IBS – LOW FODMAP DIET
Irritable bowel syndrome (IBS) is the most common gastrointestinal condition worldwide. It can be a debilitating functional disorder, which includes widely varied symptoms including abdominal pain, bloating, and constipation and/or diarrhoea.
IBS treatment often includes dietary and lifestyle modifications, fibre supplements, probiotics, and medications (antispasmodics, laxatives, antidepressants). While the mainstay of most integrative practitioners has been to remove wheat and dairy from the diet, it has now become increasingly clear that there is no one food or food group proven to trigger IBS symptoms. Dietary interventions that tend to have the most success address functional imbalances, inflammation or both.
LOW FODMAP DIET
The low FODMAP diet was developed by researchers at Monash University in Melbourne, Australia. The premise of the diet is that IBS symptoms are triggered by certain types of carbohydrates called FODMAPs – Fermentable Oligo-(e.g. fructans, galactans), Di-(e.g. lactose), and Mono-saccharides (e.g. glucose, fructose), And Polyols (e.g. sorbitol, mannitol, maltitol, xylitol and isomalt).
Most carbohydrates, once broken down, can be absorbed through pumps on the surface of cells in the gut. However, FODMAPs (rapidly fermentable short chain carbohydrates) can’t be absorbed. The presence of these FODMAPs causes water to be dragged into the small intestine. Additionally, because they aren’t absorbed, FODMAPs travel through the gut to the large intestine. When bacteria in the large intestine get access to FODMAPs they use them for energy to survive. The bacteria rapidly ferment FODMAPs and produce gas as a result. Excess gas production and water retention cause the intestines to expand. When the intestinal wall stretches, the highly connected nerves around the intestines send signals to the brain. People with IBS have very sensitive intestines so these signals contribute to the pain they experience.
Monash University developed the low FODMAP diet to reduce FODMAP intake and to alleviate the distention, bloating and other symptoms associated with IBS.
Process of Elimination
The low FODMAP diet begins with the elimination of all FODMAPs for 6 to 12 weeks. Ideally, IBS symptoms will improve during the restriction period and this improvement will be maintained as FODMAP foods are slowly reintroduced. If symptoms do not improve during the elimination period, it is assumed that FODMAPs are not a contributory factor and the diet is terminated.
The downside to a low FODMAP diet is that many of the foods that are high in FODMAPs are highly nutritious foods which have a beneficial impact on gastrointestinal health including that of proliferating beneficial flora. As such, it is extremely important to try and reintroduce as many of the high FODMAP foods as possible in the long term – specifically foods such as onion, garlic, avocado, broccoli and apple.