This. It's so weird when you conclude your mind is having a direct and undeniable influence on your physical wellbeing.
In my case, I can't eat certain foods (I'm still trying to work out which, but it includes chocolate) when I'm stressed. I get severe cramps, bloating, pain and even hot flushes (intense sweating). It happened to me on a train once and people thought I was OD-ing.
And stressed doesn't mean "close to the edge". Just a bit of nerves about something, definitely not enough to keep me up at night, will do the trick.
When the evidence suggested chocolate made me really unwell, but only if I was a bit stressed, it was really hard to accept because it just sounds so weird and implausible.
It's not really surprising, as we already know that the gut is influenced by stress. The main pathways are the vagus nerve and the HPA axis, which control gastric emptying and colonic movement. Stress will either shut down your vagus nerve resulting in reduced stomach emptying, or it will activate the HPA axis and cause diarrhea (or both).
I get IBS myself, so I find it a little strange that some people don't. My guess is that my nervous system is simply more liable to over-activate than most people's. This is useful in that it gives me copious amounts of mental energy and ability to crank out amazing code very quickly and do stuff that most people (present company excepted) wouldn't be able to do, like design and build a compiler/VM for my own programming language, or build an HTML5 web conferencing system by myself. The downside is that I am prone to IBS and burnout.
While there is ample evidence of the brain influencing the gut, there isn't really much evidence of the gut influencing the brain. It seems unlikely that 'butterflies in the stomach' is caused by the gut influencing the brain, rather than the other way around. The afferent vagus nerves do signal to the brain when there is a gut infection, and that can certainly cause anxiety and depression. However most people with anxiety/depression/IBS don't have any active infection, and there is more evidence that it is the brain influencing the gut rather than the other way around. One possibility is that people with these conditions are genetically programmed to release more serotonin, and that happens both in the brain and the gut.
In my case, I can't eat certain foods (I'm still trying to work out which, but it includes chocolate) when I'm stressed. I get severe cramps, bloating, pain and even hot flushes (intense sweating). It happened to me on a train once and people thought I was OD-ing.
And stressed doesn't mean "close to the edge". Just a bit of nerves about something, definitely not enough to keep me up at night, will do the trick.
When the evidence suggested chocolate made me really unwell, but only if I was a bit stressed, it was really hard to accept because it just sounds so weird and implausible.