Gut microbiome · your second genome

Story

Connected to · 3

synergy · 1

Urolithin A
The ellagitannins in pomegranate and similar foods become urolithin A only through particular gut bacteria that some people have; without those bacteria, eating pomegranate does not produce the molecule.

regulates · 2

Carbs & Fiber
What a fiber does depends not on whether it is soluble or insoluble but on two independent properties, viscosity and fermentability: fiber that bacteria can digest is fermented into short-chain fatty acids, while fiber they cannot digest but that is viscous forms a gel in the gut.
IBS
The low-FODMAP diet, which temporarily cuts a group of short-chain carbohydrates that ferment easily in the gut and produce gas, is a time-limited diagnostic diet; the 2021 ACG guideline gives it a conditional recommendation based on very low-quality evidence. It should be done briefly under a dietitian's guidance, with foods added back one at a time; followed strictly for a long time, it may end up starving the gut microbes.

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What gut bacteria do for you

EVIDENCEREVIEW 3 · COHORT 1

READ THE ORIGINAL

Some of what you swallow is not yours to digest.

Your large intestine is home to tens of trillions of microbes, weighing about 200-500 g together, roughly a small bag of rice. They form a whole working ecosystem, and their most important job is digesting the fiber you cannot break down yourself. Fiber slides through the small intestine to the colon, where the microbes ferment it into short-chain fatty acids. One of them, butyrate, is eaten directly by the cells of the colon wall: well-fed wall cells pack tightly together, and the barrier holds.

The microbes also give your immune system daily practice, and some of their products travel along the vagus nerve and through the blood to reach the brain, a route called the gut-brain axis. So building a healthy microbiome comes from feeding it fiber and many kinds of plants, not from a single supplement.

If you have bloody or black stools, or weight loss you cannot explain, see a doctor now; do not treat it as a microbiome that needs work.

Watch this step as a mechanism animationOpen mechanism

Educational content, not medical advice — consult a clinician.

Back

Gut microbiome · your second genome

Story

Connected to · 3

synergy · 1

Urolithin A
The ellagitannins in pomegranate and similar foods become urolithin A only through particular gut bacteria that some people have; without those bacteria, eating pomegranate does not produce the molecule.

regulates · 2

Carbs & Fiber
What a fiber does depends not on whether it is soluble or insoluble but on two independent properties, viscosity and fermentability: fiber that bacteria can digest is fermented into short-chain fatty acids, while fiber they cannot digest but that is viscous forms a gel in the gut.
IBS
The low-FODMAP diet, which temporarily cuts a group of short-chain carbohydrates that ferment easily in the gut and produce gas, is a time-limited diagnostic diet; the 2021 ACG guideline gives it a conditional recommendation based on very low-quality evidence. It should be done briefly under a dietitian's guidance, with foods added back one at a time; followed strictly for a long time, it may end up starving the gut microbes.

Read full story

Stop 1/5

What gut bacteria do for you

EVIDENCEREVIEW 3 · COHORT 1

READ THE ORIGINAL

Some of what you swallow is not yours to digest.

Your large intestine is home to tens of trillions of microbes, weighing about 200-500 g together, roughly a small bag of rice. They form a whole working ecosystem, and their most important job is digesting the fiber you cannot break down yourself. Fiber slides through the small intestine to the colon, where the microbes ferment it into short-chain fatty acids. One of them, butyrate, is eaten directly by the cells of the colon wall: well-fed wall cells pack tightly together, and the barrier holds.

The microbes also give your immune system daily practice, and some of their products travel along the vagus nerve and through the blood to reach the brain, a route called the gut-brain axis. So building a healthy microbiome comes from feeding it fiber and many kinds of plants, not from a single supplement.

If you have bloody or black stools, or weight loss you cannot explain, see a doctor now; do not treat it as a microbiome that needs work.

Watch this step as a mechanism animationOpen mechanism

Educational content, not medical advice — consult a clinician.