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What do we have here oh no no those are cashews.

So is this like a bowl full of death to you?

Yes, well cashews aren't as strong of a reaction for me but I am allergic to tree nuts.

It's not fun, it's not fun at all.

Hey smart people, Joe here.

I recently invited my friend wheezy waiter to come by and talk about food allergies.

Just one, they're not real cashews, they're stunt cashews.

Of course you should never trick a friend with the food that they're allergic to, but it's okay wheezy waiter and I are friends, and I'm a doctor.

These days most of us know someone with a food allergy, some food they have to avoid eating, or even coming into contact with in order to avoid a dangerous reaction or even death.

But why are people allergic to food?

And why are food allergies on the rise?

It's nuts.

Maybe I'm just getting old but it seems like food allergies are more common than they used to be.

Well we're not imagining things, scientific data backs that up.

The percentage of children with food allergy has definitely increased in recent years.

I'm allergic to all tree nuts so I'm allergic to walnuts, pine nuts, almonds, cashews, hazelnuts, macadamia nuts, pistachios - here in Texas - pecans everywhere.

Not pecans no pecans I always say pecans, but you've taught me it's pecans.

Yeah I play the right way yeah.

That stuff ends up in a lot of different foods, so I imagine you have to have accidentally encountered this stuff before.

I have accidentally encountered almost all those that I listed.

What happens is my mouth swells up, my throat swells up, I get hives, I get hives in my lungs, I can't breathe, horrible stomachache, and it lasts for three hours.

But I don't think about reading labels and that's a whole difference about how we navigate the world as things that I don't have to think about and you do.

And especially now it seems like the nuts are cropping up in everything like barbecue sauce or cocktails, like drinks now like to have walnut bitters in them.

To make matters even more confusing, adults can also become allergic to foods that they never had issues with as children.

I'm Emily Graslie I am the host and creator of the YouTube channel The Brain Scoop and I work for the Field Museum as their Chief Curiosity Correspondent.

So I saw on Twitter recently that you aren't getting along with certain kinds of nuts very well anymore.

Yeah I've never had a problem really with any sort of food you know, but otherwise never have had any sort of allergy whatsoever then a weird thing happened.

Why don't we try almond milk for the first time?

I never tried it.

The next morning just routine morning on my way to work I had my bowl of cereal, poured the almond milk on it and I got to work and I noticed that my nose was just dripping like a faucet, and I realized I was hot and itchy, and I noticed that I was just absolutely covered in full-body hives.

I just was like this is really weird.

Now a true food allergy is different from a food intolerance.

This is really important like if you're lactose intolerant and you can't digest cow's milk.

It can make you feel really sick Aches, pains and digestive troubles, that kind of stuff.

But if you're allergic to milk, it could kill you.

A true allergy is when your body's immune system has a reaction to the food on a molecular level.

It's your body treating food as a germ or an invader, which actually doesn't make sense.

Let's look at how this works.

Food is made up of lots of different molecular bits like the fats, carbohydrates, and proteins.

We're gonna focus in on the proteins - everything we eat has proteins and they come in a variety of shapes.

Our bodies usually digest food proteins down to their most basic units, but some food proteins don't get completely broken down and they escape into the body where they meet the immune system.

Now it's your immune system's job to recognize protein shapes that come from dangerous invaders - viruses, bacteria, things like that sneaking around your body.

But peanut butter should not cause this reaction.

This makes no sense.

Cobras, jellyfish, really big wasps.

Maybe.

But not deliciously roasted legumes.

Molecules called antibodies stick to the foreign food molecule leading to the release of a chemical called histamine.

Which makes you really itchy, or if the reaction is bad enough, it can cause anaphylaxis - where the entire body just goes haywire.

From dizziness to swelling to your ability to breathe.

So I started looking up like can you just develop an almond allergy or a tree nut allergy as an adult - you can and I said well what could cause it.

The only unusual thing was this almond milk, so I immediately made an appointment with an allergist.

We needed to determine if almonds had specifically caused this allergic reaction.

So honestly we did this food challenge and nothing happened.

