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Translator: Rhonda Jacobs
Reviewer: Ellen Maloney
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Imagine this...
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You have just won
ten million dollars in the lottery.
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Congratulations.
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(Laughter)
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You have just eaten the most delicious,
warm, chocolate brownie
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that has ever been baked.
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(Laughter)
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You...
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have just had sex.
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(Laughter)
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And you...
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have just done all three at the same time.
Congratulations to you, too.
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(Laughter)
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In these situations, our brains
produce chemicals called neurotransmitters
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which give us these great feelings
of energy, excitement and happiness.
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And without such chemicals inside of us,
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we wouldn't feel such emotions
during such pleasant circumstances.
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So instead, imagine this:
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You've just been fired.
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You're about to sit an exam.
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You have depression.
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In these situations, our brains, instead,
produce different chemicals,
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making us feel stressed and anxious.
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The highs and lows of life
are controlled by our emotions
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and these chemicals in our brains.
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This vital organ inside all of us
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that controls everything
that we feel, think and do.
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However, as a biologist, I've always
found it strange to comprehend
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that every feeling, thought,
and action that we have
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is controlled by a three-pound,
soggy lump of cells inside of our heads,
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until I discovered
that this might not be the case.
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The story I want to share with you today
unfolds a fascinating new revelation
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in our understanding of human physiology,
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that we each have a second brain,
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another organ in our body
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which controls as much
of our physical and mental functions
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as the brain in our heads,
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and which may be the key link between
modern disease epidemics, globally,
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from obesity to cardiovascular disease,
maybe even to mental health.
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But first, to give you a little
introduction to this story,
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I want to tell you a little bit
about my background.
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I was brought up
in a family of psychologists.
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My mom is a clinical psychologist;
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my dad a professor
of psychology in a university;
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my sister even has a PhD in psychology.
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So when it came to me going to university,
I wanted to study something different.
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I'd heard enough about the brain
and how it worked at home
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so I wanted to study something new.
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I considered what I was interested in,
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and I figured out
that from a very early age,
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I'd had a big interest in food.
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I loved eating food.
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So, I decided to study human nutrition.
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And this was great
because I got to study food,
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how it affected our bodies,
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how it could contribute to disease,
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and more importantly, how we could use it
to fight and prevent disease.
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This story begins back in 1845
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with the birth of a curious
young boy in Russia
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who became an incredible man,
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but who was forgotten
by history and medicine.
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Ilya Mechnikov was fascinated
by everything in nature,
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and by the age of eight,
he was taking notes
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on all the living things
in his vibrant back garden.
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He became so good at science
that he discovered the role of phagocytes,
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some crucial cells in our immune systems,
for which he won the Nobel Prize in 1908.
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But it was his science
after winning the Nobel Prize
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that was even more crucial
to our understanding of human health,
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through a tale of discovery, death,
and self-experimentation.
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See, everyone in this room
has something in common.
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We all spent the first
nine months of our existence
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inside our mothers' wombs.
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And this was essentially
a sterile environment
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where no other living things
existed, just you.
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But as you emerged into this world,
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you were smothered
in an invisible coating of microbes,
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friendly microbes
from your mother's birth canal.
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And these bacteria grew
to form what is now
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a three-pound invisible organ
inside your large intestine,
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the same weight as your brain,
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and which has become known
as our microbiota, or microbiome.
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And this invisible organ
has grown so much, in fact,
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that right now, 90 per cent of the cells
in your body are bacterial cells;
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only ten per cent
are your own human cells.
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So you are more bacteria
than you are human.
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(Laughter)
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This ecosystem of microbes in your gut
is as diverse as the Amazon rainforest.
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Thousands of species
all with different functions.
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And your health is incredibly dependent
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upon the life and vibrancy
of this rainforest.
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Your gut bacteria digest certain foods,
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produce essential vitamins and hormones,
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respond to medicine and infections,
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control your blood sugar
and blood cholesterol levels.
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Meaning the types
of bacteria in your intestines
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can significantly control
your risk of certain diseases
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from obesity to diabetes,
maybe even osteoporosis.
