Eli5 – How does stomach anxiety work?


How can anxiety cause nausea or IBS

In: 1

Good question!

Anxiety puts your body into ‘fight/flight’ mode, which is the sympathetic nervous system. This means your body is adapting your body to move quickly, which is why you breathe faster and your heart rate goes up.

Well, what do you not need while running from a bear or a particularly angry grandmother? Your stomach. So your body inhibits your stomach muscles, causing the stomach contents not to move as much, which may lead to nausea, especially if you had a large, spicy, or fizzy meal.

I’m not too sure about IBS, as I would assume that the bowel muscles would also be inhibited. Perhaps contents staying still in your bowels lets the bacteria eat more, leading to gas/diarrhea?

I hope this helps!

I feel like this is a tough question to answer like you are five years old because as a whole given that we are just starting to understand how the gut plays into our psychology. Most of your body’s [serotonin resides in the gut](https://my.clevelandclinic.org/health/articles/22572-serotonin), which some have even gone as far as calling our “[second brain](https://hms.harvard.edu/news-events/publications-archive/brain/gut-brain).” I’m not sure the evidence for that is complete, but hopefully, someone will come along and correct/annotate what I’ve said.

Also, as mentioned, the basic “fight or flight” function can also be the cause of it in the short term, as others have noted. Adrenaline would be the significant contributing factor in this context.

tl;dr: We have biochemical feedbacks in our physiology that respond to environmental factors in different ways, and there is no definitive answer that encompasses all cases.

Going for the 5yo part!

Going back in evolution a bit, we were all dumb animals. One of the best things we could learn is what food is healthy and what might poison us.

The result is that our digestive system has a LOT of nerves that have a hotline to our brain.

And sometimes the signals can backfire. When our brain gets nervous, or dizzy, then it can send an overload of signals to the gut and we can’t really tell if we need energy or should evacuate the food we have.