62 | March• 2018
GUT BACTERIA THE NEW FRONTIER OF SCIENCE
A
nyone who has
had an anxious
knot in their stomach
knows that the gut
and mood are related.
That’s partly due
to the vagus nerve,
a nerve that runs
directly from the gut
to the brain. Studies
suggest that the
brain and gut are in
constant dialogue,
communicating using
the nervous system
as well as the blood
stream and hormones.
There’s mounting
evidence that the
composition of
bacteria species in the
gut is also linked to
changes in the brain’s
structure and how it
functions. Scientists
think the metabolites
produced by thegut bacteria enter
the blood and can
cause inflammation,
contributing to
brain diseases such
as Parkinson’s,
Alzheimer’s and
autism. People with
mental illnesses such
as depression, anxiety
and schizophrenia
have all been shown
to have dramatically
different gut bacteria
to those found in a
healthy gut.
It appears the gut
microbiome can affect
behaviour, too. A
Canadian study using
mice has shown that
exposure to antibiotics
can affect the brain,
causing changes to the
blood–brain barrier
and other changes in
the frontal cortex. Theyoung mice became
more aggressive and
their social interaction
changed compared
to mice whose gut
bacteria had not been
exposed to antibiotics.
When they were given
probiotics as well as
antibiotics, there were
fewer changes to their
brains and behaviour.
It’s still not clear
why the gut affects
the brain in this
way, but we know
that serotonin, the
chemical associated
with mood, is mostly
produced in the gut.
It’s also thought
that the bacteria’s
metabolites can
affect the chemistry
of the brain, affecting
human mood and
behaviour.TERIA – THE NEW FRONTIER OF SCIENCEGUT BACTERIA AND
the Brain