WEBVTT

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Trillions of bacteria, viruses, and fungi
live on or inside of us,

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and maintaining a good, balanced 
relationship with them

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is to our advantage.

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Together, they form the gut microbiome,

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a rich ecosystem that performs a variety
of functions in our bodies.

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The bacteria in our guts
can break down food the body can't digest,

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produce important nutrients,

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regulate the immune system,

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and protect against harmful germs.

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We don't yet have the blueprint

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for exactly which good bacteria 
a robust gut needs,

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but we do know that it's important
for a healthy microbiome

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to have a variety of bacterial species.

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Many factors affect our microbiomes,

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including our environment,

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medications like antibiotics,

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and even whether we were delivered
by C-section or not.

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Diet, too, is emerging as one 
of the leading influences

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on the health of our guts.

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And while we can't control all 
these factors,

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we can manipulate the balance
of our microbes

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by paying attention to what we eat.

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Dietary fiber from foods like fruits, 
vegetables, nuts, legumes, and whole grains

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is the best fuel for gut bacteria.

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When bacteria digest fiber,

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they produce short chain fatty acids
that nourish the gut barrier,

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improve immune function,

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and can help prevent inflammation,
which reduces the risk of cancer.

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And the more fiber you ingest,

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the more fiber-digesting bacteria
colonize your gut.

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In a recent study, scientists exchanged
the regular high-fiber diets

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of a group of rural South Africans

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with the high-fat, meat-heavy diets
of a group of African-Americans.

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After just two weeks on the high-fat,
low-fiber, Western-style diet,

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the rural African group showed
increased inflammation of the colon,

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as well as a decrease of butyrate.

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That's a short chain fatty acid thought
to lower risk of colon cancer.

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Meanwhile, the group that switched
to a high-fiber, low-fat diet

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had the opposite result.

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So what goes wrong with our gut bacteria 
when we eat low-fiber processed foods?

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Lower fiber means less fuel
for the gut bacteria,

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essentially starving them 
until they die off.

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This results in less diversity

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and hungry bacteria.

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In fact, some can even start to feed
on the mucus lining.

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We also know that specific foods 
can affect gut bacteria.

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In one recent microbiome study,

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scientists found that fruits,

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vegetables,

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tea,

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coffee,

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red wine,

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and dark chocolate

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were correlated with 
increased bacterial diversity.

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These foods contain polyphenols,

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which are naturally occurring 
antioxidant compounds.

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On the other hand,

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foods high in dairy fat,

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like whole milk, and sugar-sweetened sodas

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were correlated with decreased diversity.

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How food is prepared also matters.

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Minimally processed, fresh foods
generally have more fiber

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and provide better fuel.

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So lightly steamed,

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sautéed,

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or raw vegetables

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are typically more beneficial
than fried dishes.

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There are also ways of preparing food
that can actually introduce good bacteria,

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also known as probiotics,
into your gut.

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Fermented foods are teeming
with helpful probiotic bacteria,

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like lactobacillus

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and bifidobacteria.

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Originally used as a way 
of preserving foods

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before the invention of refrigeration,

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fermentation remains a traditional
practice all over the world.

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Foods like kimchi,

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sauerkraut,

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tempeh,

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and kombucha

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provide variety and vitality
to our diets.

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Yogurt is another fermented food that can
introduce helpful bacteria into our guts.

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That doesn't necessarily mean that
all yogurt is good for us, though.

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Brands with too much sugar
and not enough bacteria

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may not actually help.

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These are just general guidelines.

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More research is needed before 
we fully understand

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exactly how any of these foods
interact with our microbiomes.

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We see positive correlations,

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but the insides of our guts are difficult
places to make direct observations.

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For instance, we don't currently know

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whether these foods are directly
responsible for the changes in diversity,

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or if something more complicated
is happening.

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While we're only beginning to explore
the vast wilderness inside our guts,

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we already have a glimpse of how crucial
our microbiomes are for digestive health.

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The great news is we have the power
to fire up the bacteria in our bellies.

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Fill up on fibers,

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fresh and fermented foods,

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and you can trust your gut
to keep you going strong.