The cause of IBS is still unknown. 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.
Typically the bowel habit in IBS becomes chaotic. There is no surprised, therefore that it is considered 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, diarrhoea predominant and constipation predominant. In some cases constipation and diarrhoea alternate. Stools in IBS 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 a normal action and the most common is the Gastro colic reflex. This reflex is strongest after breakfast. Gastro-Colic reflex in IBS is strongest after fatty or large meals. This results in abdominal pains and or diarrhoea.
Food is not a cause of IBS but can trigger symptoms.
One suggestion is that it is a brain-gut disorder. The gut has a complex network of brain cells called the Enteric Nervous System. This “Brain of the Gut” is connected to the Brain. To understand IBS, experts think you need to understand how the Enteric Nervous System works.
The highest level of serotonin, a neuro-chemical is found in the gut. At present a lot of research is focused on gut serotonin receptors.
Contractions of the smooth muscles of the gut are affected by serotonin. High serotonin levels are found in diarrhoea and low levels in constipation.
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. Statistics show that there is a greater incidence of psychological trauma and disturbances in IBS. Addressing these issues may produce better long term results.
Gastroenteritis as a cause of IBS: IBS can develop is 20-30% of cases of severe gastro-enteritis. Escherichia coli, Salmonella shigella and Camplobacter jejuni are the most common organisms involved. 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. The passage of food residue along the large gut is affected by the female hormones.
Yeast according to Prof. Jonathan Bostoff of The Meddlesex Hospital could be a possible cause of IBS. An overgrowth of Candida occurs when there is reduced levels of good bacteria, Lactobacilli and Bifidobactreia.