The Pulse Irritable bowel syndrome: is diet the key?
by Pamela Wilson
There's no cure for irritable bowel syndrome, but knowing which foods your gut is sensitive to can help you take control of the symptoms and reduce their impact on your life.
A staggering 10% to 20% of the population suffer from symptoms consistent with irritable bowel syndrome (IBS).
This means there are at least 2.2 million Australians struggling with its effects: bloating; distension; abdominal pain; constipation; diarrhoea; excessive wind; a noisy abdomen; nausea; fatigue.While it is thought that stomach viruses, stress and an abnormal balance of bowel bacteria are possible triggers of IBS, it is believed the major underlying trigger is a food intolerance. While drug therapy for IBS is largely unsuccessful, a dietary management plan that is low in certain naturally occurring sugars known as FODMAPs, is proving itself to be an effective treatment for many IBS sufferers.
It doesn't work for everyone, but research has found three out of four people trialling the diet, developed in Australia by nutritionist Dr Sue Shepherd and gastroenterologist Professor Peter Gibson, reported a marked improvement in all their symptoms. And earlier this month, UK researchers reported patients following a low FODMAP diet appeared to have better control of their IBS symptoms than patients who stuck to the standard dietary advice.
Overview of the low FODMAP diet
FODMAPs is the user-friendly acronym for 'Fermentable Oligosaccharides, Disaccharides, and Monosaccharides and Polyols', which are all indigestible sugars that occur naturally in foods. These dietary sugars are not absorbed well by the body and they increase the water content in the gut and produce excess gas, causing the symptoms of IBS.
The reason some people experience painful and uncomfortable symptoms while others don't is because of their gut sensitivity, explains Gibson, professor of gastroenterology at Monash University and The Alfred hospital in Melbourne. "In people with irritable bowel they have hypersensitivity in the gut ... where even normal physiological distension will be felt and they might get changes in their bowel habits, bloating or pain," he explains.
The diet is also believed to be helpful for some symptoms in people with inflammatory bowel disease, such as Crohn's disease and ulcerative colitis. Although it doesn't treat the underlying disease or inflammation, it can relieve symptoms resulting from a sensitivity triggered by the medical condition, explains Professor Michael Grimm, president of the Gastroenterological Society of Australia. "When those patients get effective treatment and the disease goes into remission, a lot of them are left with residual symptoms that are related to the bowel being hypersensitive ... (but) it's no longer inflammation, it's an irritability," he says.
The philosophy of the diet is simple. It is recommended you strictly avoid all FODMAPs for at least two months. Once your symptoms have improved, you can gradually reintroduce one FODMAP group at a time to see how much, if any, you can tolerate.
Is the low FODMAP diet for you?
If you suffer from any of the symptoms commonly associated with IBS, it is very important you firstly visit a GP to be assessed for medical conditions such as coeliac disease, ovarian cancer and inflammatory bowel disease. Once these have been ruled out, your next best step is to find a dietitian trained in managing the low FODMAP diet. While there are books available to guide people, the diet can be complex and strict at first so it is best done with the help of a professional.
There are also a number of other factors you should consider before starting the diet. Firstly, the research found that four out of five people felt the diet was easy to maintain, but Grimm points out that because it requires fundamental dietary change it can put a big imposition on sufferers and their families. Therefore, individuals need to decide if it is the right treatment for them.
"It's onerous, it requires a big commitment, you need to search out the foods that fit with the diet so if you live in a family either you cook for yourself or everyone ends up on the low FODMAP diet with you," he says. "I think most people would reserve it for the most severely affected patients."Nutrition Australia Senior Nutritionist Aloysa Hourigan treats some of her IBS patients with the diet and says it has reduced the symptoms and improved quality of life for many of them.
"One of my patients was going camping with friends and she was dreading it because her wind was so bad. Within a few weeks of following (the low FODMAP diet) she is now able to function better socially. It minimises symptoms to a level where they are much more controllable," she says. "It makes good clinical sense. It makes good scientific sense. It is definitely not a fad diet, it is there to treat symptoms."
Despite the relative success of the diet, Gibson and his team are not resting on their laurels. They are conducting ongoing research to look at various safety elements. Because the diet does restrict many foods, the researchers are looking further into it to ensure it is nutritionally adequate.
We believe it is because there are so many alternative safe foods which can replace the others," Gibson adds. Secondly, there is a theory that the low FODMAP diet may result in fewer prebiotics, which are short-chain carbohydrates, being in the gut. These are believed to stimulate the good bacteria in the bowel and suppress the bad.
"They are supposed to be good for calcium absorption, and for preventing bowel cancer," explains Gibson. "We are trying to determine whether we are changing the conditions in the large bowel which might be less favourable for bowel cancer and things like that. So far, we have seen no evidence for this" Grimm says while this is an important point to consider, for those people with serious IBS symptoms they need to weigh up possible risks with the chance that they could improve their quality of life.
"If people are severely disabled and are missing a lot of work or whatever ... I think that the theoretical risk is outweighed by the inconvenience and suffering and the potential to improve on that," says Grimm. Meanwhile, it is very important for everyone on the diet to ensure they are seeking replacement foods for those being taken out. Wheat is restricted on the diet, so it is vital you find substitutes because cereals and grains provide fibre, vitamins and are an important source of energy. Hourigan says this also applies to those people who find they can only drink lactose-free milk. "They shouldn't just say they won't drink milk anymore, they should find an alternative," she says.