8 things to know about a low FODMAP Diet


A low FODMAP diet is effective for managing functional gastrointestinal symptoms, particularly irritable bowel syndrome (IBS), so it is of value to patients and GPs.

Now 12 years old, the diet is being used across the world as a first line dietary therapy for both adults and children.

Significant reduction of symptoms are seen in more than half (usually ~70%) of patients with IBS, in both clinical trials and real-world experience.

A 4 week trial is recommended to assess whether the diet is useful in controlling bloating and other intestinal complaints of IBS.


1. What are the key principles?

The key principle of the diet is that foods high in specific fermenting short-chain carbohydrates (FODMAPs), that are either:

  1. Indigestible (Lactose, Fructans, Galactans) or
  2. Slowly absorbed from the small intestine (Fructose, Sorbitol, Mannitol)

are avoided and replaced by foods low in FODMAPs.

FODMAPs can lead to an increase in small intestinal water content, and are readily fermented by gut bacteria-yielding gases (hydrogen, carbon dioxide and methane), the overall outcome being increased distension of the small intestine often producing abdominal bloating.

2. How is the diet practised?

The diet is practised in two steps:

  1. An exclusion phase — during which strict adherence to the diet is important in order to determine whether the individual will respond to the diet (expectation is 70%); and
  2. A reintroduction phase — during which foods are re-introduced to determine the level of restriction needed to maintain satisfactory symptom level (75% of responders will be able to reduce restriction considerably).

If there is good adherence to the diet but inadequate response to the exclusion phase, then it should be stopped. Patients are sometimes reluctant to stop despite lack of efficacy.

3. What the diet is

The low FODMAP diet is a therapeutic approach to relieve gastrointestinal symptoms. It is particularly effective for abdominal bloating and distension, but also helps pain, altered bowel habits and fatigue associated with those symptoms.

4. The diet is not…

  • A diet for good health (FODMAPs have prebiotic properties).
  • Recommended to be followed if it is ineffective.
  • Something to continue strictly for life — reintroduction of FODMAPs to tolerance is important and successful in the majority of patients.
  • A ‘cure’ for IBS, but rather minimises those symptoms by reducing bloating and other GI complaints.
  • A diagnostic test for IBS. Whether there is a response or otherwise, the diet cannot be used to decide whether further investigations are needed.

5. Who should be treated?

The diet is suitable for any patient with troublesome gastrointestinal symptoms that do not settle following the establishment of a firm diagnosis and simple reassurance.

For those keen to use dietary strategies, it is suitable as a first-line therapy.

6. Who should not be treated?

Those with or at high risk of eating disorders should be discouraged from using a restrictive diet as therapy.

7. Who should initiate/teach the diet?

The low FODMAP diet has been developed and tested to be dietitian-delivered. The dietitian teaches the reasons for the diet, foods to avoid and appropriate alternatives to ensure nutritional adequacy, and, in the follow-up appointment, instructs on reintroduction strategies. They usually provide written information and direct the patient towards digital information, especially the Monash University Low FODMAP Diet app that provides accurate and up-to-date information on food content and other aspects of the diet.

8. How can you use the diet ?

  • Following a diagnosis of IBS, a Low FODMAP diet is a crucial 1st step.
  • Referral to a dietitian trained in the low FODMAP diet is recommended to assist with tailoring the diet and re-introduction of FODMAPs.

Useful links

Download a Low FODMAP Diet – click here for PDF

Low FODMAP App smart phones http://www.med.monash.edu/cecs/gastro/fodmap/

Patient Support Website  http://www.ibsgroup.org/

Reference: http://www.medicalobserver.com.au/medical-news/gastroenterology/pioneers-of-the-low-fodmap-diet-answer-8-key-gp-questions