About 20% people in Singapore and 11% people globally experience the irritable bowel syndrome (IBS) [1, 2] Signs and symptoms of IBS include cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both [3].

Although the exact mechanism is unclear, a diet low in fermentable carbs, called low FODMAP diet, is often recommended to manage the IBS [4].

What Is FODMAP?

FODMAP stands for Fermentable Oligo-, Di-, and Monosaccharides, And Polyols. It is a class of small, nondigestible carbohydrates which are poorly absorbed in the small bowel but easy to be used by the intestinal microbiota, producing gas from the fermentation reaction. The osmotic activity of the FODMAP food drives water into the gastrointestinal tract. These actions can cause symptoms such as bloating, abdominal pain, diarrhea, etc. [4]

 A person’s symptom may be triggered by one or several of the FODMAP foods but not all FODMAP foods will cause abdominal symptoms in the same person [4].

The List of FODMAP Foods

Below is a non-exhaustive list of FODMAP foods in each category [5, 6]:

Oligosaccharides:

Fructans: found in wheat, rye, inulin (a fiber additive in many foods), onions, garlic, artichokes.

Galactans: found in nuts and legumes such as beans, chickpeas, lentils and soy-based products, as well as in broccoli and Brussels sprouts.

Disaccharides:

Lactose-containing products: dairy milk, yogurt, soft cheese, ice cream, buttermilk, condensed milk, whipped cream

Monosaccharides:

Fructose-containing foods: fruits such as apples, pears, watermelon, mango, peach, cherries, sugar snap peas

Sweeteners: honey, agave nectar, high fructose corn syrup

Polyols: 

Sugar alcohols (mannitol and sorbitol): found in blackberries, watermelon, apples, apricots, cherries, nectarines, peaches, pears, plums, and other stone fruits. Vegetables: mushrooms, cauliflower, snow peas.

Sugar alcohols (sorbitol, mannitol, xylitol, maltitol and isomalt): used in sugar-free and low calorie sweeteners in foods such as candy and gum; also in some cough medicines and cough drops.

How To Manage a Low FODMAP Diet

A low FODMAP diet is not meant to exclude all FODMAP food, but to minimize the consumption of the trigger foods. Here’s how you can do it [6]:

Step 1. Identify the trigger foods

An initial restriction phase of 4 weeks is recommended. During this phase, intake of high-FODMAP foods should be minimized.

After that, slowly reintroduce FODMAP foods from one category at a time to find out which food causes symptom.

Step 2. Personalize your diet

The FODMAP foods that do not cause symptoms can be safely consumed. Those that cause symptoms can further be adjusted on their intake level, because a smaller amount might be tolerable. The ultimate purpose is to keep as many food options in your “allowed” list as tolerated.

IBS is a chronic condition that you’ll need to manage long term. Do take note that for people without IBS, it is not necessary to follow a low FODMAP diet.

References

[1] Siah, K.T.H., Wong, R.K., Chan, Y.H., Ho, K.Y., and Gwee, K.-A. (2016). Prevalence of Irritable Bowel Syndrome in Singapore and Its Association with Dietary, Lifestyle, and Environmental Factors. J Neurogastroenterol Motil 22, 670–676.

[2] Chatila, R., Merhi, M., Hariri, E., Sabbah, N., and Deeb, M.E. (2017). Irritable bowel syndrome: prevalence, risk factors in an adult Lebanese population. BMC Gastroenterol 17, 137

[3] Mayo Clinic. Irritable Bowel Syndrome.

[4] Bellini, M., Tonarelli, S., Nagy, A., Pancetti, A., Costa, F., Ricchiuti, A., de Bortoli, N., Mosca, M., Marchi, S., and Rossi, A. (2020). Low FODMAP Diet: Evidence, Doubts, and Hopes. Nutrients 12, 148.

[5]  Lang, A, and Rossi, M. (2022). A Beginner’s Guide to the Low FODMAP Diet. Healthline.

[6] Padgett, C. (2019). FODMAP Gut Check: Test Your Knowledge. IDEAFIT.