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They're involved in just about
every process in your body.
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They function almost as a second brain.
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Well, Ilya Mechnikov may have
figured this out himself in 1892.
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He lived in France, in Paris at the time,
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where a deadly cholera
epidemic had broken out
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with thousands of deaths.
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Naturally, as a scientist, he decided
the best way to study this
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was to drink a broth of cholera himself.
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Remarkably, he didn't get sick.
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So again, as a true scientist,
he needed to increase his sample size,
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so he recruited a colleague
to do the same thing.
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This guy didn't get sick either.
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But when he recruited
another colleague to do the same,
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this poor guy got critically ill
and very nearly died.
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By studying cholera under the microscope,
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Metchnikov found that certain species
of bacteria from the human intestines
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supported and stimulated cholera's growth,
while other species prevented it.
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He subsequently claimed that our gut
microbiota, or our gut bacteria,
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were essential for human health,
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and that the right balance
of microbes inside of us
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could help stave off disease.
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However, popular
understanding at the time,
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was that the human gut
was a noxious reservoir of toxins.
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Surgeons had even begun removing
entire sections of human intestines
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in patients with gut discomfort.
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Mechnikov's death in 1916
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meant that his ideas that our gut
bacteria were good for us were forgotten.
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A decade later,
antibiotics were discovered,
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and drastically became overused.
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C-sections became common.
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Diets became Westernized.
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A war was waged on microbes and we spent
a century trying to kill them,
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which turned our intestinal rainforests
into barren wastelands.
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This Nobel Prize winner's ideas
were lost in time.
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Some of the implications of this
were identified recently.
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See, right now, one in three children
in America are born by C-section,
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meaning they don't get this initial
innoculum or coating of bacteria
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that's been designed by evolution
to be in the mother's birth canal.
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Instead, they're first coated
with other bacteria on the skin
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or in the hospital environment
which has contributed
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to up to a 25 per cent
increased risk of obesity,
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asthma, immune deficiencies
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and inflammatory
bowel disease in later life.
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Fortunately, in recent times,
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we've realized we must
restore our relationship
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with gut microbes
for our own physical health.
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However yet, we've still
completely underestimated
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their role as our second brains.
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And this is something
that I'm researching.
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And I learned this first
through the intriguing story of a mouse.
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If mice become colonized
by the microbe Toxoplasma gondii,
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an intriguing thing happens:
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they lose their fear of cats.
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(Laughter)
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In fact, they become attracted to cats.
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(Laughter)
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In essence, they go a bit mad,
and unfortunately for them,
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usually end up as dinner for cats.
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(Laughter)
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So, this microbe ingested by this animal
takes control of its brain,
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and changes the way
that it thinks and behaves.
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So, by delving deep inside the intestinal
jungle of bacteria in our intestines,
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we've begun to find
some incredible discoveries
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that are changing our appreciation
for bacteria forever.
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See, our bellies and brains
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are physically and biochemically
connected in a number of ways.
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First of all, our intestines
are physically linked to our brain
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through the vagus nerve
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which sends signals in both directions.
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Interestingly, even though
if this is severed,
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our intestines can still
continue to function fully
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without a connection to the brain,
suggesting they have a mind of their own.
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Secondly, our brains are made up
of a hundred billion neurons
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which continuously send messages
to tell our bodies how to work and behave.
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Well, interestingly, our guts
have a hundred million neurons.
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Thirdly, our microbiomes
are the centerpoint of our immune systems,
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meaning a disturbance down here
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can cause subtle immune reactions
all around the body,
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which if prolonged,
can affect brain health.
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And finally, do we remember
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our chocolate-eating, lottery-winning
womanizer here in the front row?
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He demonstrated for us
the neurotransmitters
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are these chemicals that can change
the way we think and behave,
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and how we feel.
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As it turns out,
most of these neurotransmitters
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are also produced in our gut,
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none more so than serotonin,
nature's antidepressant,
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90 per cent of which
is produced in our intestines,
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less than ten per cent
is produced in our brains.
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Meaning the types
of bacteria inside of you
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may control the way
that you think and behave.
