READER’S DIGESTDECEMBER 2021 • 37look when you’re an adult. The
different types of bacteria that live in
your gut can help you digest food, but
they also impact other aspects of your
body, including your immune system,
brain, and your cardiovascular health.
“Your gut is like its own
ecosystem,” says Sean Gibbons, a
microbiome researcher and assistant
professor at the Institute for Systems
Biology in Seattle, Washington.
“It’s warm, humid, and wet—like a
rainforest.” And, he explains, like any
thriving ecosystem, your gut is
healthy when it’s diverse, with
hundreds of types of bacteria.
Two of the most important are
Firmicutes and Bacteroidetes, which
feast on dietary fibre and break down
complex carbohydrates. Both also
churn out short-chain fatty acids,
microscopic compounds that help
maintain the integrity of the gut wall
(that barrier is supposed to be porous
in order to let nutrients through, but if
it’s too porous, that can lead to
inflammation). They also have anti-
inflammatory properties and can
promote brain health.
You should feed those two types
well, because if there’s not enough
food in your system, they’ll turn to a
secondary source of nutrients. “They
will actually start to eat your gut
mucus,” explains Gibbons. If that
happens, many bacteria in your gut
will suddenly be seen by your
immune system as outside agents,
setting off a response that can lead to
inflammatory bowel disease and other
gut problems.SIGNS YOUR GUT
IS OUT OF BALANCEYou have a stubborn
bowel condition
Crohn’s disease and ulcerative colitis—
known together as inflammatory
bowel disease (IBD)—cause
inflammation and breaks in the lining
of the intestines, leading to pain,
diarrhea, and weight loss. It affects
less than one per cent of Europeans.
Dr Eugene Chang, director of the
Microbiome Medicine Programme
at the University of Chicago, says its
exact cause is unknown. But, he adds,
researchers believe affected people
are genetically predisposed to an
overactive immune system, and that
their microbiome changes in subtle
ways to prefer bacteria that thrive in
that inflammatory environment.
“Those bacteria further activate the
immune system. It’s a vicious cycle
that eventually triggers IBD.”
IBS, which is much more common
and affects up to 11 per cent of
people worldwide, shares many
symptoms with IBD but without the
inflammation and ulcerations. Like
IBD, the exact cause of IBS isn’t yet
clear, but studies have shown
differences in the microbiome of
IBS patients—and probiotics can
help some of them feel better.