
Can the Bacteria in Your Gut Explain Your Mood? - kareemm
http://www.nytimes.com/2015/06/28/magazine/can-the-bacteria-in-your-gut-explain-your-mood.html
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shabble
Another thing I've been pondering occasionally is what this and other
discoveries might mean if cryonic neuropreservation (head/brain only) storage
& reversal is ever practical, or if full head transplants become a viable
surgery.

Just how much of actual _personness_ is stored in places other than just the
brain? Surely the hormonal (endocrine?) systems of the body, as well as things
like the microbiome are going to play important roles, although I have no clue
if they're _necessary_.

~~~
mjklin
In _Principles of Psychology_ , William James speculated that any kind of non-
corporeal afterlife would necessarily be non-emotional, since our emotions are
felt in our bodies rather than our brains.

~~~
uberlux
If we ever managed to emulate our consciousness on other hardware, wouldn't we
be also able to emulate bodily sensations and emotions?

~~~
shabble
As an ignorant layperson, I kind of assume we could. A virtual machine
_thinks_ it has a network card and a hard disk and whatever, but it's just
being given what it expects to see.

The problem I was imagining is that right now we're not recording that data in
the way that we're, e.g. scanning the brain's neuron connections. So even if
we could rebuild/emulated Frozen Jim's Brain, there may be permanent loss of
essential information that was distributed around his lymph system or
population of gut bacteria such that 'the same person' cannot be
reconstructed.

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chippy
This reminds me of the cases where a course of antibiotics for something
unrelated cured chronic back pain.

[http://www.naturalnews.com/040354_chronic_back_pain_antibiot...](http://www.naturalnews.com/040354_chronic_back_pain_antibiotics_spinal_injury.html)

It also reminds me of Russian "phages" bacterial concoctions as cures for
certain illnesses.
[https://en.wikipedia.org/wiki/Phage_therapy](https://en.wikipedia.org/wiki/Phage_therapy)

~~~
CuriouslyC
I think this is one of the mechanisms behind detoxifying fasts. Severe caloric
restriction for an extended period (I'm guessing at least 3 days) results in
major changes in your gut flora, some of which may persist upon resumption of
a normal diet.

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atmosx
The problem with this emerging theory about bacteria in the Gut modulating
mood, obesity, etc. is very hard to be proved in an _absolute_ way. The number
of bacteria's in the gut is extremely high. I think we need much more research
on the topic to be absolutely sure we know what we're talking about.

There is a growing awareness about probiotics, but most of the studies I read
are not convincing enough, as of today.

~~~
DanBC
It's tricky for mood because you use self-reported descriptions of mood.

But for obesity it's not that hard.

Here's one for anorexia and bulemia.
[http://www.nature.com/tp/journal/v4/n10/full/tp201498a.html](http://www.nature.com/tp/journal/v4/n10/full/tp201498a.html)

(my description might be wrong) They start with a prediction; they modify mice
and show that prediction is true; they then find human samples (staff and
patients at an inpatient ED unit) and they find the staff don't have the
particular gut flora while patients do. It's going to be really hard to get
ethical approval to give the gut flora to healthy people - to give those
people anorexia, so there is a missing step.

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msbroadf
I had my entire large intestine removed over several operations, and i felt no
difference in my mood

~~~
jliptzin
Wow, usually the first step is to prescribe antidepressants

~~~
msbroadf
No, it was removed for ulcerative colitis. If gut bacteria affected mood I
would have noticed now I have a lot less but there wasn't any change.

~~~
Fomite
The usual issue is not the overall _amount_ of gut bacteria, but the
composition. While bowel surgery _can_ disrupt the composition of your gut
flora, it need not have to, and if there was no major accompanying lifestyle
changes, it's possible it eventually returned to equilibrium.

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cpncrunch
It's a little concerning that Mazmanian believes that diet can help autism,
when all the placebo-controlled trials show that none of the weird and wacky
diets actually work.

~~~
randomname2
While not conclusive, there is actually some evidence a ketogenic diet may
help.

~~~
cpncrunch
As far as I can tell it was uncontrolled, which doesn't really tell us
anything (as there will be a large placebo effect).

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blfr
If this effect was large, wouldn't we have spotted it by now?

Doctors prescribe antibiotics for nearly anything nowadays. Along the
antibiotic, you will get some sort of probiotic (selected strains of
bacteria), not to mention all the yogurt and similar products we're eating.
Millions of people around the world do it every year. At least some will
correctly follow instructions, finish the round of antibiotic, and take the
supplement for a while longer.

