Allergies to food are becoming more common and more severe in modern times. We talk with members of the Food Allergy Science Initiative to discuss why that is, as well as the scientific work being done right now that may one day lead to a cure for food allergies. This Pulsar podcast is brought to you by #MOSatHome. We ask questions submitted by listeners, so if you have a question you'd like us to ask an expert, send it to us at sciencequestions@mos.org.

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ERIC: From the Museum of Science in Boston, this is Pulsar, a podcast where we seek answers to the most thought-provoking questions we hear in our exhibit halls and in our virtual programs. In the past few years, our Current Science and Technology team has produced presentations that cover the latest research into food allergies, and after one of these shows, a visitor asked: will we ever be able to cure them? That seems ambitious, but work is being done on that very front. My guest today is Dr. Christine Olsen, a radiation oncologist at the Massachusetts General Hospital Cancer Center right across the river from the Museum of Science. She's also one of the founders and the executive director of the Food Allergy Science Initiative. We're also joined by Dr. Dominic Beal, an immunologist and scientific advisor at the Food Allergy Science Initiative. Dr. Olsen and Dr. Beal, thanks so much for being here.

CHRISTINE: Oh, well, thank you for having us. We're excited to talk to you today.

DOMINIC: Yeah, thanks for inviting us. This is kind of exciting.

ERIC: So why don't we start with: biologically, what is a food allergy? What's going on in the body?

CHRISTINE: Food allergy is basically a reaction of the immune system to a food substance that our body thinks is noxious. Noxious meaning harmful or poisonous. And it's to the point where even a small, tiny amount of food could actually cause an allergic reaction. And this reaction can range from mild to life threatening. You could have just simply some itching and hives that go away, or it can progress to where you have swelling of the tongue, vomiting, diarrhea. And even to the point where you have difficulty breathing and blood pressure at a point where it's a life threatening reaction called anaphylaxis.

ERIC: So our immune system kind of going into overdrive unnecessarily.

CHRISTINE: That is a great way to explain it, yes.

DOMINIC: One of the problems, I think, is that food allergy is classically thought to be a mistake of the immune system. It's mistargeted, and it's reacting to something harmless, instead of doing what it's supposed to do: reacting in something dangerous, like a bacterium, or a virus. That way of thinking focuses your attention on a narrow aspect of the disease, which is the immune response. And even though we've known about allergies for a very long time, we still don't know a lot about some of these really fundamental questions such as: how do you develop sensitivity? And why do you develop sensitivity? So at FASI, the Food Allergy Science Initiative, we're trying to understand food allergy from first principles, not necessarily influenced by any existing preconceived notions about this disease. Most diseases are abnormal versions of some normal biological process that is, perhaps, a defense mechanism. So we need to understand what this normal counterpart to allergy is, so that we can then understand the disease and be able to develop rational therapeutic approaches.

ERIC: And I imagine that if we want to understand this reaction at a basic level, we want to think about why humans evolved the ability to have an allergic reaction in the first place.

CHRISTINE: FASI's Chief Scientific Officer, Ruslan Medzhitov out of Yale, recently published a paper on this and talked about food allergy being part of a broader defense system that we call food quality control. So that includes smell, taste, chemical sensing in the gut, and it helps us avoid eating things that might be harmful. Many plants, for example, contain substances that are deliberately noxious as defense mechanisms to prevent them from being eaten because plants want to survive as well. And so you had to be able to detect these substances and be able to avoid them. In the case of food allergies, what we think about for nutrients, is when you eat something, you take it in, the body evaluates it in the guts. And you have to think about the gut as really being the only system in the body that is exposed to the outside world. Your skin has a barrier, you know, your lungs are more of an air exchange, gas exchange. And so this was a defense mechanism set up for the body for knowing when to absorb nutrients, were they safe to absorb. And if they weren't, you had to get rid of them, and get rid of them by diarrhea, vomiting, and try to expel them from the body. And then if you did get exposed to this, and it was bad, you needed to remember it. And so that's where the immune system and nervous system were talking together and then saying, okay, I ate this thing. It was bad for me. So the circuits in the brain say, okay, it goes to the hippocampus and says, remember that food, then it goes to the amygdala, where the fight or flight is and says, fear this food, you know. So if you see it, get away from it. It's a mechanism of survival. And what we think is that you know, this has been exaggerated and some kids that have food allergies. And that's what we're trying to understand is why.

