolerates it.
So it's kind of a process, and in, you know, unfortunately, lots of cases, the allergy is not outgrown. I myself have had a lifelong allergy to shellfish, and, you know, it's a bummer, but it's not going to go away, you know, not on its own.
CHAKRABARTI: Yeah. So given that, and for the fact that a lot of people may not want to wait to have their kids outgrow food allergy, is there any hope that some sort of treatment might be on the horizon?
AUBREY: Well, you know, there is some hope. There's a lot of research into what's called immunotherapy as a way to desensitize people to the foods that they're allergic to. And the idea here is to introduce tiny amounts of a food, in some instances, you know, just a few milligrams, say, of a peanut protein. You give it repeatedly over a set period of time, and gradually the hope is that the patient starts to build up some kind of tolerance.
Dr. Fleischer says that, you know, some studies show that oral immunotherapy can be really effective, but some patients do get reactions. And then there are also instances where people seem to be gaining a tolerance, but then after the treatment stops, they lose the tolerance. So it's still really early days here.
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FLEISCHER: So while parents and people in practice are really wanting to see these therapies to be approved, we need more time before it's something that's really going to be used more mainstream.
AUBREY: So, you know, you get the sense that, yes, there's an excitement here, but there's also a sense that this is not ready for prime time yet.
CHAKRABARTI: NPR's food and health correspondent Allison Aubrey with some new thinking on food allergies in children. Allison, thank you so much.
AUBREY: Thank you, Meghna.
CHAKRABARTI: And Allison will be back next week to answer your questions about food, health and nutrition. Send us your questions at hereandnow.org or facebook.com/hereandnow. Transcript provided by NPR, Copyright NPR.