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Causes of Irritable Bowel Syndrome three main pillars

Irritable bowel syndrome is a disease about which not much is known in 2016. It occurs more often in women than in men and may be related to abnormalities in intestinal motor skills, increased sensitivity of the nerves from the intestines and sometimes psychological factors. There is no drug treatment for it. The most important thing is to reduce stressors.

Causes of irritable bowel syndrome

Various pathophysiological mechanisms play a role in the development of irritable bowel syndrome (IBS). The three most important mechanisms are: abnormalities in small intestine and colon motor function, altered visceral perception (more sensitive nerves) and psychological factors (e.g. stress can change intestinal movements). Other factors can also play an important role, for example previous gastroenteritis. It is not yet clear to what extent the factors influence each other, but there is indeed an interaction (2016). Moreover, it is unclear whether these factors cause IBS or whether they are a consequence of it.

Abnormalities in small intestine and colon motor function

Diarrhoea, constipation and a feeling of incomplete defecation are symptoms that indicate that altered motor skills underlie the IBS. Manometric techniques showed that in some IBS patients there is an exaggerated increase in contractile movements of the small intestine after meals. In addition to this hyperreactivity, abnormal motor complexes have also been described, such as clustered contractions, alternating with motor rest. These clustered contractions can cause pain. Increased activity of intestinal movements leads to complaints such as gas formation and diarrhea. Reduced intestinal motor function leads to slow food passage and causes hard, dry stools and constipation.

Altered visceral sensitivity

A second factor that may play a role in the development of IBS is the increased visceral sensitivity of the digestive system. With altered visceral sensitivity, a normal, harmless stimulus may be experienced as painful (allodynia) or the threshold for a painful stimulus may be lowered (hyperalgesia). An altered perception can be found in approximately 90% of IBS patients. These people experience more pain than normal when the intestines are stretched by gas or stool. The regulation of the brain-gut axis works differently than normal, causing an overreaction to normal physiological changes in the intestines during digestion. There are a number of factors that may play a role in changes in the brain-gut axis:

  • A genetic predisposition to development of IBS
  • An intestinal infection prior to the onset of symptoms
  • Chronic stress or other psychosocial factors


Psychological factors

It has been known for years that stress can influence the motor skills of the gastrointestinal tract and it is becoming increasingly clear that psychosocial factors contribute to the development, worsening and persistence of IBS complaints (stress is mainly a contributing factor, and not an unambiguous cause of IBS). In particular, chronic stressors such as divorce, relationship problems and a serious illness can worsen the symptoms of IBS. The complaints of IBS can in turn also cause stress, which can create a vicious circle of stress and complaints. Furthermore, a higher comorbidity of psychiatric disorders has been found in IBS, such as anxiety and panic disorders and depressive disorders.

Symptoms of IBS

IBS complaints are very individual and are therefore different for everyone. The complaints in one patient are also often different from one time to another. The most characteristic symptom is severe abdominal pain, which is either aching, cramping or stabbing in nature. This abdominal pain most often occurs at night and is therefore the most severe. In some patients, abdominal pain is relieved when defecating or passing wind.The stool pattern in IBS is very irregular and can also differ per person per day. Diarrhea and constipation often alternate, even within one day. What is typical is a sudden, unstoppable urge. Other common gastrointestinal complaints are: flatulence, bloating, swallowing problems, heartburn, and the feeling of a lump in the throat. Examples of symptoms outside the digestive system are: muscle pain, fatigue, back pain, headache, irregular menstruation and pain during or after sexual intercourse.


There is no drug treatment for IBS. Advice must be given about lifestyle, anxiety must be removed (stress worsens the complaints), avoidance behavior must be reduced (patients avoid activities because this could make pain worse, worsening the prognosis). Medicines can be given to treat the symptoms (think of anti-diarrheals for diarrhea, laxatives for constipation, or tranquilizers for severe stress), but this does not cure the disease itself.

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