The surprisingly charming science of your gut | Giulia Enders
A few years ago,
I always had this thing happening to me,
especially at family gatherings
like teas with aunts and uncles
or something like this.
When people come up to you,
and they ask you,
“So, what are you doing?”
And I would have
this magical one-word reply,
which would make everybody happy:
I’m going to be a doctor.”
Very easy, that’s it,
everybody’s happy and pleased.
And it could be so easy,
but this effect really only lasts
for 30 seconds with me,
because that’s then the time
when one of them would ask,
“So, in what area of medicine?
What specialty do you want to go into?”
And then I would have to strip down
in all honesty and just say,
“OK, so I’m fascinated with the colon.
It all started with the anus,
and now it’s basically
the whole intestinal tract.”
And this would be the moment
when the enthusiasm trickled,
and it would maybe also get,
like, awkwardly silent in the room,
and I would think this was terribly sad,
because I do believe
our bowels are quite charming.
And while we’re in a time
where many people are thinking about
what new superfood smoothie to make
or if gluten is maybe bad for them,
actually, hardly anyone seems to care
about the organ where this happens,
the concrete anatomy
and the mechanisms behind it.
And sometimes it seems to me
like we’re all trying
to figure out this magic trick,
but nobody’s checking out the magician,
just because he has, like,
an embarrassing hairstyle or something.
there are reasons science
disliked the gut for a long time;
I have to say this.
So, it’s complex.
There’s a lot of surface area —
about 40 times the area of our skin.
Then, in such a tight pipe,
there are so many immune cells
that are being trained there.
We have 100 trillion bacteria
doing all sorts of things —
producing little molecules.
Then there’s about 20 different hormones,
so we are on a very different level
than our genitals, for example.
And the nervous system
of our gut is so complex
that when we cut out a piece,
it’s independent enough
that when we poke it,
it mumbles back at us, friendly.
But at least those reasons are also
the reasons why it’s so fascinating
It took me three steps to love the gut.
So today, I invite you to follow me
on those three steps.
The very first was just looking at it
and asking questions
like, “How does it work?”
and “Why does it have to look
so weird for that sometimes?”
And it actually wasn’t me asking
the first kind of these questions,
but my roommate.
After one heavy night of partying,
he came into our shared-room kitchen,
and he said, “Giulia, you study medicine.
How does pooping work?”
And I did study medicine
but I had no idea,
so I had to go up to my room
and look it up in different books.
And I found something interesting,
I thought, at that time.
So it turns out, we don’t only have
this outer sphincter,
we also have an inner sphincter muscle.
The outer sphincter we all know,
we can control it,
we know what’s going on there;
the inner one, we really don’t.
So what happens is,
when there are leftovers from digestion,
they’re being delivered
to the inner one first.
This inner one will open in a reflex
and let through a little bit for testing.
So, there are sensory cells
that will analyze what has been delivered:
Is it gaseous or is it solid?
And they will then send
this information up to our brain,
and this is the moment
when our brain knows,
“Oh, I have to go to the toilet.”
The brain will then do
what it’s designed to do
with its amazing consciousness.
It will mediate with our surroundings,
and it will say something like,
“So, I checked.
We are at this TEDx conference — “
Maybe, if you’re sitting on the sides,
and you know you can pull it off silently.
But solid —
Since our outer sphincter and the brain
is connected with nervous cells,
they coordinate, cooperate,
and they put it back in a waiting line —
for other times,
like, for example, when we’re at home
sitting on the couch,
we have nothing better to do,
we are free to go.
Us humans are actually one
of the very few animals that do this
in such an advanced and clean way.
To be honest, I had some newfound respect
for that nice, inner sphincter dude —
not connected to nerves
that care too much about
the outer world or the time —
just caring about me for once.
I thought that was nice.
And I used to not be a great fan
of public restrooms,
but now I can go anywhere,
because I consider it more
when that inner muscle puts a suggestion
on my daily agenda.
And also I learned
something else, which was:
looking closely at something
I might have shied away from —
maybe the weirdest part of myself —
left me feeling more fearless,
and also appreciating myself more.
And I think this happens a lot of times
when you look at the gut, actually.
Like those funny rumbling
noises that happen
when you’re in a group of friends
or at the office conference table,
going, like, “Merrr, merrr…”
This is not because we’re hungry.
This is because our small intestine
is actually a huge neat freak,
and it takes the time in between digestion
to clean everything up,
resulting in those eight meters
of gut — really, seven of them —
being very clean
and hardly smelling like anything.
It will, to achieve this,
create a strong muscular wave
that moves everything forward
that’s been leftover after digestion.
This can sometimes create a sound,
but doesn’t necessarily have to always.
So what we’re embarrassed of
is really a sign
of something keeping
our insides fine and tidy.
Or this weird, crooked shape
of our stomach —
a bit Quasimodo-ish.
This actually makes us be able
to put pressure on our belly
like when we’re laughing
and when we’re doing sports,
because the pressure will go up
and not so much sideways.
This also creates this air bubble
that’s usually always very visible
in X-rays, for example,
and can sometimes, with some people,
when it gets too big,
or even some sensations of pain.
But for most of the people,
is just results
that it’s far easier to burp
when you’re laying on your left side
instead of your right.
And soon I moved a bit further
and started to look at the whole picture
of our body and health.
