This research paper shows how extensively our thoughts and emotions affect our intestines, and as a result, are actively involved in irritable bowel syndrome.

Their conclusion is that helping people to be aware of their emotional state, and to learn how to modulate feelings and thoughts, will assist people to manage the symptoms of IBS.

And we already know that our emotions affect our insides. We say "I had a gut feeling about it", and we feel sick when we are anxious.