Essentially, we blast and replace bacteria in our guts all the time in a
massive natural experiment. Yet I haven't seen any life-changing results.

~~~
vanderZwan
> Yet I haven't seen any life-changing results.

Not trying to be a smartass, but "not seeing something" is not really a
convincing argument if you have never looked for it before. Especially here,
given that there is no obvious feedback loop to give us hints at the relation
between the gut flora and our mood. (are you aware of changes in your
digestive chemistry and gut flora? How would you connect that to emotional
changes then?)

But as for evidence: there was that one time during a double blind research
trial of a certain experimental probiotic treatment of cancer where the
researchers could tell who was in the control group and who wasn't, because
the people who got the probiotic treatment were much happier (I saw this
mentioned in a New Scientist article on gut bacteria from around 2011 - can't
get to it now because it's behind a paywall).

Also, the article specifically addresses this:

> ‘‘Dr. Lyte,’’ he later asked at a question-and-answer session, ‘‘if what
> you’re saying is right, then why is it when we give antibiotics to patients
> to kill bacteria, they are not running around crazy on the wards?’’

~~~
blfr
It's presented as a dismissive question with no answer. But with the number
and amount of antibiotics prescribed, wouldn't you expect a lot of curious,
seemingly miraculous changes by accident?

You know when you take antibiotics. You have a clear time frame, and the event
is unusual enough that it should stand out.

~~~
vanderZwan
Except that for a cause-effect relationship, you need a kind of "all else
being equal" scenario. But since we take antibiotics when we are ill, we
already are in an unusual state of the body. So any mood swings, if noticed at
all, are just as likely (and given that we tend look among the familiar things
first, I'd say _more_ likely) to be attributed to things like poor sleep or
other side-effects of whatever disease caused you to take antibiotics.

~~~
blfr
There should be a lasting effect when you replace your gut bacteria, not just
some mood swings.

~~~
Retra
Says who? You could easily imagine your body to acclimatize to new bacteria.

~~~
blfr
Says the theory that gut bacteria explains mood, the title of the OP.

~~~
Retra
"Mood" is not a lasting effect.

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cpncrunch
I'm curious why these articles are posted so often on HN. Do a lot of people
here have mood disorders? If so, would it not be better to look at the more
obvious causes -- lifestyle and stress -- rather than trying to pin the blame
on some outside entity?

There really isn't much if any evidence supporting this hypothesis at the
moment, and even if there is an effect it appears to be relatively minor.

~~~
Fomite
As someone mentioned, there's a lot of bio/pharma/med people who read HN,
myself included.

Also, if this _is_ true, you're getting closer to being able to 'hack' your
own microbiome. Microbiota transplantation as a wetware patch is a pretty cool
concept.

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feefie
Giulia Enders was recently interviewed on TVO (public television channel in
Ontario) that you might enjoy: [http://tvo.org/video/213722/giulia-enders-gut-
reaction](http://tvo.org/video/213722/giulia-enders-gut-reaction)

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shabble
_Vitals_ by Greg Bear is an interesting (fictional) take on this premise, in
which modified bacteria can be be weaponised to influence people's behaviour.

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chopman
I remember an old saying about drinking the water from boiled potato to
improve mood.

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phil_s_stein
No it cannot[1].

[1] See Betteridge's Law.

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dschiptsov
There is a simpler question - could one tell anxiety from hunger? (I can't) or
the feeling of being hungry "reuses anxiety" in context?

This explains why stressed people are overeating - they misinterpret their
anxiety as feeling hungry and develop a habit of "eating it over".

Bacteria stuff is just BS.

~~~
rpedela
"Bacteria stuff is just BS."

Why? References?

"There is a simpler question - could one tell anxiety from hunger? (I can't)
or the feeling of being hungry "reuses anxiety" in context? This explains why
stressed people are overeating - they misinterpret their anxiety as feeling
hungry and develop a habit of "eating it over".

Actually it doesn't. Why are they feeling anxious? How do they misinterpret
anxiety for the feeling of hunger? Why is the feeling of anxiety and hunger
the same (as you assert, I strongly disagree). It is not even close to as
simple as you suggest. Maybe bacteria has a role and maybe not. What is known
is that the microbiome does have a larger role to play then we currently
understand/realize. To what extent and exactly how is still an open question.

~~~
dschiptsov
Because which set of bacteria one has in ones gut depends of location, season,
humidity, air quality, traditional foods, _water sources_ , other bacteria an
another hundred factors.

Anxiety disorders are human universal.