ERIC: Are we seeing food allergies get more common? I've seen a little bit of like, headlines of that, is that actually there in the data?

CHRISTINE: In recent years, there's been a significant rise in food allergies. There's an estimated 89 million people in the US that have either a food intolerance or food allergy with about 32 million having clear food allergies, and that's nearly 10% of the population. And this is 10 times the prevalence it was 35 years ago. So not only is the prevalence of food allergies growing, but the severity of the symptoms are increasing as well.

ERIC: Do we know what's driving this increase? What's causing it?

DOMINIC: It can't be solely accounted for by genetic change. It's far too rapid. It's very likely that there's this environmental component, but we don't really understand what it is. We have some good ideas as to what it is. So we know that there's new components in our diet that have been introduced in the last hundred years or so. Things like pesticides, preservatives in food, household items like detergents, a lot of over the counter medications. Antibiotics, for example. Really, really important in medicine. But also we know, obviously, they kill bacteria. They're influencing the microbiome, they're influencing the gut, what are they also doing with regards to how our bodies sense nutrients? It's a big question.

ERIC: So we're seeing an increase in numbers, but it's still not universal. So do we know why some people develop food allergies, while others don't?

CHRISTINE: We think there's probably a genetic predisposition to it that allows you to be more susceptible to it than others. And it can also just be maybe in your environment, you have had more exposure to certain types of chemicals that have changed your microbiome and your guts that has made you more susceptible as well.

DOMINIC: There's also the idea of behavioral changes. There's a lot of changes recently, for example, about how early we expose children to different types of foods. So do we expose your children to peanuts very early? Or do you wait? Current thinking now is trying to expose them as early as possible, and that helps prevent allergies. But the thinking around that has changed quite a lot in the last few years.

ERIC: So what can we do about food allergies? Will we be able to find a cure?

CHRISTINE: I believe we will. I think there's different ways of looking at it. There's prevention. I think the early introduction that we talked about earlier will help with that. You know, when I think about food allergies, you have about 20% of kids that can outgrow them. And adults, you see that, you know, half of them actually getting it as an adult. So there's some type of dial that's making it turn on or off. When you think of tastes, you think of your mouth, you know, which has lots of taste receptors, but you also have them in the gut. And so the gut is kind of responsible for telling us whether something is safe or not. So we're looking at: what is sensing in the gut? And can we kind of turn that around? I think we will. But I think it's complicated, because there's different types of food allergies that develop different types of ways. And so it's really exploring it. What we've found in the past few years, just from the food quality control from how the gut and the brain talk to each other, how the microbiome is involved. And now what we're looking at a lot is the food chemistry as well, that will really help us kind of solve that. So it's like you're having a puzzle, when you have many pieces of the puzzle, you know, when you start to fill it in, and you don't necessarily have to fill every piece in to see what the image is going to look like. If you want to solve any disease, you need to understand the biology of disease. And you can look at any disease in history of medicine and realize that it's really the biology that makes the true discoveries to make the true cures.

ERIC: All right. Well, Dr. Olsen and Dr. Beal, thanks so much for being here.

DOMINIC: Thank you.

CHRISTINE: Thank you so much for having us, Eric, it was really a pleasure.

ERIC: Be sure to follow the Museum of Science on social media for the latest in Current Science and Technology, including updates on the work being done at the Food Allergy Science Initiative. Until next time, keep asking questions.

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