Low FODMAP Diet: A New Direction for IBS

Debbie Thomas, Prescribing Support Dietitian

Abertawe Bro Morgannwg University Health Board



Irritable bowel syndrome (IBS) has a prevalence in the UK of ~15% and is thought to affect the lives of 1 in 5 people. Symptoms are individual, but are characterised by bloating, abdominal cramps and pain, excessive wind, diarrhoea with ‘urgency’ and constipation.

Traditional dietary management has limited benefits, but the low FODMAP diet is a one-off dietary intervention focusing on the reduction of fermentable carbohydrates and provides better clinical outcomes and improved quality of life.

The low FODMAP Diet:

Fermentable carbohydrates known as FODMAPs (Fermentable Oligo-saccharides, Di-saccharides, Mono-saccharides And Polyols) are fermented by bacteria in the gut resulting in the common symptoms of IBS. Reducing FODMAPs in the diet has been shown to improve gut symptoms in ~75% of people with IBS. FODMAPs are then reintroduced into the diet to identify trigger foods.


185 patients from 5 Bridgend Practices were advised on the low FODMAP diet locally in their GP Practice. Many of the 82 patients who completed their treatment, describe it as ‘life changing’ and some even declare they no longer have IBS. The dietary changes are only temporary and usually only 2 consultations are necessary.

Results of a Symptom Questionnaire completed at each session are shown below:

Graph showing symptom reduction in 82 patients

Additional benefits of the low FODMAP diet Intervention with the low FODMAP diet has also shown benefits with a reduction of 83.6% in IBS-related GP visits as shown in the graph below:

Bar chart showing the number of IBS-related GP visits before and after dietetic intervention (n=95) - an 83.6% reduction

A reduction of 6.25% in prescribing of antispasmodic drugs has also been shown as many patients are able to stop/reduce their IBS medication.


Principle 1: IBS patients being offered the opportunity to work in partnership to improve their condition and quality of life using an evidence-based treatment plan.

Principle 2: Timely referral of those with IBS whose symptoms impact on their life for priority assessment and treatment in their GP Practice.

Principle 3: Ensuring that appropriate tests are undertaken to avoid unnecessary delays in treatment. Offering tailor-made advice and support to ensure that unnecessary dietary restriction can be avoided.

Principle 4: Positive clinical outcomes from this evidence-based approach should enable adoption across the Health Board and ultimately across Wales, providing equity of treatment for IBS patients.

Part of cohort Bevan Exemplar Projects 2016-17