Gut Hypersensitivity and IBS

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Shirley Webber - Research Dietitian, 29 January 2019

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterised by symptoms such as abdominal pain, bloating, distension, constipation, diarrhoea and excessive flatulence. IBS is called a functional gastrointestinal disorder because it is characterised by a cluster of symptoms associated with disturbed gut function despite there being an absence of anatomic or biochemical abnormalities. However, for those of us with IBS we know these symptoms are anything but normal. In fact, they can be very invasive in our daily routines. A diagnosis of IBS should only be made after Coeliac disease, inflammation or any anatomical abnormalities have been excluded. 

The mechanism causing IBS symptoms to occur is not clear but some thoughts are that these symptoms are the result of altered gut microbiota, visceral hypersensitivity, changes in gastrointestinal motility or having low-grade inflammation. The diversity of symptoms coupled with unclear physiological causes of IBS has meant that finding an effective treatment can be a challenge. Despite this, diet has been shown to play an important role in triggering gastrointestinal symptoms for 60% of those with IBS stating that consuming certain foods triggered or exacerbated their symptoms. This observation lead to the research into diet and its relationship with IBS. 

The low FODMAP diet was developed after observing that short-chain carbohydrates from certain foods were poorly absorbed in the small intestine resulting in these carbohydrates being rapidly fermented and through this process increased gas production in the intestine and also draws fluid into the gut. These two reactions to the rapid fermentation of short-chain carbohydrates cause increased pressures in the gut and contribute to distention, bloating and abdominal pain for those with IBS. Two-thirds of people with IBS experience visceral hypersensitivity and therefore any increase of fluid or gas in the intestinal tract triggers the nerves in the gut to send a signal to the brain saying there is pressure in the gut and our body then responds by telling us that we are experiencing gut symptoms or pain. 

To assist with the management of IBS symptoms particularly relating to visceral hypersensitivity following a low FODMAP diet with the guidance of a dietitian for 4-6 weeks can be beneficial to reduce symptoms to a manageable level before reintroducing some FODMAPs back into the diet. Alternatively, psychological therapies such as cognitive behavioural therapy or gut-directed hypnotherapy have been shown to reduce overall symptoms and can be used as standalone therapies or in conjunction with dietary therapies. These therapies look at treating the emotional or psychological aspects that may be triggering symptoms. Where stress or anxiety may be a trigger, exercises such as practicing mindfulness, deep breathing, gentle exercises such as yoga have also shown some benefit on symptoms. 

Each person with IBS responds differently to FODMAPs and different treatment strategies can help each person differently. It’s important to seek help when symptoms are impacting on your quality of life. Keep an open mind and see what therapy may work best for you. Speak to your doctor or dietitian for more information on how to manage your IBS.

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