
Why do we have allergies? - Hooke
http://mosaicscience.com/story/why-do-we-have-allergies
======
pdabbadabba
> Suddenly the misery of allergies took on a new look. Allergies weren’t the
> body going haywire; they were the body’s strategy for getting rid of the
> allergens.

Well of course. I'm just a layman when it comes to allergies, but I thought it
was well understood that allergies were the body's inflammatory reaction to an
allergen, i.e., an attempt to eliminate (or otherwise neutralize) the
allergen. The problem is that, according to the conventional wisdom, the
body's reaction to allergen is _mistaken_. Presumably the body is attempting
to target and eliminate something that is actually harmful, but it winds up
responding to something harmless, or by triggering a response so severe that
it does more harm than good. That's, broadly speaking, the difference between
an allergen and a pathogen/poison. A poison/pathogen will actually harm you if
it is not eliminated. An allergen will not (or, at least, not in proportion to
the severity of the reaction. But I don't see why the observation above has
anything to say about the real question, which is why does the body sometimes
mistakes one for the other, and freaks out in the presence of harmless
substances?

~~~
chaosfactor
I have theorized that allergies, such as cat allergies, may, in some cases, be
your body's way of warning you that there are Big Cats in the vicinity and you
should GTFO.

~~~
saraid216
Loudly sneezing, blurring your vision, and ruining your sense of smell are
really not conducive to surviving an encounter with a big cat.

I mean, you might piss it off if you sneeze on it, I guess. Yay?

~~~
jccooper
It's an environmental allergy, not an emergency one. If you notice you feel
like crap in a certain place (because cats like to lurk there), and
subsequently avoid it, that's a win.

Not that I necessarily believe that's a good explanation for allergies, but
it's plausible enough to think about.

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littletimmy
I spent my early childhood in a third world country, and I never heard of
anybody having an allergy. It was one of the surprising things I learned about
when I moved to the first world.

~~~
diaz
In my case it seems I only got what seems to be allergies when I moved to the
city some 5 years ago. In my rural area I don't remember ever sneeazing so
much as if I was gonna die.

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DickingAround
The structure of this article makes it difficult to read. It's a news article
written as a story; endless lead-up and back story where there should have
been thesis and defense of that thesis. Or at least summary and then summary
with more detail and then full details.

~~~
floatrock
Billy was just a regular ol' schmuck in Anytown, USA who wouldn't read
anything technical unless there was a human element in the story that he could
relate to.

Not sure if there's a name for that literary mechanism, but pretty much every
NYT article and every other TED talk starts out with that kind of human
element. A thesis and a technical defense of the thesis is what journal
submissions do... other mediums find their engagement through the human
struggle (eg the immigrant who escaped the crumbling soviet university system
and became the nobel-slighted yale academic with a promising rogue theory).

------
bad_user
> _“You’re sneezing to protect yourself. The fact that you don’t like the
> sneezing, that’s tough luck,” he said, with a slight shrug. “Evolution
> doesn’t care how you feel.”_

Well, as somebody that has allergic asthma, I've had episodes so severe that I
thought I was going to die and I ended up in ER about 3 times. Then due to a 1
year treatment with Symbicort, my asthma is now in control and I haven't had
episodes or felt the need for treatment in years. However asthma can always
come back and it is something you leave with.

Allergic asthma is also correlated with heart problems, like for example I
suffer from supraventricular tachycardia from time to time and treatment for
one has a negative impact on the other - broncho-dilators or corticosteroids
are known to produce tachycardia episodes as side-effects.

Therefore I have a hard time not thinking about my asthma as being a disease
and the only reason I can have a normal life right now is due to modern
medication that wasn't available 15 years ago.

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bjourne
Is the cleanliness theory completely discounted now? It's not mentioned in the
article. The idea is that there are so few pathogens in the environment during
childhood so the immune system can't tune itself. So then it reacts out of
proportion to some trigger substances which then form the basis of the
allergy.

~~~
piptastic
This study supports what you are mentioning:
[http://www.health.harvard.edu/blog/children-eat-peanuts-
earl...](http://www.health.harvard.edu/blog/children-eat-peanuts-early-age-
may-prevent-peanut-allergies-201502237751)

However, I'm not sure it would be called a cleanliness theory..

~~~
rsync
It's called the hygiene hypothesis:

[http://en.wikipedia.org/wiki/Hygiene_hypothesis](http://en.wikipedia.org/wiki/Hygiene_hypothesis)

~~~
piptastic
Seems like a misnomer then, eating allergies wouldn't be considered hygiene
related, would they?

Even pollen isn't really hygiene related.

------
_Adam
Interesting, and it makes sense. To summarize:

1964 theory: Allergies are caused by a misfiring reaction to generally
harmless compounds that have a similar structure to proteins presented by
parasitic worms.

Medzhitov's theory: Allergies are caused by the body mounting an intense
immune response to compounds that are actually harmful and need to be
eliminated.

..or so the article says. I don't know how true that is.

