Understanding IBS - Irritable Bowel Syndrome

Irritable bowel syndrome affects 7-15% of the general population (1,2), is twice as frequent in women (3) and is commonly diagnosed in patients below 50 years of age (4). IBS is described as the recurrent episodes of functional gastrointestinal symptoms. The most common symptoms include bloating, abdominal pain, diarrhoea or constipation (5).

Evidence have shown that IBS may be caused by a combination of gastrointestinal motility changes, low-grade inflammation, visceral hypersensitivity, altered microbiota and food components (6-9). However, up to 70% of IBS patients associate symptom aggravation with certain foods (10-13). Therefore, a diet that can trigger or aggravate IBS symptoms are categorised as highly fermentable oligo-,di-, and monosaccharides, as well as polyols (FODMAPs) (14,15).

What is FODMAPs?

FODMAPs stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. They are a group of short-chain carbohydrates (SCCs) that are poorly absorbed in the GI tract and are rapidly fermented by gut bacteria (15-17).

What happens to our body when we consume food HIGH in FODMAPs?

When high FODMAPs enters the body, this evokes a larger production of gas such as hydrogen, methane and carbon dioxide from their fermentation (19), resulting in an increase in small bowel water content (20,21) and causes intestinal luminal distension that in turns provokes bloating, abdominal pain, flatulence and alterations in bowel habits (22).

Every individual reacts to certain groups of FODMAPs differently. A study by Böhn et al. found that 70% of surveyed patients reported to be sensitive to foods high in FODMAPs, 49% reported to be sensitive to diary products [high in lactose], 36% reported sensitivity to beans [galactans] and 23% reported sensitivity to plums [fructose + polyols] (23). While a diet with high FODMAPs triggers various IBS symptoms, it has been reported that a low FODMAPs diet can have a positive impact on IBS symptoms (24-28).

What happens to our body when we consume food LOW in FODMAPs?

Contrary to high FODMAPs, the primary mechanism of low-FODMAPs causes a reduction in small intestinal absorption of osmotically active SCCs. This action results in diminished intestinal water content and downstream effects on colonic fermentation and gas production (29,30).

Here are the list of LOW and HIGH FODMAPs:

You can get the printable PDF list here:


For more information of FOODMAPs, check out https://www.ibsdiets.org/fodmap-diet/fodmap-food-list/

In conclusion...

The purpose of this article is not a total restriction of high FODMAPs in your lifestyle but more of understanding why certain food can make you feel discomfort after eating. Creating the awareness and being able to identify the different food that will trigger or sits well in your stomach helps you to perform better in your day to day activities without disturbances.

I hope the above gives you a clearer picture of why you feel discomfort or experience a change in bowel habits after consumption of certain food in your dietary. However, if you are experiencing severe IBS symptoms, do seek a healthcare professional for help!

With love,



1. American College of Gastroenterology Task Force on Irritable Bowel Syndrome. Brandt L.J., Chey W.D., Foxx-Orenstein A.E., Schiller L.R., Schoenfeld P.S., Spiegel B.M., Talley N.J., Quigley E.M. An evidence-based position statement on the management of irritable bowel syndrome. Am. J. Gastroenterol. 2009;104:S1–S35. doi: 10.1038/ajg.2008.122.

2. Andrews E.B., Eaton S.C., Hollis K.A., Hopkins J.S., Ameen V., Hamm L.R., Cook S.F., Tennis P., Mangel A.W. Prevalence and demographics of irritable bowel syndrome: Results from a large web-based survey. Aliment. Pharmacol. Ther. 2005;22:935–942. doi: 10.1111/j.1365-2036.2005.02671.x.

3. Müller-Lissner S.A., Bollani S., Brummer R.J., Coremans G., Dapoigny M., Marshall J.K., Muris J.W., Oberndorff-Klein W.A., Pace F., Rodrigo L., et al. Epidemiological aspects of irritable bowel syndrome in Europe and North America. Digestion. 2001;64:200–204. doi: 10.1159/000048862.

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5. Horwitz B.J., Fisher R.S. The irritable bowel syndrome. N. Engl. J. Med. 2001;344:1846–1850. doi: 10.1056/NEJM200106143442407.

6. Anastasi J.K., Capili B., Chang M. Managing irritable bowel syndrome. Am. J. Nurs. 2013;113:42–52. doi: 10.1097/01.NAJ.0000431911.65473.35.

7. Mayer E.A. Clinical practice. Irritable bowel syndrome. N. Engl. J. Med. 2008;358:1692–1699. doi: 10.1056/NEJMcp0801447.

8. Mayer E.A., Labus J.S., Tillisch K., Cole S.W., Baldi P. Towards a system view of IBS. Nat. Rev. Gastroenterol. Hepatol. 2015;12:592–605. doi: 10.1038/nrgastro.2015.121.

9. Rajilić-Stojanović M., Jonkers D.M., Salonen A., Hanevik K., Raes J., Jalanka J., de Vos W.M., Manichanh C., Golic N., Enck P., et al. Intestinal microbiota and diet in IBS: Causes, consequences, or epiphenomena? Am. J. Gastroenterol. 2015;110:278–287. doi: 10.1038/ajg.2014.427.

10. Böhn L., Störsrud S., Simrén M. Nutrient intake in patients with irritable bowel syndrome compared with the general population. Neurogastroenterol. Motil. 2013;25:23–30. doi: 10.1111/nmo.12001.

