What are the causes of Irritable Bowel Syndrome?

No one will give you a specific cause of Irritable Bowel Syndrome. Some experts think IBS is a Motility Disorder.  A hyperactive or oversensitive gut is another possible cause of IBS. and the gut will react to changes influenced by stress, food and hormones.

With the typical chaotic bowel habit of IBS, it is not surprising that it is thought of as a motility disorder. There is an abnormality in the transit time of ingested food.

Sometimes it is slower than normal causing constipation and other times it is faster causing diarrhoea. There are two types of IBS, constipation predominant and diarrhoea predominant. Some have diarrhoea and constipation alternating. In IBS stools can vary from watery and unformed to hard pellets.

Some say there is a link between diet and IBS.
Certain foods will trigger IBS symptoms. Just eating food stimulates intestinal muscle activity. This is the Gastro-Colic reflex and develops in response to food entering the stomach. Gastro-Colic reflex in IBS is strongest after fatty or large meals. This strong gut contraction can cause abdominal pains and or diarrhoea.

There is no evidence that food causes IBS but certain foods and the volume consumed at one time can trigger symptoms.

One suggestion is that the fault that results in IBS resides in the Nervous System. The gut has a complex network of brain cells called the Enteric Nervous System. This “Brain of the Gut” is connected to the Brain. Some researchers believe that to understand IBS, we have to understand the workings of the Enteric Nervous System.

The Gut has the richest supply of serotonin in the body. This chemical is closely connected to the nervous system. At present a lot of research is focused on gut serotonin receptors.

Serotonin affects the nerves in the intestine and controls contractions of the smooth muscles of the gut. Low levels of serotonin lead to constipation and higher than normal levels cause diarrhoea.

Psychological factors such as anxiety, stress and depression can affect the gut. In addition psychological trauma such as physical, emotional and sexual abuse can affect the gut. In IBS, records show a higher incidence of such trauma. It is suggested that in addition to treating the IBS, treating the other issues will give better long-term results.

Gastroenteritis as a cause of IBS: IBS can develop is 20-30% of cases of severe gastro-enteritis. The common infective organisms are Campylobacter jejuni, Salmonella shigella, and Escherichia coli. Serotonin levels in gastro-enteritis is very high and in cases that develop IBS this high level continues.

In women with IBS, the hormones progesterone and estrogen vary during the menstrual cycle and the symptoms may fluctuate. These hormones can affect the colon and the passage of residue along the gut. In some women IBS is worse at certain stage of their cycle.

Yeast according to Prof. Jonathan Bostoff of The Meddlesex Hospital could be a possible cause of IBS. These patients have reduced levels of friendly bacteria, Lactobacilli and Bifidobacteria in their large bowel. This results in overgrowth of Candida.