Although the cause of irritable bowel syndrome (IBS) has not yet been completely understood, multiple factors appear to have a role, including composition of the gut micro-flora, intestinal permeability, immune response and the gut-brain connection.
The gastrointestinal microflora is a diverse and numerous ecosystem that inhabits the entire gastrointestinal tract and has a systemic influence on our health.
Associations were observed between patients self-reported symptoms and the presence or quantities of certain gut bacteria. Among IBS subjects several gut bacterial strains were significantly reduced. (4)
Microflora activity is different between herbivorous and carnivorous mammals, reflecting trade-offs between carbohydrate and protein fermentation. Foodborne microbes from both diets periodically colonize the gut, including bacteria, fungi and even viruses. These facts demonstrate that the gut microflora can rapidly respond to altered diet. (6)
An imbalance of intestinal microflora and/or the presence of unwanted fungi, bacteria and viruses can disrupt the sensitive mucous membrane of the gut leading to inflammation.
On one hand, an intact intestinal barrier protects the human organism against invasion by micro-organisms and toxins, on the other hand, this barrier must be open to absorb essential fluids and nutrients.
Such opposing goals are achieved by very complex anatomy and physiology. The intestinal barrier represents a huge mucosal surface, where billions of bacteria face the largest immune system of our body. (3)
In one study the permeability of colon tissue samples was found to be significantly higher in patients with IBS compared to healthy subjects. (5)
This may be caused to disturbances to the microflora which in turn may have triggered an inflammatory immune response, resulting in a breakdown of permeable gut barrier.
Infectious gastroenteritis is the strongest risk factor for the development of IBS and increased rates of IBS-like symptoms have been detected in patients with inflammatory bowel disease in remission or in celiac disease patients on a gluten free diet. The number of immune cells in the small and large intestine of patients with IBS is increased in a large proportion of patients. (2)
Supporting the immune system and microflora of the gut may be of assistance, improving digestive processes while simultaneously reducing gut inflammation and permeability.
The brain, the gut, its microflora and the immune system present two way communications in health and disease. The brain, via the nervous system, influences intestinal motility and fluid secretion (8), intestinal permeability (3), immune function (10) and gut microflora (11), all of which have been reported to be out of control with IBS as previously mentioned.
The mental and emotional connection to the digestive system is powerful and must be considered in the context of IBS.
Technically known as the enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of the long tube of our gut, or alimentary canal, which measures about nine meters end to end from the esophagus to the anus.
The second brain contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system. (16)
The enteric nervous system uses more than 30 neurotransmitters, just like the brain, and in fact 95 percent of the body’s serotonin is found in the bowels.
Irritable bowel syndrome also arises in part from too much serotonin in our entrails, and could perhaps be regarded as a “mental illness” of the second brain. (16)
