What keeps the microbiota in our gut from growing infinitely and taking over our body?

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What keeps the microbiota in our gut from growing infinitely and taking over our body?

In: Biology

Our immune system. Once we’re dead and there’s no more immune system, they do grow and eat our bodies.

I heard that there’s actually more Jon human than human cells in a human body. No idea if that’s true though.

There’s just no mechanism that would allow them to take you over. In the other hand viruses take over cells to reproduce.

I mean, they “grow infinitely”, keep feeding on the nutrients coming down through the intestines, and they multiply. And periodically your large intestine extracts the water and “compacts” everything, and then you poop the microbiota out. That’s what poop is.

They are too big to pass through the intestinal wall into your blood, and any that do are killed by the immune cells in your blood.

People already mentioned the immune system, the intestinal walls and defecation, but there’s also another mechanism: each other. There are hundreds of different bacteria in your intestines, and they all compete more or less equally for resources, preventing each other from growing out of control (and invasive pathogens from growing at all).

This is also why if you kill off a portion of your gut microbiota (e.g. with antibiotics), or move it somewhere with less competition (and without evolved mechanisms to control bacteria), the usually helpful bacteria do grow out of control and cause problems as an invasive species.