The gut has a mind of its own, the "enteric nervous system". Just like the larger brain in the head, researchers say, this system sends and receives impulses, records experiences and respond to emotions. Its nerve cells are bathed and influenced by the same neurotransmitters. The gut can upset the brain just as the brain can upset the gut. We have all experienced a gut reaction.

The gut's brain or the "enteric nervous system" is located in the sheaths of tissue lining the esophagus, stomach, small intestine and colon. Considered a single entity, it is a network of neurons, neurotransmitters and proteins that zap messages between neurons, support cells like those found in the brain proper and a complex circuitry that enables it to act independently, learn, remember and, as the saying goes, produce gut feelings. 

The gut's brain is reported to play a major role in human happiness and misery. Many gastrointestinal disorders like colitis and irritable bowel syndrome originate from problems within the gut's brain, and they can also be made worse from anxiety. Many clients get very anxious about having IBS which then causes their IBS to become more severe.

The gut contains 100 million neurons - more than the spinal cord. Major neurotransmitters like serotonin, dopamine, glutamate, norephinephrine and nitric oxide are in the gut. Also two dozen small brain proteins, called neuropeptides are there along with the major cells of the immune system. Enkephalins (a member of the endorphins family) are also in the gut. 

As light is shed on the circuitry between the two brains, researchers are beginning to understand why people act and feel the way they do. When the central brain encounters a frightening situation, it releases stress hormones that prepare the body to fight or flee. The stomach contains many sensory nerves that are stimulated by this chemical surge - hence the "butterflies." On the battlefield (states of anxiety), the higher brain tells the gut brain to shut down. 

IBS therefore has a huge psychological aspect and is often seen in clients that are not outwardly stressed, they are thinkers and what if-ers. They internalise a lot and the gut reacts accordingly, IBS is essentially anxiety in the gut.
IBS is the commonest condition seen by gastroenterologists and some estimates suggest that as many as one in five of the adult population in the UK suffer from it at any one time.