The FODMAP Diet: What is it & Could it Help Your IBS Symptoms?

The FODMAP Diet: What is it & Could it Help Your IBS Symptoms?

Have you heard of the FODMAP diet? Learn all you need to know about the new nutritional plan that could ease your IBS symptoms

Words Marilena Epitropou, Nutritionist, John Bell & Croyden


The low FODMAP diet has been developed for the management of IBS and other gastrointestinal disorders, such as inflammatory bowel disease. The acronym FODMAP stands for Fermentable Oligo(fructans), Di-(lactose), Mono-saccharides(fructose) And Polyols(maltitol,sorbitol). These are a class of small chain carbohydrates and sugar alcohols (polyols) that are highly fermented but poorly absorbed in the gut.


As this class of carbohydrates and polyols are not absorbed in the small intestine. They transit quickly in the large intestine where they quickly get fermented by colonic bacteria, resulting in gas production. As they are highly osmotic, FODMAPs attract water in the large bowel. The combination of gas and water cause distension in the intestinal lumen, resulting in pain, bloating and affecting bowel motility.

To follow a low FODMAP diet, is to avoid foods high on these fermentable, poor-absorbed carbohydrates such as wheat products, some fruits and vegetables and dairy products.


The low FODMAP diet is a 3-phase intervention. The first phase requires strict elimination of FODMAP foods for 4 up to 8 weeks. During this time the individual should identify whether symptoms improve on the diet. If there has been improvement high FODMAP foods are reintroduced in the diet one at a time during the second phase, to identify which foods the individual is more sensitive to.

Finally in the long term, the diet resumes to normal, personalised to exclude only those foods that trigger symptoms. The diet should be followed under the supervision of a dietitian. An experienced dietician will provide the patient with education material and support and will design the diet in a way that is nutritionally complete.


The low FODMAP diet excludes many staple foods such as legumes, dairy products, some cereals, fruits and vegetables. As with any restrictive diet, it carries the risk of nutrient inadequacy. A factor also to be considered regarding the diet is the possible alteration of the gut microbiota. Fructans and galacto-oligosaccharides which are included in the FODMAPs have prebiotic actions. Their drastic elimination from the diet may lead to reduced numbers of beneficial bacteria, specifically Bifidobacteria, changing the colonic environment.


Adherence to a low FODMAP diet has been shown to have a positive effect on IBS symptoms especially bloating and diarrhoea. However, more research still needs to be done to determine its long term effects on the colonic environment. It should be applied to appropriate situations and always with the supervision of an experienced dietitian to ensure nutritional needs are met.

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