Nothing happened so you're sitting there now and you still have no idea what triggered this, what it really was, or what you might meet again that could give you a problem.

And it could be nothing, it could be something else that I ate.

Emily had an allergic reaction to something.

In cases like these even doctors can be stumped.

In the meantime he told me when I left the office that day that I needed to operate as though I had a life-threatening tree nut allergy.

So he prescribed me epinephrine and I have an epinephrine injector that I have to carry with me everywhere.

I have to spend the next year carrying this around with me, and maybe have to use it on some mystery food that we don't know.

I keep coming back to one basic question, why would our bodies bother to have such extreme reactions?

Reactions that could kill us after a handful of trail mix, or a glass of milk.

The truth is we don't know why food allergies exist - there is a leading theory and I should stress this is just a theory, that allergies might exist thanks to parasites.

The part of our immune system that recognizes allergy causing food also reacts to certain wormy, buggy infections.

Humans are a lot cleaner than we used to be, back before hand sanitizer and indoor plumbing, and you know, science.

Today we don't have as many parasites entering our bodies, so maybe that bit of our immune system is just bored - so it's overreacting and attacking foreign-looking proteins in our food instead.

Our clean, sterile, no dirt eating lifestyles could be behind the rise in allergies of all kinds.

But that's just a theory, a parasite... wait that's not my catchphrase What am i doing?

Peanut allergies are the most common food allergy, affecting nearly 1 in 40 kids in the US.

In all, we know of at least 400 proteins for more than a hundred and seventy foods that cause allergic reactions with eight foods accounting for 90% of those.

Now a lot of people are allergic to shrimp and other shellfish, and a lot of those people are also allergic to little bugs called dust mites.

Now shrimp shellfish and dust mites are all invertebrates and all of them trigger allergies thanks to a protein called tropomyosin.

Well they share that protein and it's very different from anything our bodies make.

This is an example of cross reactivity, like if you're allergic to cashews you might also be allergic to pistachios or mangos since they're all in the same plant family.

I'm telling you evolution explains everything.

So how can you avoid food allergies for you or your kids?

Well, just a decade or two ago doctors recommended not giving young kids foods that commonly trigger allergies for at least the first few years of their life.

But that was actually the exact wrong advice.

Food allergy rates continued to rise, so doctors changed their recommendations.

Today's advice suggests parents should slowly introduce common allergic foods early, and in small amounts - and it seems like it's working.

Food allergy rates have stopped rising at least.

I mean we're parents now mm-hmm How does your having an allergy affect what you're introducing your chile - if it were up to me I probably would be incredibly more wimpy about it, but my wife my wife is introducing all these things.

She introduced all the all the nuts to her so far and she's not allergic.

So yeah, and I got nervous every time.

Which is fine.

If you already have a food allergy, unfortunately there's no cure.

We're developing treatments like getting the immune system accustomed to allergy causing foods in small doses, there's even a sticker that acts almost like a nicotine patch for peanut allergy.

But please remember always talk to a doctor before you attempt any treatment.

Sadly with food allergies there's still more questions than there are answers.

We know what's causing them, we know a little bit about how to prevent them, but we don't know why they exist or how to cure them.

It's really stressful to not know what caused it and to not have any reliable way of testing what caused it.

You take for granted when you don't have a food allergy - you can go wherever you want ready to eat anything and so you're automatically your world like shrinks quite a bit.

Every restaurant you go to, every lunch that you eat, if you didn't prepare it yourself I'm wondering like is this gonna have something in it that could kill me?

And am I allergic to almonds?

And if it's not almonds then what is it?

Are people taking me seriously.

That's a big concern that people who have food allergies.

But, it can be life-threatening.

Is it frustrating that people can't give you an answer about why this happened.

Yes, yes I would love a cure that would be great.

Do you've a cure are you gonna introduce?

A cure, well it's called exposure therapy.

But every scientific question that we know the answer to today was once a mystery just like this an answer barely out of reach, in the fog of not knowing yet.

Someday we'll figure it out.

Some nuts are just tougher to crack than others.

Stay curious.