What Causes Irritable Bowel Syndrome?

Because the term IBS covers a range of conditions, it follows that there is likely to be more than one cause. The symptoms are thought to be a result of the gut, or a section of it, being overactive or underactive. The gut is a long muscular tube in which food is digested, starting at the mouth and ending at the anus and including the oesophagus, stomach and the small and large bowel - also known as the small and large intestine. Rhythmic muscle contractions in the wall of the gut move food along. If these contractions become stronger or more frequent than usual, pain and diarrhoea may result. If the contractions slow down, or become irregular, there may be constipation.

It is thought that various factors may affect gut activity. Check the list below - could any of these be contributing to your IBS symptoms?

Diet and eating habits
Too much fibre - especially insoluble fibre - can lead to diarrhoea-predominant IBS in some people. Too little fibre can result in constipation-predominant IBS. Intolerances and sensitivities to particular foods and drinks may trigger symptoms, especially spicy foods, fatty foods, wheat, citrus fruits, dairy foods, nuts, coffee, cola and alcohol. Eating too quickly can lead to digestive problems such as wind and bloating.

Stress and anxiety
Stress and anxiety are often implicated in IBS. Research suggests that the brain and gut are closely related via the nervous system. Stress also causes chemical changes in the brain and gut, which are thought to affect how quickly food is pushed through the system. These changes may also alter some people's gut pain threshold. Stress hormones may also irritate the lining of the intestines, leading to leaky gut syndrome', where partially digested food leaks through into the bloodstream, causing an allergic reaction. Eating whilst feeling tense often leads to excess air being swallowed - causing bloating and pain. Some people 'over-breathe' when they're anxious, which allows air to travel down the gullet and into the stomach where it becomes trapped, causing bloating and pain. A rushed, stressful lifestyle often means that people don't take the time to go to the toilet when they need to, which can lead to the bowel becoming lazy' and prone to constipation.

Genetics
IBS often seems to run in families, which has raised the question of whether it is an inherited condition. Research suggests that genetics may play a part, but shared lifestyles are likely to be a bigger factor. For example, children will tend to eat the same foods as other family members, and perhaps learn to react to stress in a similar way.

Female hormones
The female hormones oestrogen and progesterone appear to be implicated in IBS: many women notice a worsening of symptoms, especially cramps and diarrhoea, just before a period, when hormone levels fall.

Gut infections
Around one in six sufferers develop symptoms after suffering from viral or bacterial gastroenteritis. It's thought that infection leaves the gut more sensitive and possibly inflamed, leading to IBS symptoms. The infection itself, or the antibiotics used to treat it, may affect the balance of 'good' and 'bad' bacteria in the gut. Some believe gut infections can damage the lining of the intestines, leading to leaky gut syndrome'.

Bacterial imbalance
Your gut contains a balance of 'good' and 'bad' bacteria that help to break down food. When there are too many 'bad' bacteria, perhaps following an infection or a course of antibiotics, gas and bloating and other IBS symptoms can result.

Yeast infection
Infection with a yeast called Candida albicans has been blamed for IBS symptoms. Candida is present in everyone's gut and is normally kept under control by 'good' bacteria and a healthy immune system. Problems like IBS are thought to occur when there is an overgrowth of Candida, perhaps as a result of a bacterial imbalance following a course of antibiotics, or owing to a compromised immune system following a period of stress or illness. However, many conventional medical practitioners remain sceptical of the role of Candida in IBS.

Medications
Some medications can trigger IBS symptoms. These include antibiotics, non-steroidal anti-inflammatories like ibuprofen and beta-blockers such as Atenolol. Common side effects of ibuprofen include abdominal pain and diarrhoea.

Insufficient sleep
Research suggests that symptoms are made worse by insufficient good quality sleep. This is probably because a lack of sleep increases levels of stress hormones in the body, which in turn affects gut motility.