One in seven Australians has irritable bowel syndrome (IBS). Around one in 10 visits to GPs and half the visits to gastro-enterologists are to do with IBS. Only the common cold accounts for more lost workdays. However, even though it's so common, IBS continues to frustrate those trying to discover its causes and ideal treatment.

The most common symptoms of IBS include abdominal discomfort or pain and bloating, together with constipation, diarrhoea or alternating bouts of both. Twice as many women as men develop IBS, and the most usual age of onset is around 20. It affects people quite differently, with some having attacks that last days, weeks or even months and others dealing with recurrent episodes all their lives.

IBS is described as a functional gastro-intestinal disorder, with no structural or biochemical abnormality being present to explain the symptoms. Physical examination is typically, and frustratingly, normal for people with IBS, enlightening only in its ability to rule out other more serious illnesses such as colon cancer or inflammatory bowel disease. "It appears to be due to increased sensitivity in the bowel, coupled with abnormal bowel contractions, called peristalsis," says Sydney gastroenterologist Dr Katie Ellard.

Only about 20 per cent of people with symptoms of IBS go to the doctor about it. As distressing as it can be, IBS should not be confused with more serious bowel conditions, and does not cause them. However, notice should be taken of a few warning signs.

"Rectal bleeding and weight loss are not symptoms of IBS and should therefore be further investigated," says Professor Terry Bolin of the Gut Foundation at Sydney's Prince of Wales Hospital. Fever and pain during the night should also be looked into, and if you have a family history of either bowel cancer or celiac disease, you shouldn't assume your symptoms are due to IBS.

While it can occur in the elderly, IBS is more common in younger people. "Anyone developing symptoms over the age of 40 should see their doctor, so that other conditions with perhaps more serious consequences, like bowel cancer, can be ruled out," says Professor Bolin. If you're at all worried about your symptoms, that's a good enough reason in itself to go to the doctor.

Before making a diagnosis of IBS, the doctor will probably want to rule out other bowel conditions, including:

• Colon cancer. This is the most common type of internal cancer in Australia. Bowel cancer is uncommon before the age of 40 but its incidence increases after that. Prospects of a cure are much better than most cancers but early diagnosis is vital. One in 18 men and one in 16 women develop bowel cancer.
• Inflammatory bowel disease. This includes Crohn's disease, which may cause inflammation of any part of the gastro-intestinal tract, and ulcerative colitis, which involves inflammation and ulceration of the rectum and colon.
• Coeliac disease. This is caused by an intolerance to gluten, a protein found in various grains. This also causes destruction of the lining of the bowel, and the resultant poor absorption of fats and other nutrients may cause symptoms similar to those of IBS. Coeliac disease can be treated by avoiding all foods containing gluten. It is diagnosed with a small bowel biopsy, although blood tests are helpful.
• Lactose intolerance. The inability to digest the sugar in milk (lactose) can produce similar symptoms to IBS.

It's often difficult to pinpoint a cause of IBS, although it's likely that one or more factors contribute to each individual's condition.

Infection

About a quarter of people with IBS report that their symptoms started after a bowel infection. "It can be any kind of viral or bacterial gastroenteritis," says Professor Bolin. "You don't have to acquire it in Bali, it could be something you pick up in Sydney." Unfortunately, problems can persist for months or years after the infection itself has cleared up.

Antibiotics

A reaction to medications such as antibiotics can be a factor in some cases of IBS. "It functions, we think, in the same way as an infection, damaging the nerves that line the colon, making them more sensitive," says Professor Bolin.

Other causes

"If a patient has not had any recent infection or taken antibiotics, it can be difficult to establish a cause for the symptoms, and that can be frustrating," says Dr Ellard. "You need to take a careful medical history and look at various lifestyle factors and rule out any other possibly important causes of the symptoms."

