Have you ever had ‘butterflies’ in your stomach before a big event? Or experienced a change in your appetite or bowel habits when you’re stressed? These are just a few of the many ways that stress can affect your digestion. 

Your brain and your digestive system are in constant and close communication with each other. They communicate through three different nervous systems – the parasympathetic, sympathetic & enteric nervous systems. 

The parasympathetic nervous system controls processes in the body such as digestion, repair and relaxation. When the parasympathetic nervous system is dominant in the body it conserves energy, slows heart rate, increases digestion and relaxes sphincter muscles in the digestive tract. 

The sympathetic nervous system is responsible for the ‘fight or flight’ response experienced in answer to stress, and stimulates blood-flow to the major muscles and brain. 

The enteric nervous system is often seen being referred to as ‘the second brain’. It is an extensive nervous system found within the digestive system which controls its function. 

In response to stress our bodies may often initiate a ‘fight or flight’ response. During a ‘fight or flight’ response pupils can dilate, sweating may increase, heart rate can accelerate, and the peristaltic movement normally seen through our digestive system is often decreased. This is because the body is trying to ensure our survival. Part of the way it does this is by shunting blood and energy to the muscles and brain and away from the digestive system - slowing any functions that are not seen as essential to immediate survival. 

When we experience stress, and a ‘flight or fight’ response is activated, our digestive system can be significantly affected. The sympathetic nervous system moves blood away to other organs, interferes with the regular contractions of the muscles along the digestive tract and decreases secretions needed for proper digestion. 

These changes in the function of the digestive system due to stress may result in spasms through the digestive tract and an increase in the amount of acid present in the stomach – causing indigestion and burning sensations, and irritation of the large intestine which may lead to symptoms such as diarrhoea, constipation, cramping and bloating. 

Stress can have other effects on the digestive system. It may cause an increase in intestinal permeability and may also have an influence on gut flora – increasing bacterial adherence and decreasing levels of beneficial bacteria such as Lactobacilli