It’s All About Bacteria
Generally when we think about what our immune system deals with, we think about viruses and pathogens and all those nasty things on airplanes and in our kid’s kindergarten classes.
But the truth is, dealing with a pathogen is a rare thing for our digestive immune system. Most of its energy is spent managing our microflora - those beneficial bacteria we pop probiotics and eat yoghurt to encourage. We need them for our health. We just also need them to stay in our gut because they aren’t so beneficial inside our bodies.8,9,10,11
If you’re wondering how big a role these bacteria play, remember there are more cells in our microflora than cells in our own bodies.
They are so important in fact that several researchers proposed that our digestive immune system evolved not because of pathogens but to allow us to live in harmony with our microflora.5,9,11,12
This is a critical distinction!
If a pathogen or even the normally healthy bacteria in our gut gets into our blood, our bodies mount an immediate and strong inflammatory response.13,14 This inflammation is what causes the aches, fever, and chill we associate with being sick.
The response to a bacterial infection in circulation, though damaging, is necessary and keeps us alive. Fortunately, bacteria rarely gets into our blood.
In the gut, on the other hand, the immune system is exposed to bacteria thousands of times each day. An inflammatory response every time would be deadly.5, 15 There’s even a name for this out of control inflammation – sepsis.16
As a result, the digestive immune system takes a very different tact with our beneficial bacteria. It becomes anergic - meaning it actually blocks inflammation.17,18 Special immune cells in the gut called T regulatory (Treg) cells and a unique type of APC cell actively shut down the inflammatory response and then quietly take out the invading bacteria one-by-one.3,15
References
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