
Dirt may explain why richest countries suffer diseases rarely seen anywhere else - cajuntrep
http://www.smithsonianmag.com/science-nature/The-Unintended-and-Deadly-Consequences-of-Living-in-the-Industrialized-World-199164051.html?c=y&page=1
======
pcl
I'm surprised that the article didn't touch on differences in childhood
mortality rates. The theory proposed has always made a lot of sense to me.
However, I would expect any reporting on the topic to consider the extent to
which the allergy-sufferers amongst us (such as myself) made it through
childhood because of better early childhood medical care, thus skewing the
later-in-life allergies and autoimmune disease stats downwards.

~~~
eric-hu
I wondered the same thing. As a follow-up to wazoox's comment, I looked into
the mortality rates of the areas for the studies.

I couldn't find the infant mortality rates of Petrozavodsk, so I went to
region (Republic of Karelia) instead:

Infant mortality rate of Karelia in 2000 [1]: 14.4 %

Of Finland: [2] 2.6 - 4.5 %

So at a 3-7x higher incident rate, infant mortality does seems like a
reasonable hypothesis. I wouldn't jump on the one-explanation-covers-it-all
stance though. Someone else in this thread mentioned Helmenthic therapy, using
parasites in a controlled manner to treat for allergies. If this treatment has
seen positive results, perhaps both your point and the proposed theory explain
the higher incidence of auto-immune diseases in first world countries.

[1]
[http://www.arcticstat.org/TableViewer.aspx?S=2&ID=12668](http://www.arcticstat.org/TableViewer.aspx?S=2&ID=12668)
[2]
[http://www.arcticstat.org/TableViewer.aspx?S=2&ID=12348](http://www.arcticstat.org/TableViewer.aspx?S=2&ID=12348)

~~~
pcl
Great links, thanks!

Agreed that both probably have an impact. I imagine that there's some sort of
scientific method out there to tease out the impacts of the two factors,
probably via an aggregation of a number of such studies.

------
kens
The NYTimes had a similar article a month ago describing the exact same
Russian and Finnish populations and suggesting lack of microbes might be
related to celiac disease:

[http://www.nytimes.com/2013/02/24/opinion/sunday/what-
really...](http://www.nytimes.com/2013/02/24/opinion/sunday/what-really-
causes-celiac-disease.html)

I'm pretty sure there was a HN discussion on this, but I can't find it.

Edit: in reply to another comment, the article claims that the two populations
are culturally, linguistically and genetically related, so genetics don't
explain the differences.

