Question: how does health of gut affect your mental health?

Ciarán O'Brien answered on 10 Nov 2014:

We’re still not sure of all the details, but we have discovered a few ways gut health affects your brain:

The vagus nerve is a direct link from the gut to the brain. It’s a really big nerve, that covers most of your intestines and allows communication between your gut and brain. We call it the brain-gut axis.

Some bacteria can affect the vagus nerve directly by secreting chemicals that affect it. They produce chemicals that are nearly identical to the neurotransmitter chemicals found in our brains, like serotonin and acetylcholine, which are very important in controlling our moods, our memory and our muscle movements.

Bacteria can also affect the brain indirectly by causing problems in the gut. If the bacteria trigger an immune response from your body, you’ll end up with inflammation of the intestines, which is painful enough, but the inflamed gut will also send signals through the vagus nerve to the brain to say that something is wrong. Crohn’s Disease is an example where the gut becomes inflamed and doesn’t calm down, and people with Crohn’s end up feeling a lot of visceral pain, which is when you feel pain, but you can’t really nail down WHERE you’re hurting, and that can cause your mental health to suffer.

There was a paper published by scientists in Norway just a few months ago where they looked into the bacteria that live in the gut of depressed people and compared it to the gut bacteria of non-depressed people. There ARE differences, so it looks very much like the bacteria in your gut can affect depression. They don’t CAUSE the depression, but they contribute to it in some way. I’m hoping to discover how they contribute in my own studies.