What I find much more probable is that the answer is somewhere in between.
It's ridiculous to suggest that ALL allergens must look like worm proteins to
the body. Why just worms? Why have such a specific restriction?

However, I also don't agree entirely with Medzhitov. In order for his theory
(as presented in the article) to be correct, he has to prove that every single
allergen is actually harmful. How does this explain food allergies? Why do
peanuts harm one person but not another? It's possible, but it's a big task to
prove.

So while I don't agree entirely with him, I think his theory is very close. I
believe it more probable that some allergens are actually harmful, but that
there are also harmless ones that are interpreted as harmful by the body and
thus elicit an allergic response.

The biggest question to answer is why different people have different
reactions to allergens. We're all exposed to pollen, after all. But.. what if
there's an (unknown) compound that looks like pollen to the body, but is
actually harmful? It would rightfully train the immune system to react to a
specific molecular signature to eliminate the threat, but simultaneously train
it to wrongfully respond to a harmless element.

No idea! I look forward to seeing the outcome of his research.

~~~
julie1
Oh! rediscovering basic science: allergies are violent reactions to toxins!

My physic teachers used to say science is not about why but about how.

Why is religion, how is science.

------
zerocrates
So, is there a compound in say, peanuts, that "rips apart cells"? I can see
the logic as applied to bee venom (though bee stings might in themselves be
enough of an incentive to leave the area) but not so much the many other
seemingly harmless allergens.

~~~
crimsonalucard
I think the article is implying that heightened defenses equals heightened
false positives. Peanuts would be a false positive to something else that is
actually harmful.

So if you have an allergy to peanuts it means your body is primed to defend
against something in which peanuts are only a side effect. The author implies
that if you have allergies, you have better defenses against other things.

------
rottyguy
What I always puzzled over was the following: if our main goal in life is, in
fact, to survive/live (and insure the existence of our species through
procreation), why would our body, in the case of an allergenic reaction, mount
a defense mechanism that could kill us? If your body swelled up to the extent
of restricting your ability to breath, why wouldn't your body recognize this
as a threat to your existence and counteract the measure? Even if your system
made a mistake reacting to the allergen, wouldn't the act of killing itself
(your body) trigger another prioritized reaction to take measures to save
itself?

~~~
JoshTriplett
Why would the body include congenital defects of any kind? Bugs and
duplication errors that didn't produce useful results. One mutation or genetic
development might lead your body to be predisposed to overreact to otherwise
harmless allergens; a similar mutation might ramp up your immune system so
that you're less vulnerable to fatal diseases.

Don't anthropomorphize evolution; it has no intent, and does not actively
"select" beneficial traits. Over time, whatever traits happened to propagate
will propagate. Some of those will be beneficial; others just didn't happen to
kill people.

Notice that there's no widespread anaphylactic-level allergy to, for instance,
water, or some standard component of atmosphere. But an allergy to peanuts
does not systematically kill everyone who has it before they can reproduce.

~~~
rottyguy
I'm not referring to evolution or defects here unless you're implying that it
is a defect that our body would willingly choke itself to death in reaction to
an allergen (I agree that it's probably a defect that we react to the allergen
in the first place)

~~~
kolinko
Exactly that. Your body has a defect that causes it to choke itself to death
in certain circumstances.

And thanks to the evolution, if not for science, the defect might be
eliminated in a few generations. Or not - perhaps this is an optimal variant
of immune the immune system. That is - 90% of organisms will have an excellent
immunity, but it will go haywire in 10% of cases, whereas an alternative would
be a system with 99% organisms having just an average immune system, but 1%
being haywired.

Finally, evolution has no "target" or "goal" really. Some features will be
broken, and some will be useless. Some may serve a purpose that's beyond our
understanding or extremely complex.

------
stepmr
Allergies are awful. Throughout my twenties I "suffered" what I thought was
chronic fatigue syndrome, only to discover later this year it was actually
just an Allium allergy (Onions, Garlic etc). I'd estimate that this was at
least a 50% drop in my overall productivity during what could have been some
of my most productive years. If anyone is suffering from allergies I highly
suggest experimenting with your diet.

