Peanut Allergies In Kids Are Finally On The Decline

FLORA LICHTMAN: I’m Flora Lichtman, and you’re listening to Science Friday.

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Today in the pod, big news in the food allergy world.

SHARON CHINTHRAJAH: This gives us a little bit of hope that we are making a dent in food allergy.

FLORA LICHTMAN: Some welcome news– a study in the journal Pediatrics found that peanut allergies in babies and little kids are on the decline. And this drop correlates with a guidance change from the National Institute of Allergy and Infectious Diseases. In 2017, they started recommending that we expose children to peanuts early and often.

And since that recommendation, the prevalence of peanut allergies has dropped significantly. And that’s a huge shift because for many years, peanut allergies were on the rise. Here to churn through the findings is Dr. Sharon Chinthrajah, a physician specializing in allergy and immunology at the Sean N. Parker Center at Stanford University. Sharon, welcome to Science Friday.

SHARON CHINTHRAJAH: Thank you, Flora. I’m so excited to be with you today.

FLORA LICHTMAN: So what did the study find exactly?

SHARON CHINTHRAJAH: So what the study looked at is the rate of food allergy prevalence, how many people have food allergies, by studying the electronic medical records before the guidelines were changed and then immediately after the guidelines were changed, and then a little bit post that period as well. And by looking at that, they found that the rates of diagnosing food allergy has dropped after the guidelines were published.

So that’s super exciting, because the guidelines were based on NIH-funded research. And that’s very solid data and evidence, that if we introduce peanut early in the diet for infants, for babies, that we can actually prevent the development of peanut allergy. And that was a huge study that led to the guideline changes. And so what it says is that doctors are doing a good job. Families are doing a great job, following those guidelines or knowing about those guidelines, how to feed their babies, what to feed their babies, to make a difference, to prevent food allergies.

FLORA LICHTMAN: Tell me a little bit more about this. Where did this idea of microdosing peanuts to babies come from?

SHARON CHINTHRAJAH: Oh, it’s such a great story, Flora. This is why I always tell my kids and students to be very curious. So Gideon Lack, who’s the last senior author of the LEAP study, this study that I was talking to you about, and other researchers noticed that Jewish babies in Israel didn’t have food allergies. But Jewish babies in London and UK, where he was located, had food allergies, had peanut allergies.

So even though they shared similar genetic backgrounds and probably cultural backgrounds, there was something different about the environment that was showing more peanut allergy in London than in Israel. And when he went to go visit colleagues and friends there, what he noticed is that families were feeding babies peanut bamba. And now, back in the day, nobody would know what peanut bamba is. But now, because of that–

FLORA LICHTMAN: Every parent knows what peanut bamba is now.

SHARON CHINTHRAJAH: Exactly, exactly. And there’s even different flavors, right?

FLORA LICHTMAN: These are like– they’re like Cheetos, but they’re covered in peanut butter, basically.

SHARON CHINTHRAJAH: You’re exactly correct.

FLORA LICHTMAN: And they’re Israeli, right?

SHARON CHINTHRAJAH: Yes, yes. And now, there’s all different types of brands. And the beauty of it is, is that it melts in your mouth. And so, for babies, it’s not a choking hazard. So that’s the key piece there. And so babies were holding on to these little puffs, and it was dissolving in their mouth. And they were getting good oral and gut exposure to peanut proteins early in life. And that is so important. Turns out that that exposure early in life, in that critical window, when you start to introduce foods into the diet is so important.

Because guess what? 70% of your immune system lines your gastrointestinal tract, lines your gut. And so you are training your gut that peanut is fine. Peanut is OK. Peanut is harmless. Introducing peanut as early as four months of age and keeping it in the diet, it reduced the risk of developing food allergies at the age of five by 80%.

FLORA LICHTMAN: Wow, 80%. That’s amazing.

SHARON CHINTHRAJAH: Huge.

FLORA LICHTMAN: Yeah, huge.

SHARON CHINTHRAJAH: Just by this simple change in dietary introduction.

FLORA LICHTMAN: Hmm. Can I ask you a question? Why are peanuts such a trigger for the immune system? What is it about the humble peanut?

SHARON CHINTHRAJAH: Oh, my gosh. This is a million dollar question. The immune system is tricky. It’s meant to be a defense against harmful things in the environment. And so when we’re talking about food allergy, we’re talking about IgE antibodies. This is different than the types of antibodies we use to fight off bacteria and infections.

And it’s an age-old system really meant to protect us against parasites. And the IgE antibody recognizes proteins in the environment. So if you have seasonal allergies, it’s recognizing proteins in pollens. So if you have food allergies, it’s recognizing proteins in food.

