Irritable Bowel Syndrome

The What, Why and How

Irritable bowel syndrome, or IBS, is the most common functional digestive disorder.  Generally, digestive problems fall under two categories, functional and pathological.  Pathological disorders are basically those that can be seen and/or measured such as tumors, ulcers and others.  The vast majority of testing that is done for digestive complaints is done to look for pathologies.

Functional disorders, in contrast, are diagnosed by the presence of symptoms combined with the absence of pathology.  Generally, they can be described as some phase of the digestive process simply not “functioning correctly”.  They are often diagnosed by ruling out pathology in the presence of symptoms rather than demonstrating some abnormality.  As with many “rule out” diagnoses, the patient is often left only knowing that they have no pathology but without getting answers about what needs to be done to resolve the symptoms.

It is estimated that 80% of digestive disorders are functional and only 20% are pathologic. IBS is the most common functional digestive disorder.  Between 10-15% of the population experiences IBS.  The typical symptoms include abdominal pain, bloating, and often constipation and/or diarrhea. They may vary from episode to episode. 

The most important point to appreciate regarding IBS is that it is a heterogeneous disorder.  This simply means that it is not caused by one thing but rather can be caused by several problems.  The most important point in resolving any individual case is to find all of the triggers in that circumstance.  IBS is also typically “multifactorial” which means it is caused by several contributing factors.

Occasionally, it will be just one factor such as a food sensitivity.  Most often, however, it results from the co-existence of multiple factors in the same person. Appreciating this relationship is the most important factor in obtaining resolution of the problem.

The two diagrams show the concepts of multifactorial and heterogeneous. Patient "A" has 4 contributing factors causing their IBS. While different ones are contributing more or less to the problem, resolution is unlikely to occur unless all are addressed.

In contrast to patient "A" the second example, patient "B" has a different grouping of factors causing their IBS (multifactorial), and they are not the same as patient "A's" triggers (heterogeneous).

These different triggers of IBS are not equally common.  Food sensitivities, or immune inflammatory food reactions, are perhaps the most common.  These are delayed food immune reactions with symptoms beginning from several hours to 1-2 days after the food exposure.  Typically, the person has eaten multiple times in between obscuring the relationship.

Dysbiosis is another common contributing trigger to IBS.  This is an imbalance in the bacterial population living in the digestive tract.  Certain species help with the regulation of inflammation in the digestive tract.  These species should make up the dominance of the population of the 100 trillion bacteria in the human microbiome.  Many factors may cause the favored species to diminish allowing less desirable “opportunistic” bacteria to populate.  This often causes a low grade inflammatory response instead of the inflammatory preventing response created by the preferred bacterial population.

Stress often is the most difficult for most to understand the relationship with IBS.  The autonomic nervous system that governs all function in the digestive tract has two divisions, the sympathetic which controls “fight or flight” and the parasympathetic which controls “rest and repair”.  Digestive function is shut down during fight or flight and activated when in rest and repair. 

Ongoing stress tends to train the nervous system to stay in sympathetic dominance inhibiting function in the digestive tract.  IBS cannot be fully understood without a look at the balance in the autonomic nervous system.  This can be done with a test called heart rate variability which shows the sympathetic/parasympathetic balance.  Once the problem is understood, autonomic training can be successfully used to retrain balance in sympathetic/parasympathetic tone.

IBS is truly multifactorial, heterogeneous.  Only approaching its diagnosis and treatment with this understanding will consistently yield good results.