IBS and the Low FODMAP Diet

The Low FODMAP Approach 

Modifying FODMAPs can be an effective for irritable bowel syndrome (IBS). This approach can help give 3 out of 4 people improved control over troublesome symptoms.

Research has shown that a group of dietary sugars, FODMAPs, can be poorly absorbed in the small intestine and fermented by our gut bacteria to produce gas, and cause more water to be delivered through the bowel. This can trigger symptoms such as bloating, pain, diarrhoea, nausea and in some cases constipation.

FODMAPs can be poorly absorbed in the small intestine and are then fermented by our gut bacteria in the large intestine to produce gas, and cause more water to pass through the bowel. This happens in all of us, some gas means our gut microbes are being fed. However in people with IBS this can trigger symptoms such as bloating, pain, and diarrhoea.

Watch a short helpful video from the Monash University FODMAP team here .

It is important to note that FODMAPs are not the underlying cause of IBS. In IBS nerves around the gut are hyper-sensitive, so normal digestion can feel painful, urgent, or uncomfortable. The gut-brain connection can also become overreactive and amplify discomfort and pain.

FODMAPs is an acronym for the group of sugars that are poorly absorbed by our digestive tracts:

Fermentable

Oligo-saccharides

Di-saccharides

Mono-saccharides

And 

Polyols

The first phase is the low FODMAP 'test' diet which restricts these sugars for 2-6 weeks. If symptoms improve the second phase is to re-challenge with some of the high FODMAP food groups. Once you have identified your major triggers, the third phase is to move to a least restrictive personalised version of the diet which allows symptom control. It is essential not get stuck in the low FODMAP phase for too long as the diet can be restrictive and lower levels of some of the beneficial gut bacteria.

As the FODMAP diet can seem complex and confusing, advice is best provided by a dietitian who has received  training and is experienced in this area. They can help you to individualise the process and also ensure that your diet is nutritionally balanced. Bridget has completed recognised training run by Monash University and King's College London.  

References

O'Brien, L., Kasti, A., Halmos, E.P., Tuck, C. and Varney, J. (2024), Evolution, adaptation, and new applications of the FODMAP diet. JGH Open. 2024; 8(5): e13066. 

Lomer MCE. The low FODMAP diet in clinical practice: where are we and what are the long-term considerations? Proceedings of the Nutrition Society. 2024;83(1):17-27.

Whelan K, Staudacher H. Low FODMAP diet in irritable bowel syndrome: a review of recent clinical trials and meta-analyses. Curr Opin Clin Nutr Metab Care. 2022; 25(5): 341-7.