------
smegel
Is this really news or even a new idea? The idea that being exposed to "dirt"
or plentiful foreign germs/organisms can build the immune system is one I have
been aware of for as long as I can remember. Maybe it just hasn't been
"proved" yet.

~~~
adhd
To my understanding, the way this idea is being applied in research is new.
There is a difference between the presence of germs 'boosting' the immune
system and a lack of germs causing the immune system to target -- and severely
damage -- the entirely wrong enemy, as in the case of an autoimmune disorder.

------
tokenadult
The article reports an interesting observation: "Still, the 500-mile boundary
between Finland and this Russian republic marks one of the steepest standard-
of-living gradients in the world: Finns are seven times richer than their
neighbors across the border. 'The difference is even greater than between
Mexico and the U.S.,' Knip tells me."

Then the article gets into the main point: "Soon, studies from around the
world showed similarly surprising results. But it was germ-laden dirt that
seemed to matter, not air pollution. The children of full-time farmers in
rural Switzerland and Bavaria, for example, had far fewer allergies than their
non-farming peers. And a study following more than 1,000 babies in Arizona
showed that, unless parents also had asthma, living in houses with dogs
reduced the chances of wheezing and allergies later in life. Researchers
proposed that the more microbial agents that children are exposed to early in
life, the less likely they are to develop allergies and autoimmune diseases
later on. Studies also showed that baby mice kept in sterile environments were
more likely to face autoimmune disease, seeming to back what came to be called
the 'hygiene hypothesis.'"

I'm still puzzling how hygiene (in this sense) can be measured accurately over
the course of a lifetime, as my mother is a farmer's daughter who grew up in
the Great Plains during the Dust Bowl era, and thus was probably exposed to
plenty of allergens, but she has long struggled with hay fever and other
allergy symptoms. My wife grew up in even poorer circumstances early in the
development of a developing country, and spent a few years of her childhood
literally living on a dirt floor. But she has allergies now too. I wonder how
well exposure to dirt or to germs can really be quantified at the individual
level for reliable treatment/control studies of this issue, rather than this
kind of cross-sectional population comparison. For example, do I really, as a
parent, have any clear idea whether my children get more exposure to dirt or
less exposure to dirt than the typical American child who is allowed to play
outdoors and build sand castles and mud dams? I have no idea, and I'm not sure
anyone has an idea.

See "Warning Signs in Experimental Design and Interpretation"

<http://norvig.com/experiment-design.html>

by Peter Norvig, LISP hacker and director of research at Google, and "Worms,
Germs, and Dirt: What Can They Teach Us About Allergies and Autoimmune
Diseases?"

[http://www.sciencebasedmedicine.org/index.php/worms-germs-
an...](http://www.sciencebasedmedicine.org/index.php/worms-germs-and-dirt-
what-can-they-teach-us-about-allergies-and-autoimmune-diseases/)

by Harriet Hall, M.D. for more information about what we will need to find out
to be sure how much this interesting hypothesis has to do with our commonplace
diseases.

As the article also points out, "These findings don’t mean that people should
eschew basic hygiene. Its benefits are clear: In the past 60 years or so, our
overall life expectancy has continued to rise. The trick for scientists is to
determine exactly which early life exposures to germs might matter and
identify the biology behind their potentially protective effect."

And because I've seen recent threads here on Hacker News that include comments
underestimating just how much longevity and general health have improved in
the developed world, I'll share some links on those issues, some of which I
learned about from other Hacker News participants and others of which I
learned about from a demography of aging researcher. Girls born since 2000 in
the developed world are more likely than not to reach the age of 100, with
boys likely to enjoy lifespans almost as long. The article "The Biodemography
of Human Ageing" by James Vaupel,

[http://www.demographic-
challenge.com/files/downloads/2eb51e2...](http://www.demographic-
challenge.com/files/downloads/2eb51e2860ef54d218ce5ce19abe6a59/dc_biodemography_of_human_ageing_nature_2010_vaupel.pdf)

originally published in the journal Nature in 2010, is a good current
reference on the subject. Vaupel is one of the leading scholars on the
demography of aging and how to adjust for time trends in life expectancy. His
striking finding is "Humans are living longer than ever before. In fact,
newborn children in high-income countries can expect to live to more than 100
years. Starting in the mid-1800s, human longevity has increased dramatically
and life expectancy is increasing by an average of six hours a day."

[http://www.prb.org/Journalists/Webcasts/2010/humanlongevity....](http://www.prb.org/Journalists/Webcasts/2010/humanlongevity.aspx)

A comparison of period life expectancy tables and cohort life expectancy
tables for men and women in Britain

[http://www.ons.gov.uk/ons/rel/lifetables/period-and-
cohort-l...](http://www.ons.gov.uk/ons/rel/lifetables/period-and-cohort-life-
expectancy-tables/2010-based/p-and-c-le.html)

helps make the picture more clear. ("Period life expectancy" is what is
usually reported for a whole country. But cohort life expectancy provides a
better estimate of future lifespans of young people today,

[http://www.time.com/time/specials/packages/article/0,28804,1...](http://www.time.com/time/specials/packages/article/0,28804,1963392_1963367,00.html)

and is still steadily on the rise around the world.) Life expectancy at age
40, at age 60, and at even higher ages is still rising throughout the
developed countries of the world.

[http://www.scientificamerican.com/article.cfm?id=longevity-w...](http://www.scientificamerican.com/article.cfm?id=longevity-
why-we-die-global-life-expectancy)

~~~
lawtguy
I find the "Old Friends" hypothesis a good answer for why hygiene causes
allergies: <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1774411/>

The basic idea is that the human immune system has co-evolved with a number of
immune suppressing parasites. Hygiene has greatly reduced the number of these
parasites we're exposed to and without them the human immune system is too
reactive. That extra reactivity results in our immune system attacking
proteins that are harmless, like pollen or peanuts.

So hygiene is definitely extending human lifespans by preventing us from
getting deadly bacterial and viral diseases. But it may indirectly be causing
auto-immune diseases. The good news is it's not all that hard to introduce
safe parasites back into our bodies:
<http://en.wikipedia.org/wiki/Helminthic_therapy>

~~~
cajuntrep
Cool link on the Helminthic therapy! I've never heard of it before.

~~~
CasimirCelerity
It's a pretty cool idea. Although it's a tad simplistic way to consider the
immune system, our bodies mount two types of responses: Th1 and Th2. Th1
favors our immune cells directly killing our own cells and baddies. Th2 favors
our immune cells producing lots of antibodies which then tag baddies for
destruction.