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Has stress ever messed with your insides?
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Have you ever had a gut feeling?
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Or butterflies in your stomach?
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You may have to think twice about that.
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So, you can see, despite my naive
reluctance as a teenager,
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I've begun to study not only
one brain, but two brains.
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In the APC Microbiome
Institute in Ireland,
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we're fascinated in this link
between our belly and our brains,
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and we research how
our modern diets and lifestyles
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are impacting this gut-brain relationship,
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and how we can design interventions
to target the microbiota
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in order to prevent
and treat chronic diseases.
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For example, we've shown
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that the types of fats
that you eat throughout life
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can drastically change
the types of bacteria
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that decide to reside in your intestines.
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In addition, we've shown that by feeding
specific strains of bacteria,
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it can enhance memory, stress behavior,
and stress hormone levels in animals.
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And in addition to a number
of other researchers worldwide,
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we've identified lists of foods
that can act as prebiotics,
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or foods that can stimulate the growth
of healthy bacteria inside our intestines.
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To me it's fascinating
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that our health is so dependent
not only upon nourishing ourselves,
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but upon feeding other living
microorganisms inside of us,
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meaning future strategies
to target and treat chronic diseases,
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including brain health, may depend
on targeting or feeding
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our gut microbiomes.
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As it turns out, Ilya Mechnikov
may have known this himself.
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See, much earlier in his life he married,
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but his wife quickly became sick
with tuberculosis and died.
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The stress and trauma of this
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led Metchnikov to take
an overdoes of opium.
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Thankfully, he survived.
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He then re-married,
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and when his second wife got sick
with the deadly typhoid fever,
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this time he injected himself
with a deadly tick-borne disease.
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Thankfully, he survived again.
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It was only after this,
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Metchnivok began studying
and appreciating the microbiota.
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He moved to Paris
to work in the Pasteur Institute
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where he began hypothesizing
the right balance of microbes in the gut
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could help stave off disease,
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and he published a series
of books and lectures
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describing how to achieve this
and prolong life.
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Despite the stress and mental turmoil
that he'd experienced in earlier life,
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he spent the rest of his life
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dedicated and obsessed with
researching how to prolong human life.
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He began studying an interesting group
of people in Eastern Europe
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who were living exceptionally long lives,
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and he noted that they all drank
bacterial-fermented milk every day
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and he suggested that
this contributed to their longevity.
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Interestingly, he began drinking
this bacterial-fermented milk himself,
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and seemingly lived a healthy life
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rid of the stress and mental turmoil
he'd experienced in earlier life.
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Maybe that was just coincidental.
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He described the time in Paris
as the happiest of his life.
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But Metchnikov died in France
in 1916 at the age of 71.
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The life expectancy
in France at the time was 40.
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As humans, we all need
to adopt a greater appreciation
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for the microbes inside of us.
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The incidental war we've waged
on bacteria over the last century
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has led to bacterial extinction
and sparked an epidemic of modern plagues.
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I'm here on a Fulbright
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to research how we can restore
our relationship with microbes,
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and how this can be used
to prevent and treat chronic diseases.
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But I feel that we all have
the responsibility and the potential
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to follow in Ilya Metchnikov's footsteps.
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Not only to revive his scientific findings
that were lost in time,
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but to adopt his desire
to prolong healthy, human life.
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Whether it's by educating ourselves
on the risks and benefits of C-sections,
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restricting unnecessary antibiotic use,
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or by adopting a gut-friendly
diet and lifestyle,
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we can all support the life of microbes
that we've evolved to live alongside.
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So imagine this:
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Imagine you've just eaten chocolate,
or won the lottery,
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sat an exam or just been fired.
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Imagine your thoughts, your emotions,
your behavior, and your health
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could be controlled by a hidden organ
that you knew little about.
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Ilya Metchnikov fought to not only
prolong healthy human life,
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but healthy microbial life.
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I feel we can all contribute
to this fight worth fighting
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for our own health, but more importantly,
for future generations' health
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by restoring the relationship
between microbe and man.
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There is some food for thought.
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Thank you very much.
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(Applause)
