The gut microbiome is a direct line of communication for the central nervous system and messages are constantly being sent between your brain and gut. This is called the gut brain axis. The gut is the site of mood regulating hormones such as serotonin and dopamine. A healthy gut plays a huge role in your mental health.
Stress affects your gut microbiome because of the role it plays in the bodies immune response. Your immune system is unable to distinguish between mental and physical stress, therefore the inflammatory response is activated, flooding your system with inflammatory cytokines which act as messengers. Chronic stress constantly activates this inflammatory response leading to chronic inflammation and disease. Having an imbalance of bad bacteria in the gut can contribute to the release of inflammatory cytokines, leading to more inflammation. Good bacteria in the gut can have the opposite effect, interacting with the immune system in a way that can reduce the stress response.
Massage therapy can play a role in your gut health by allowing your body to enter the parasympathetic nervous system. This is your bodies rest and digest mode and allows for the reactivation of the digestive system, which slows down during the stress response. This allows for restoration to occur in your gut microbiome and reduce the body's inflammatory immune response to stress. Massage can also help manage pain caused by chronic inflammation. Abdominal massage can assist digestion through the relaxation of sphincter muscles in the intestinal tract, increasing intestinal activity which in turn improves gut health.