In Crohn's disease, our bodies, for whatever reason, seem to be skewed towards
producing a really unnecessary Th1 response in the gut which causes our bodies
to self-destruct the GI tract. By giving hookworms to a patient, the hope is
that the needed worm-killing Th2 response (worms are too big for really an
effective Th1 response and need to be coated in antibodies and essentially
repeatedly nuked with cytotoxic chemicals) will shift the balance in the
patient's gut from Th1 towards Th2, thus eliminating their Crohn's
manifestations and symptoms. Really cool idea.

------
aneth4
After living in China for 4 years, my allergies are gone, and while I got sick
here a lot then, I have not had a serious cold in 6 years.

The allergy experience mimics many other people who spent time in Asia. The no
colds - I think it's related, but most people do still get sick. I used to get
terrible colds every few months my entire life. I can now scuba dive because
my ears aren't constantly damaged by frequent sickness and fluids.

My theory has always been that allergies are a symptom of an under-utilized
and under-exercised immune system. Our bodies are designed to be under
constant attack. Much like the US is unable to resist invading countries when
the world is at peace, our immune system can't stand a sterile body with no
foes.

------
webwielder
That's why I ride the MUNI each and every day.

~~~
hexagonc
Fun anecdote: There was a worse than usual flu season here in Boston and since
a lot of other people in the office were getting sick, I was wondering if I
should get the flu vaccine. Being lazy, I didn't bother with the vaccine, yet
I have never once gotten the flu, despite taking a crowded bus and subway to
work every day. Furthermore, I don't recall the subway or buses ever being
filled with lots of sick people. I suspect most of the sick people in the
office drove to work.

------
swah
Here in Brazil, elderly people say that kids should receive a healthy dose of
"Vitamin S" (S referring to 'sujeira' - dirt in portuguese)

------
papaver
its always amusing to read articles from respected sources about beliefs one
has held for a long time. it feels mostly obvious to me that underexposure to
germs can lead to more problems than fix. i guess a lot of my beliefs could
come from visiting india and less developed countries.

its quite scary how many daily/regular routines come from people with ulterior
motives. reminds me of the diamond article recent published by pricenomics.
most people are ok with conforming to the norm without question.

anti-bacterial soap? really? im pretty sure all bacteria is not bad, and some
actually quite helpful. regular shampoo? makeup constantly blocking the pours,
not allowing the skin on the face to breath? deodorant?? i wonder how the
toilet paper companies convinced the entire western culture that washing their
bum with their hands was disgusting. isn't it more disgusting to have a bum
thats not washed?? ah the magic of the marketing department.

~~~
pault
The thing I most regularly miss about living in Asia is the bum gun. Wiping
with paper is so gross.

<http://www.memock.com/2011/11/15/the-bum-gun/>

------
jasonkester
I'm going to filter this through my skewed outlook on the world and conclude
that it's another datapoint in support of travelling the world as much as
possible.

We uprooted our 10 month old son last winter and set up shop in a little
fishing village in Nicaragua for a few months. He spent his time eating the
local dirt while we surfed. And now we have conclusive proof that this was the
Best Thing We Could Have Possibly Done for him.

Glad to hear I'm such a great parent.

This article also rings true for me from a personal perspective. I spend a lot
of time in the developing world, and make a point of brushing my teeth in the
local tap water and eating those poisonous lettuce leaves and local cheese
that the Lonely Planet warns you so strongly against. I find that over the
years I've gradually stopped getting sick at all while on the road.

I think there's something to be said for training your immune system.

~~~
ndonnellan
"And now we have conclusive proof". Confirmation bias? Did you read the same
article I did?

>> Scientists believe dirt __could explain __why some of the wealthiest
countries suffer from afflictions rarely seen in less-developed nations

The plural of anecdote is not data. Even on HN.