Diet

Diet is often implicated in IBS, but its exact role is in question. A habit of skipping breakfast is often noted in patients, and symptoms are often worse following a meal. Some experts believe that certain types of food appear to be more troublesome. "Fat, alcohol, coffee and spices will make symptoms worse for some people," says Professor Bolin. Others believe that food itself can be a general trigger, and the type of food doesn't seem to have much of an impact.

A high fibre diet including a wide range of food is what experts recommend to protect against many bowel conditions, although some forms of fibre, particularly those in fruit, can aggravate IBS symptoms in some cases. "However, you should try to have a balanced diet for a few months before deciding it doesn't help," says Dr Ellard.

Stress

Stress is often nominated as a contributing factor to IBS, with more than half the patients identifying a relationship between stress and symptoms. Stress may seem to trigger episodes of IBS, but it's unlikely to be a cause of the condition.

While a number of American studies have suggested that a history of sexual abuse is present in up to 30 percent of IBS, the significance of such findings is not clear. "In the time I've been treating IBS, I've found very little evidence to support such a contention," says Dr Ellard. "However, if patients have had experiences that continue to cause distress, they need to discuss this with their GP."

Hormonal changes in women

No-one knows why more women than men experience IBS. It has often been attributed to hormonal changes, particularly around the time of menstruation, but these assertions are controversial. "Some women with IBS do notice their symptoms get worse either before or during their periods," says Dr Ellard. "But there's no obvious association suggesting hormonal causes of IBS, and clearly, many men get IBS too."

There is no recognised cure for IBS, and treatment is very much an individual thing, based on identifying the probable contributing factors.

A change of diet may help. "You have to sit down and find out what works for each patient," says Dr Ellard. "You can't just tell them to have more fibre, for instance, because that's not necessarily the answer for everyone. Some people get more bloated after eating fibre."

Professor Bolin suggests that those people "might be better off using a bulking agent such as Agiofibe or Metamucil".

To see if IBS is affected by diet or stress, it may be helpful to keep a diary to see if any patterns emerge. If there's a relationship between stress and symptoms, stress management strategies may need to be adopted.

Medication

Anti-spasmodic medications are available to treat the abdominal pain of IBS, but there is little scientific evidence for their effectiveness. However, Dr Ellard believes they have a place as part of an overall strategy. Low-dose anti-depressants may also be used to block the transmission of pain from the gut to the brain. "These are particularly useful for people who have a lot of pain," she says.

"Zelmac (Tegaserod) is a new treatment for people with constipation-predominant IBS. It's not available on the PBS, so unfortunately it is expensive."

Alternative medicine

"Naturopaths are often as good at treating IBS as we are," says Dr Ellard. "We often end up using the same approach."

Says Professor Bolin: "There is also some work that suggests that acupuncture may be of value. A range of alternative therapies haven't been evaluated - the use of slippery elm, peppermint oil or aloe vera, for instance. If you try them and they work, that's fine."

Laxatives

Laxatives may help constipation predominant IBS, but Dr Ellard says that fibre supplements such as Normacol should be tried first. Osmotic laxatives, which draw water into the bowel are preferable to stimulant laxatives such as senna and cascara which can cause problems with bowel function if taken for long periods. Epsom salts are another safe, cheap option.

Finding the best treatment for IBS can be trial and error. "You can usually get a little, and sometimes a lot, better by looking at your diet, exercise and the amount of fluids you drink," says Dr Ellard. "You may need to use various treatments too. The best thing is to keep trying and you can almost certainly get some benefit."

IBS Quick Tips

• Heat may relieve abdominal pain. Try a heating pad, a hot water bottle or a warm bath.
• Eat smaller, more frequent meals, which may be easier to tolerate than larger ones.
• Schedule meals for a time when you can sit down and relax.
• Reduce or eliminate caffeine, alcohol and smoking.
• Wear comfortable, loosefitting clothing.
• Respond to the need to go the bathroom.
• Avoid straining during bowel movements.
• Exercise before eating to stimulate bowel movements.
• Use stress-relieving techniques that work in other areas of your life.
• Drink lots of water.