This was actually after I had heard
that someone I knew a little bit
had killed himself.
It happened that I had been sitting
next to that person the day before,
and I smelled that he had very bad breath.
And when I learned
of the suicide the next day,
I thought: Could the gut have
something to do with it?
And I frantically started searching
if there were scientific papers
on the connection of gut and brain.
And to my surprise, I found many.
It turns out it’s maybe not as simple
as we sometimes think.
We tend to think our brain
makes these commands
and then sends them down
to the other organs,
and they all have to listen.
But really, it’s more that 10 percent
of the nerves that connect brain and gut
from the brain to the gut.
We know this, for example,
in stressful situations,
when there are transmitters from the brain
that are being sensed by our gut,
so the gut will try to lower all the work,
and not be working
and taking away blood and energy
to save energy for problem-solving.
This can go as far as nervous vomiting
or nervous diarrhea
to get rid of food that it then
doesn’t want to digest.
Maybe more interestingly,
90 percent of the nervous fibers
that connect gut and brain
from our gut to our brain.
And when you think about it a little bit,
it does make sense,
because our brain is very isolated.
It’s in this bony skull
surrounded by a thick skin,
and it needs information
to put together a feeling
of “How am I, as a whole body, doing?”
And the gut, actually, is possibly
the most important advisor for the brain
because it’s our largest sensory organ,
collecting information not only
on the quality of our nutrients,
but really also on how are so many
of our immune cells doing,
or things like the hormones
in our blood that it can sense.
And it can package this information,
and send it up to the brain.
It can, there, not reach areas
like visual cortex or word formations —
otherwise, when we digest,
we would see funny colors
or we would make funny noises — no.
But it can reach areas
for things like morality,
fear or emotional processing
or areas for self-awareness.
So it does make sense
that when our body and our brain
are putting together this feeling
of, “How am I, as a whole body, doing?”
that the gut has something
to contribute to this process.
And it also makes sense
that people who have conditions
like irritable bowel syndrome
or inflammatory bowel disease
have a higher risk of having
anxiety or depression.
I think this is good information to share,
because many people will think,
“I have this gut thing, and maybe
I also have this mental health thing.”
And maybe — because science is not
clear on that right now —
it’s really just that the brain
is feeling sympathy with their gut.
This has yet to grow in evidence
until it can come to practice.
But just knowing about
these kinds of research
that’s out there at the moment
helps me in my daily life.
And it makes me think
differently of my moods
and not externalize so much all the time.
I feel oftentimes during the day
we are a brain and a screen,
and we will tend to look
for answers right there
and maybe the work is stupid
or our neighbor —
but really, moods can also
come from within.
And just knowing this helped me,
for example, when I sometimes
wake up too early,
and I start to worry and wander
around with my thoughts.
Then I think, “Stop.
What did I eat yesterday?
Did I stress myself out too much?
Did I eat too late or something?”
And then maybe get up
and make myself a tea,
something light to digest.
And as simple as that sounds,
I think it’s been
surprisingly good for me.
Step three took me further
away from our body,
and to really understanding
The research we have today
is creating a new definition
of what real cleanliness is.
And it’s not the hygiene hypothesis —
I think many maybe know this.
So it states that when you have
too little microbes in your environment
because you clean all the time,
that’s not really a good thing,
because people get more allergies
or autoimmune diseases then.
So I knew this hypothesis,
and I thought I wouldn’t learn so much
from looking at cleanliness in the gut.
But I was wrong.
It turns out,
real cleanliness is not about
killing off bacteria right away.
Real cleanliness is a bit different.
When we look at the facts,
95 percent of all bacteria on this planet
don’t harm us — they can’t,
they don’t have the genes to do so.
Many, actually, help us a lot,
and scientists at the moment
are looking into things like:
Do some bacteria help us clean the gut?
Do they help us digest?
Do they make us put on weight
or have a lean figure
although we’re eating lots?
Are others making us feel more courageous
or even more resilient to stress?
So you see, there are more questions
when it comes to cleanliness.
And, actually, the thing is,
it’s about a healthy balance, I think.
You can’t avoid the bad all the time.
This is simply not possible;
there’s always something bad around.
So what really the whole deal is
when you look at a clean gut,
it’s about having good bacteria,
enough of them,
and then some bad.
Our immune system needs the bad, too,
so it knows what it’s looking out for.
So I started having this different
perspective on cleanliness
and a few weeks later,
I held a talk at my university,
and I made a mistake by 1,000.
And I went home and I realized
in that moment,
I was like, “Ah! I made
a mistake by 1,000.
Oh God, that’s so much,
and that’s so embarrassing.”
And I started to think about this,
I was like, “Ugh!”
And after a while I said,
“OK, I made this one mistake,
but then I also told so many
good and right and helpful things,
so I think it’s OK, you know?
It’s a clean thing.”
And then I was like, “Oh, wait.
Maybe I took my perspective
on cleanliness further.”
And it’s my theory at the moment
that maybe we all do.
Take it a bit further than just
cleaning our living room,
where maybe we make it
to sort like a life hygiene.
Knowing that this is about
fostering the good
just as much as trying to shelter
yourself from the bad
had a very calming effect on me.
So in that sense,
I hope today I told you
mostly good and helpful things,
and thank you for your time,
for listening to me.