How does my nervous system affect my digestive system?

One of my clients came in recently with a flare of his IBS symptoms. This person reported pain in his hip as well as his lower back during his IBS flares. He also noted that the previous week had been very stressful at work. I mentioned that his stress level might be related to his increase in symptoms. And he asked me how. Here is a bit of my response.

Our digestive system is very closely connected to our nervous system. The fight or flight system is directly opposite from our rest and digest system. And while we're never completely in one side or the other of our nervous system we tend to be closer to one end or the other most of the time. Ideally, we want to have times where we go up into fight or flight and then come back down to rest and digest. This is the normal functioning of our nervous system when we have prolonged periods of fight or flight, which tends to cause problems.

In this person's case, he reported that when he would eat, it was followed immediately by explosive diarrhea and an upset stomach with cramping and bloating. I mentioned to him that when our bodies are in a fight or flight state, it's not really in a state to be able to accept and digest food. When we're in fight or flight, our blood is shunted to our skeletal muscles in case of emergency. It's preparing our body to be able to fight flight or freeze.

When our body is in the fight or flight state, it will do one of two things. Our bodies will either expel all the food in our digestive system, thereby eliminating excess weight to allow our body to flee or fight, or it will hold on to that food, which will sit longer in our digestive tract, contributing to things like upset stomach, gas, bloating, and constipation. This occurs because our body has decided to decrease the blood flow and the energy flow to our digestive system and instead shunts the resources to our musculoskeletal system for protection to allow for escape.

Through our physical therapy sessions, we worked on decreasing some of the sympathetic nervous system drive during stressful events, and then for homework, he was given some exercises to do to prepare his body for the work of digestion before eating to get his nervous system and digestive system in a state that could accept and digest food. If this sounds like something you're struggling with, visceral manual therapy might be something that helps.