11. Hayes P.A., Fraher M.H., Quigley E.M. Irritable bowel syndrome: The role of food in pathogenesis and management. Gastroenterol. Hepatol. 2014;10:164–174.

12. Eswaran S., Tack J., Chey W.D. Food: The forgotten factor in the irritable bowel syndrome. Gastroenterol. Clin. N. Am. 2011;40:141–162. doi: 10.1016/j.gtc.2010.12.012.

13. Farré R., Tack J. Food and symptom generation in functional gastrointestinal disorders: Physiological aspects. Am. J. Gastroenterol. 2013;108:698–706. doi: 10.1038/ajg.2013.24.

14. Gibson P.R., Varney J., Malakar S., Muir J.G. Food components and irritable bowel syndrome. Gastroenterology. 2015;148:1158–1574. doi: 10.1053/j.gastro.2015.02.005.

15. Barrett J.S., Gearry R.B., Muir J.G., Irving P.M., Rose R., Rosella O., Haines M.L., Shepherd S.J., Gibson P.R. Dietary poorly absorbed, short-chain carbohydrates increase delivery of water and fermentable substrates to the proximal colon. Aliment. Pharmacol. Ther. 2010;31:874–882. doi: 10.1111/j.1365-2036.2010.04237.x.

16. Ong D.K., Mitchell S.B., Barrett J.S., Shepherd S.J., Irving P.M., Biesiekierski J.R., Smith S., Gibson P.R., Muir J.G. Manipulation of dietary short chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome. J. Gastroenterol. Hepatol. 2010;25:1366–1373. doi: 10.1111/j.1440-1746.2010.06370.x.

17. Halmos E.P., Power V.A., Shepherd S.J., Gibson P.R., Muir J.G. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014;146:67–75. doi: 10.1053/j.gastro.2013.09.046.

18. Barrett JS, Gibson PR. Clinical ramifications of malabsorption of fructose and other short-chain carbohydrates. Pract Gastroenterol. 2007;31:51–65.

19. Murray K., Wilkinson-Smith V., Hoad C., Costigan C., Cox E., Lam C., Marciani L., Gowland P., Spiller R.C. Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. Am. J. Gastroenterol. 2014;109:110–119. doi: 10.1038/ajg.2013.386.

20. Barrett J.S., Gearry R.B., Muir J.G., Irving P.M., Rose R., Rosella O., Haines M.L., Shepherd S.J., Gibson P.R. Dietary poorly absorbed, short-chain carbohydrates increase delivery of water and fermentable substrates to the proximal colon. Aliment. Pharmacol. Ther. 2010;31:874–882. doi: 10.1111/j.1365-2036.2010.04237.x.

21. Spiller R.C., Brown M.L., Phillips S.F. Decreased fluid tolerance, accelerated transit, and abnormal motility of the human colon induced by oleic acid. Gastroenterology. 1986;91:100–107. doi: 10.1016/0016-5085(86)90445-2.

22. Shepherd S.J., Lomer M.C., Gibson P.R. Short-chain carbohydrates and functional gastrointestinal disorders. Am. J. Gastroenterol. 2013;108:707–717. doi: 10.1038/ajg.2013.96.

23. *Böhn L, Störsrud S, Törnblom H, Bengtsson U, Simrén M. Self-reported food-related gastrointestinal symptoms of IBS are common and associated with more severe symptoms and reduced quality of life. Am J Gastroenterol. 2013;108:634–41. This study investigates dietary food triggers using a food questionnaire in patients with IBS and their effects on gastrointestinal and psychological symptoms and quality of life.

24. Halmos E.P., Power V.A., Shepherd S.J., Gibson P.R., Muir J.G. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014;146:67–75. doi: 10.1053/j.gastro.2013.09.046

25. Böhn L., Störsrud S., Liljebo T., Collin L., Lindfors P., Törnblom H., Simrén M. Diet low in FODMAPs reduces symptoms of irritable bowel syndrome as well as traditional dietary advice: A randomized controlled trial. Gastroenterology. 2015;149:1399–1407. doi: 10.1053/j.gastro.2015.07.054.

26. Eswaran S.L., Chey W.D., Han-Markey T., Ball S., Jackson K. A Randomized Controlled Trial Comparing the Low FODMAP Diet vs. Modified NICE Guidelines in US Adults with IBS-D. Am J Gastroenterol. 2016;111:1824–1832. doi: 10.1038/ajg.2016.434.

27. Laatikainen R., Koskenpato J., Hongisto S.M., Loponen J., Poussa T., Hillilä M., Korpela R. Randomised clinical trial: Low-FODMAP rye bread vs. regular rye bread to relieve the symptoms of irritable bowel syndrome. Aliment. Pharmacol. Ther. 2016;44:460–470. doi: 10.1111/apt.13726.

28. Gibson P.R. The evidence base for efficacy of the low FODMAP diet in irritable bowel syndrome: Is it ready for prime time as a first-line therapy? J. Gastroenterol. Hepatol. 2017;32:32–35. doi: 10.1111/jgh.13693.

29. Gibson P.R., Shepherd S.J. Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. J. Gastroenterol. Hepatol. 2010;25:252–258. doi: 10.1111/j.1440-1746.2009.06149.x.

30. Valeur J., Røseth A.G., Knudsen T., Malmstrøm G.H., Fiennes J.T., Midtvedt T., Berstad A. Fecal Fermentation in Irritable Bowel Syndrome: Influence of Dietary Restriction of Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. Digestion. 2016;94:50–56. doi: 10.1159/000448280.