~~~
jasonkester
More conclusive proof that tone doesn't come across well in writing. Re-read
that comment and try to imagine the silly grin on the face of the author as he
states things that are clearly not true even to the most biased observer as
though they were fact, sure in the knowledge that he doesn't need to qualify
that it's meant to be humorous, as that is clearly implied.

~~~
ndonnellan
Apologies. I get frustrated with irony of personal stories usually following
an article which is discussing the scientific method. I rarely respond;
probably should keep it that way. xP

------
andrewl
There is research suggesting that exposure to bacteria ( _Mycobacterium
vaccae_ in this case) can help cure depression. I first read about it in this
article from _The Economist_ :

<http://www.economist.com/node/8956457>

------
contingencies
It seems like without waiting for the results of this study there's a more
simple solution - to protect your children from _rich man's disease_ (of all
kinds), travel with them to developing countries and live there for reasonable
periods of time alongside the locals, how they live ("When in Rome"). Not only
will they be more worldly, gain linguistic prowess and be better adjusted to
foreign cultures in general, but they are likely to receive immune system
benefits.

<http://en.wikipedia.org/wiki/Rich_Man%27s_Disease#Cause>

------
refurb
There is a company that is putting the hygiene hypotheses to the test.
Coronado Bioscience is trying to treat Crohn's disease with pig whipworm eggs.
The worms can't live in a human host, but they do develop into full worms and
thus trigger the body's immune system.

The initial phase 1 studies were quite remarkable, but I'm keeping an eye out
for the phase 2 studies which should provide more robust data.

[http://biotechtranslated.com/2011/07/30/the-hygiene-
hypothes...](http://biotechtranslated.com/2011/07/30/the-hygiene-hypothesis-
goes-on-trial/)

------
kmook
I recently read a book about this very concept, the author went over hundreds
of studies like the one you just read and has some interesting conclusions, in
the book titled "An Epidemic of Absence"

------
malandrew
I don't know about allergies, but I was under the impression that improving
hygiene standards was directly related to the polio epidemic of 1916 [0]. I
was surprised that it and maternal antibodies were not mentioned once in the
linked article.

[0] <http://www.virologyj.com/content/pdf/1743-422X-4-70.pdf>

------
giardini
And the "dirt vaccine" seems to boost/correct the immune system of both pigs
and men:

<http://www.guardian.co.uk/uk/1999/sep/18/5>

and

[http://www.thepigsite.com/swinenews/7892/dirt-vaccine-
resear...](http://www.thepigsite.com/swinenews/7892/dirt-vaccine-research)

------
rikacomet
This reminds me of my general curiosity about, how our muscles develop in
regards to workout during early childhood, and during our adulthood. Its a
vague feeling, but I want to share it, if it helps.

------
Zimahl
I can buy trying to figure out allergies, but Type I diabetes? It's clearly
hereditary, rarely showing up without some family link. Finland may have a
high rate due to a lack of ethnic diversity.

~~~
knightni
Hereditary, but not in a strong sense - to quote the american diabetes
association:

> In general, if you are a man with type 1 diabetes, the odds of your child
> getting diabetes are 1 in 17. If you are a woman with type 1 diabetes and
> your child was born before you were 25, your child's risk is 1 in 25; if
> your child was born after you turned 25, your child's risk is 1 in 100.

Even if both partners are diabetic, the risk is only 1 in 10 to 1 in 4. This
strongly implies that what is heritable is the vulnerability to getting
diabetes, rather than getting diabetes itself. There is, presumably, some
trigger that also needs to occur.

------
soperj
This is probably just a nitpick but it annoys me when they say minus 40
degrees Fahrenheit, since it doesn't matter.

~~~
eurleif
The fact that -40 C = -40 F is a random bit of trivia that not everyone can be
expected to know. If it just said -40 degrees, it would be confusing to anyone
who wasn't aware.

------
creed0r
From the article: “It was so unexpected,”...

George Carlin on germs:
[http://www.youtube.com/watch?feature=player_detailpage&v...](http://www.youtube.com/watch?feature=player_detailpage&v=X29lF43mUlo#t=29s)

Was it? Really?

------
eof
I always just assumed it was because rich countries are full of lazy-fat-
fucks.

~~~
josephagoss
Interesting generalization, I am from a very rich country (Australia) and
everyone I know is extremely hard working.(myself and my colleges are however,
not rich in our land)

Everyone is living life well, studying hard or working. I am unfamiliar with
any "lazy-fat-fucks" in my neck of the woods yet I should be seeing them
everywhere due to your over the top criteria. (Being in a rich country)

~~~
Volpe
Caveat: Working Hard in Australia - might be considered "Lazy and fat" in
another country.

40 hour work weeks is hardly "Working extremely hard"

~~~
josephagoss
Most of the older people I know that are "working hard" are running
businesses, no 40 hour weeks there. Also Me and my friends are not wealthy but
we work and study constantly. Also lots in my family work in the mines which
are long 12 hours days many in a row (my Dad has it easier, only 10 days in a
row of 12 hour days). I know very few people working 40 hour weeks.

