Efficacy of The Low FODMAP Diet in Malaysian IBS Patients

Irritable bowel syndrome (IBS) is diagnosed based on the Rome IV criteria with recurrent abdominal pain, on average a minimum of 1 day/week, related to 2 or more of the subsequent criteria; associated with defecation, modifications in frequency and appearance of stool. These factors ought to be fulfilled for an on-going 3 months with an indication onset of a minimum of 6 months before the diagnosis. IBS is additionally sub-typed into IBS with constipation (IBS-C), IBS with diarrhoea (IBS-D), mixed IBS (IBS-M), and unspecified IBS (IBS-U) 1. Symptoms vary among individuals due to its complex and unclear pathophysiology, making IBS a heterogenous disorder. The most common underlying issue is presence of nutrients within the alimentary tract affecting gastrointestinal motility, sensitivity, barrier performance, and gut microbiota. Likewise, food hypersensitivity and food intolerance are also found to underlie the pathologic process of IBS. Hypersensitivity to known foods might play a role by inflicting inferior internal organ inflammation, enhanced cells permeability and visceral hypersensitivity. Bioactive synthetics in food sources, likewise, may contribute to- and trigger gastrointestinal (GI) indications in IBS. Luminal distension is another pathologic condition in that short-chain carbohydrates in foods can trigger luminal water retention and gas creation, leading to bloating and hypersensitivity 2. However, patients with IBS have been reported to have provoking symptoms after ingestion of certain dietary meal  3

Therapeutic approaches to alleviate IBS symptoms are by pharmaceutical and non-pharmaceutical treatments. Unfortunately, pharmaceutical treatments alone do not seem to be invariably enough to supply adequate symptom relief. In such cases, dietary intervention was required to attenuate symptoms. FODMAPs, which stands for fermentable oligo-, di-, and mono-saccharides and polyols was used to describe the poorly absorbed, short-chain carbohydrates which are in large part indigestible withinside the small gut due to absence of sufficient hydrolase enzymes or incomplete absorption 4. FODMAPs are fermentable carbohydrates that are commonly present in food sources such as onion, garlic, pulses, legumes, wheat, vegetables, fruits, dairy and dairy products (Figure 1). Accumulation of FODMAPs triggers gastrointestinal symptoms in IBS patients by increasing small intestinal water causing osmotic effect. It is also fermented by colonic microbiota resulting in gas production leading to colonic distension and abdominal pain in patients  5-7. Therefore, a diet low inFODMAPs has been recommended as a diet therapy for IBS patients.

Almost 50-80% of IBS patients who suffer from pain, bloating and, diarrhoea demonstrate improved gastrointestinal symptoms after being on a low FODMAP diet  8.  The low FODMAP diet involves 3 phases with the first being restriction of FODMAPs for 4-8 weeks for the determination of food-specific related symptoms. Once noting symptom improvement, FODMAPs are then reintroduced lasting between 6-10 weeks in order to distinguish its tolerance among the various carbohydrates. Foods avoided will be rechallenged in small amounts to determine tolerance based on type and amount of FODMAPs followed subsequently by a diet personalization phase  8,9. This diet should be administered by dietitians with a special interest in IBS due to the restrictions involved  9,10. However, the low FODMAP diet is not regarded as a first line therapy as patients with constipation show little improvement and those with dietary restrictions, nutritionally compromised or even children find the restrictions challenging leading to poor adherence to the diet. It is also less practical for those who regularly eat out and the low palatability of certain food products  11.

As a result, the first line therapy recommended to newly diagnosed patient is to follow a healthy, balanced diet with regular meal pattern, to avoid skipping meals, leaving long gaps between meals, and to incorporate lifestyle changes. Although a diet high in fibre, adequate fluid, limiting alcohol and caffeine intakes, and low in fat and spices consumption have also been suggested, there is very weak evidence for this recommendation  12. In any case, patients with persisting symptoms are then advised to go on the low FODMAP diet. Recently a bottom-to-top approach has also been suggested whereby patients only need to restrict certain groups of FODMAPs and can still consume fruit sugars (mono-saccharide) and milk sugars (di-saccharide). However, the efficacy of this approach could only be determined through randomised controlled trials  8.  

 In the Malaysian general population, IBS prevalence rate was reported at 14% compared to 15.8% among young adults in Malaysia 13. Among Asian populations, the prevalence of IBS ranged from 3.2% to 22.8%. In Thailand, Singapore, and Hong Kong, the prevalence of IBS among the general population was reported as 4.4%, 2.3%, and 6.6% respectively 14. However, the prevalence in Europe and North America was between 10-15%. Malaysia has been reporting higher prevalence rate than several Asian countries but remains lower than the rest of the world. The different nutritional content and socioeconomic situation in Malaysia as compared to western countries, in addition to the rest of Asian countries underlies the possible cause of the differences 15. A large amount of FODMAPs in the Malaysian diet usually comes from onion, garlic, shallots, legumes and wheat  16. Rice, being a staple food in Malaysian diet, is classified in the low FODMAPs category but the accompaniment of popular dishes such as curries consisting of legumes/pulses are typically high in FODMAPs  17. On top of that, our dietary pattern is also changing, and large numbers of Malaysians dine out and opt for international cuisines which suggests that our FODMAP intake could also be as high as our western counterparts. Therewithal, most Malaysians usually eat to their satiation as many are also not used to the idea of measuring and eating in reasonably healthy portions and may find this task tedious. Besides, poor information of FODMAPs content on native diet, poor labelling of packaged food ingredients, poor social acceptance of low FODMAPs foods, lack of social awareness in the society, and lack of information of the dietary literature 16 result in difficulties formulating dietary recommendation based on the low FODMAP content of foods with supported portion size  12. Therefore, until there is enough data to develop a suitable intervention for our population, the first line of therapy will continue to be the recommended strategy for all new patients and only those with severe persisting symptoms will be advised to go on a low FODMAPs diet.


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