~~~
kolinko
How did you find out that you had this allergy? Do the standard tests pick it
out?

~~~
stepmr
The standard tests didn't get it. I actually discovered it when I just totally
gave up (at this point I'd been to doctor for numerous blood tests -
especially for mono). I cook a lot, and have always eaten fairly well. I just
got tired of it... so I ate a lot of terrible food for a month, mostly fried,
and I felt awesome. Then i started to get fat. So, i started cooking again.
The first meal was beef stew. I ate it, then felt terrible. So I eliminated
everything in it, and reintroduced them one-by-one to my diet. The onions were
obvious, garlic less so.

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eric_h
> The fact that you don’t like the sneezing, that’s tough luck

I had a teacher in high school who would call out any student who suppressed a
sneeze. He used to say "It's one of the best natural highs you can get! Don't
fight it, just cover your mouth!"

I tend to agree, but they do get annoying when they are incessant.

------
Practicality
For some reason, reading all this makes me feel like I am having an allergic
reaction. I wonder if there are some psychosomatic triggers as well. Not
saying it's all that, or anything, but worrying about it seems to make it
worse.

------
bane
Allergies are really weird things. They run from the mild, like a slight itch
some people get when they eat peaches, to deadly.

I have a neighbor who's daughter is basically deadly allergic to just about
everything anybody would consider normal. It's so bad that they struggle
combining foods she can eat to get her complete nutrition...it's so bad that
she's gone to the hospital with respiratory issues from accidentally coming in
contact with somebody who had come in contact with one of her allergy
triggers...

Her mother fought (and lost) a campaign to keep eggs out of school meals
because they're one of the guaranteed-to-kill-her-daughter triggers. I had no
idea how many foods have egg in them, but it appears to be just about all of
them.

So you sit down and think about this, there is no way evolution could have
possibly produced a person who's immune response to fairly normal
environmental factors would be to send her into immediate shock, stop her
breathing and kill her...it's just not possible, unless she's a random
mutation, her entire genetic line would have been killed off the first time
they encountered a wild grass or tried to eat a wild egg or whatever of the
other couple dozen triggers she has. (I'm not ruling out that there may be
some genetic predisposition to a wildly out of control immune system). So my
conclusion is that it either has to be environmental (which genetics could
make her predisposed to some combination of genes and environment that's
gotten her here) or behavioral, the clean house theory (which I suppose also
ends up being environmental in a way).

I think it's also possible, knowing her mother, that once she found out she
was allergic to one thing, helicopter parenting stepped in and her exposure to
other normative immune triggers was stopped, perhaps making things worse.

This year her mother finally started taking her to some kind exposure therapy
where she's training her system to be able to handle eggs. Apparently so far
successfully. So my guess is that she probably just needed to grow up getting
dirty and eating all kinds of stuff to train her system.

Another story, my wife and I were out at he seashore some time ago for
vacation. Of course we ate a bunch of seafood there, something my wife grew up
with (growing up in South Korea) and I didn't (growing up a normal picky
American). One night, her eyes and mouth swelled up and we determined she must
have an allergy to something she ate (she has no other allergies we know of).
When we got back we took her to an allergy specialist and they did a whole
bunch of tests and she came back with some kind of alarmingly high measure in
some blood test. They told her to stop eating some class of foods and a bunch
of other stuff and to start carrying around an Epinephrine injector.

The thing is, _that was it_. They had no information at all for why she was
suddenly "deathly" allergic to food she'd literally been eating weekly for her
entire life (whatever the measure was in her blood, it was so high they sent
it off to another senior specialist for further comments since they had never
seen it that high in their office...an allergy specialist clinic).

They also had no information later on why, when she ate the same foods they
warned her against (she's stubborn) she had absolutely zero reaction and
continues to have no reaction to this day. The whole testing process looked
reasonably scientific, with the grid of pin pricks and before and after blood
draws and tables full of numbers from this or that blood factor. But in the
end it seemed like the specialists knew no more about the subject than either
of us, and we didn't know anything at all!

Very little has done more to shake my belief in modern medicine than the
series of interactions with her doctors.

~~~
onaclov2000
I am definately no expert, but reading abouy allergic load is fascinating. I
_think_ the general idea is you have a pitcher of allergies, when it gets full
you see a reaction. So while in many cases you may never see a response, with
enough allergies in play, you might have a more severe reaction to an item
than normal if you are overloaded, this doesnt only apply to food and or
pollens, but also potentially airborne chemicals (i mean we probably are
pumping a variety of new things in the atmosphere i would guess) i find
allergies and why we have them fascinating(i Am also allergic to tons of
stuff, but hardly notice a _reaction_ except to peanuts and other nuts. Out of
80 items i wasnt allergic to lobster, chicken,and bananas, random i know). I
also wonder if your allergic load is high, you might show a reaction for
something that you normally dont have a reaction to in a skin test... i would
love to experiment.... hahahaha

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MichaelCrawford
Why aren't the people who work in restaurants concerned about food allergies?
It's not so much that they could kill a diner as that they could get sued. :-/

"We'd both like the chef's choice please. But no tuna for her, she's allergic
to tuna."

"No substitutions!"

"But she's allergic to tuna!"

"NO SUBSTITUTIONS!"

"Tuna could kill her. Anaphilaptic shock would lead her trachea to swell shut
so she would suffocate."

"NO! SUBSTITUTIONS!"

"Ok look I'll just trade some of my sushi for her tuna."

My concern though was that her allergy might be so bad that just having a
little tuna juice on her plate, or for her other sushi to be cut on the same
chopping board or with the same knife as the sushi could kill her.

At least my father explained to me how to do a tracheotomy with a pocketknife
and a ball-point pen.

Much less than a single peanut can kill someone, yet I see peanuts served at
restaurants all the time.

~~~
eric_h
If you're allergic to tuna, you shouldn't eat at a sushi restaurant.

~~~
MichaelCrawford
That was the very first time in her entire life she had eaten sushi.

She was depending on me to ensure she wasn't killed by her supper.