And the many reasons, I think, we’re becoming more allergic as a society– and there’s environmental influences and genetic influences there. But the way the body and the immune system sees the food proteins is really important. And it turns out that if you eat a lot of peanut in your household– Mom, Dad, sister, Grandma– that you can find peanut protein in the dust in your household.

FLORA LICHTMAN: Is it just very durable? Is that the idea? It holds up in the environment?

SHARON CHINTHRAJAH: It holds up. And guess what? So that dust can be exposed to your skin. And if you have eczema, a different type of allergic disorder, your skin barrier is not perfect. It’s leaky. And so if your immune system sees peanut protein more commonly through this leaky skin, it actually trains your immune system to develop an allergy.

FLORA LICHTMAN: Huh.

SHARON CHINTHRAJAH: So it’s even more important that we train it via the gut.

FLORA LICHTMAN: So your immune system is looking for these proteins. I mean, is that why eggs are also problematic? Because they’re protein-rich?

SHARON CHINTHRAJAH: Yes, yes. So not all food proteins are equal. Egg, I think, is probably one of the first foods that are introduced and very common in the household because of baked products. Eggs is a good source of protein. Milk is another one that is common early in life.

But what’s really interesting is that in the over 10 years that I’ve been really studying food allergy, different allergens are popping up because our society is more interested in enriching protein in our diet and healthy proteins, like tree nuts and peanuts, which is actually a legume. And so we’re starting to see different types of allergens early in life as triggers for food allergy.

FLORA LICHTMAN: Like almond butter or cashews or walnuts or something because people–

SHARON CHINTHRAJAH: Yes.

FLORA LICHTMAN: –are using these more in food.

SHARON CHINTHRAJAH: For sure, cashew and walnut are becoming more prevalent than 10 years ago. And the initial guidelines changed in 2017. And then the NIH and expert panels put together a recommendation to introduce peanut early into the diet. It changed in 2021 to liberalize that all foods. You should have a diverse diet early in life, not just peanuts, tree nuts. And that’s really important. This new study published in Pediatrics, also funded by taxpayer dollars and the NIH, shows that we’ve blunted the rise of food allergy.

FLORA LICHTMAN: Right, it wasn’t just peanuts, right? It was other foods, too.

SHARON CHINTHRAJAH: It was other foods, too. And but it’s still there. And so early introduction is not enough for everybody, but it is now flattening the curve. Prior to the guideline changes, it kept on rising. The number of food allergy diagnoses was on the rise. And so, at least, we’ve blunted that. And we need to look and see, have we blunted that for all of these other foods?

FLORA LICHTMAN: Do we understand why some people are still susceptible?

SHARON CHINTHRAJAH: That is a great question. We know that food allergy occurs in babies and children that have already this allergic immune system. And they have other allergic diseases like eczema or atopic dermatitis. And we know that babies can show signs of allergic inflammation, even in the first weeks of life, so that there’s a skewing of their immune system because they have drier skin or eczematous skin.

And so the question really, then, is, how early should we be introducing foods into the diet? And how? And we need to figure out ways how we can do the introduction of foods earlier than six months, earlier than four months, in a very safe way.

FLORA LICHTMAN: We’ve covered other large epidemiological studies on the show in the past, and we know how hard it is to actually have a study where we’re like, OK, case closed. And I know in this study, they looked at electronic health records, not actually at what the kids ate. And we know that the timing lines up so that it suggests that it is linked to these new recommendations. But do we know for sure? Is there more work to be done?

SHARON CHINTHRAJAH: You hit it on the nail. One of the limitations of this study, Flora, is that it looks at electronic health records. The gold standard of diagnosis is a food challenge, where we’re actually introducing the food and watching for an allergic reaction, which is often done in the allergist’s office to manage allergic reactions in case.

But I think this gives us a little bit of hope that we are making a dent in food allergy. We’re working on better diagnosis other than the food challenge, and now that there are treatment options available. So we’re getting there. Food allergy is a chronic disease once you have it. We don’t yet have a cure. And but we have more treatment options available so that people don’t have to suffer with it, compared to earlier days.

FLORA LICHTMAN: Dr. Sharon Chinthrajah is a physician specializing in allergy and immunology at the Sean N. Parker Center at Stanford University. Sharon, thanks for joining me.

SHARON CHINTHRAJAH: Thanks so much for having me, Flora. It was my pleasure.

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FLORA LICHTMAN: Today’s episode was produced by Rasha Aridi. I’m Flora Lichtman. Thanks for listening.