IBS is very common and, according to the IBS Network charity, it affects 10 to 20 per cent of the UK population at any one time.
Scientists haven’t found one cause of IBS, and current thinking is that, like many diseases, it is caused by a combination of genetic and environmental triggers.
Although no specific genes have been identified to date, there are lots of theories as to what the triggers for IBS are. It’s more common in people who suffer from stress, anxiety and depression, for instance.
It has also been found to develop after a bout of gastroenteritis (inflammation of the intestine). A Canadian study found that up to a third of people who suffered from a local outbreak of waterborne dysentery went onto to develop IBS symptoms.
The gut microbiome – the bacteria that live in the gut - may also be involved in IBS.
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) – short-chain carbohydrates found in a wide range of foods and drinks – are another possible cause for IBS. The theory is that they are poorly absorbed in the intestine, and can enter the colon where they are fermented by bacteria, causing bloating, a swollen tummy, and diarrhoea. Though most people can digest FODMAPs, it is argued that some may have sensitive guts, and are therefore not to be able to digest them - thereby developing IBS.
There's currently no test to identify IBS – when the gut is examined it will look normal and there are no chemicals or inflammatory markers that show up in blood tests.
The National Institute of Health and Care Excellence (NICE) guidelines say GPs should consider an IBS diagnosis if you've had abdominal pain or discomfort, bloating and a change in bowel habit for at least six months. GPs are asked to look out for 'red flag' symptoms for more serious conditions, such as unintentional weight loss, rectal bleeding, a family history of bowel cancer or anaemia, and a change in bowel habit to looser, more frequent stools in those aged 60 and over.
Tests you may have include a full blood count, a test for inflammatory markers in the blood and antibody testing for celiac disease.
Who gets IBS?
You're more likely to get IBS if you're a woman, and aged under 50 (it normally starts before you reach 35). It also tends to run in families, but no IBS gene has been identified.
There's no one cure for IBS but there are several effective treatments to control individual symptoms. It's often a question of experimenting with your diet and trying different medication.
Dietary changes may make a difference to constipation, including a diet rich in soluble fibre (e.g. fruit and vegetables). However, if you have a condition called ‘slow transit constipation’, where the gut doesn't move food quickly enough, fibre can make your symptoms worse.
NICE recommends having no more than three portions of fresh fruit a day, limiting tea and coffee to no more than three cups a day and restricting high fibre foods such as bran and wholegrains.
As mentioned above, a diet high in FODMAPs – found in onions, wheat, rye, bread, garlic, artichokes, legumes, milk, honey, apples, pears, watermelon, mango, mushrooms and cauliflower – can cause bloating, pain and diarrhoea. Studies have shown following a low FODMAP diet can improve IBS symptoms in 74 per cent of cases.
Medication to help ease symptoms include: peppermint oil and mebeverine for relaxing muscles in the gut, relieving pain and cramps, while laxatives such as Fybogel (ispaghula husk) can ease constipation. Anti-motility drugs (including loperamide) can control diarrhoea. The antidepressant amtriptyline can help with IBS pain.
Probiotic supplements, which help balance gut microbiome by repopulating your gut’s levels of 'friendly' bacteria, may also be helpful and there has been some promising research findings.
Psychological therapies, including gut-directed hypnotherapy, cognitive behavioural therapy (CBT), mindfulness and psychotherapy may also be worth trying if your symptoms don't respond to other treatments after 12 months.