Implementing a Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols Diet in Asia: Addressing Cultural, Clinical and Practical Challenges.

Irritable bowel syndrome (IBS) is a disorder of gut brain interaction characterized by symptoms of abdominal pain, bloating, abdominal distension, and altered bowel habits. 1 Thought to affect 4.1 % of people globally, 2 the symptoms of IBS disrupt daily life, impair quality of life, and are associated with significant mental health comorbidity. 3 , 4 IBS treatments aim to improve symptoms and optimise quality of life, and a holistic approach to care, delivered by a multidisciplinary team of health professionals is widely considered best practice. 5 , 6 This approach incorporates lifestyle modification (commonly diet therapy delivered by a dietitian), medication (delivered by a general practitioner or gastroenterologist), and/or psychological therapy (delivered by a psychologist). Among these approaches, diet therapy has taken centre stage, with particular interest in the fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet. FODMAPs are a group of short chain carbohydrates that are poorly absorbed in the small intestine and rapidly fermented in the large intestine. This fermentation by gut bacteria leads to additional gas accumulation in the gut, distending the intestinal lumen and triggering the classic symptoms of abdominal pain, bloating and altered bowel habits. Multiple trials conducted in at least 14 countries worldwide point to the efficacy of a FODMAP restricted diet to reduce IBS symptoms, certainly in the short term, 7 - 36 with a smaller number of studies identifying long term benefits of up to 18 months. 37 - 40 These data, along with observations of the potential negative implications of the FODMAP diet (eg, for the gut microbiota, nutritional adequacy, and disordered eating risk) 41 have seen the diet evolve into a 3-step strategy. The 3-step approach involves: in (1) Step 1 initially restricting all foods considered high in FODMAPs; then if symptoms improve in (2) Step 2 completing a series of food reintroductions to assess tolerance to individual FODMAPs; and finally in (3) Step 3 developing a personalised diet for long-term, aiming for the minimal level of FODMAP restriction required for reasonable symptom control. 42 Evidence supporting the efficacy of the FODMAP diet therapy for IBS has seen it recommended as a diet therapy in IBS clinical guidelines from India, Japan, Korea, Canada, the United States, and United Kingdom, 43 - 47 though the strength and nature of recommendations vary. For example, the Indian and United States guidelines suggest the diet may be appropriate for selected IBS patients; the United Kingdom guidelines recommend a FODMAP diet it after a trial of ‘traditional dietary advice’; the Canadian IBS guidelines recommend a FODMAP diet after a trial of soluble fiber, peppermint oil and/or antispasmotics; 48 while the Korean guidelines more clearly support its use as a first-line option. It has also seen the diet adapted in the clinic, eg, in the form of the ‘FODMAP Gentle’ approach and the low FODMAP Mediterranean diet and applied to other populations, for instance among individuals with functional gut symptoms associated with inflammatory bowel disease or endometriosis and among older adults with chronic diarrhea. 49 However, the FODMAP diet was primarily developed by Western researchers and tested on participants living in Western countries, using Western foods. Therefore, acceptance and uptake of the FODMAP diet among patients and clinicians in the West has occurred on the back of: Consistent and robust evidence from multiple international studies showing that the diet is effective for IBS symptom management and superior to other diet and non-diet therapies. 50 - 53 Recommendations in multiple clinical guidelines that a FODMAP diet should be used as a first- or second-line therapy for IBS. 43 - 48 , 54 - 56 These recommendations have ensured that the diet is known and accepted among health professionals. Translational research efforts by groups such as Monash University, which has developed an abundance of practical resources for patients and healthcare professionals (eg, the Monash FODMAP diet app, a food certification program, online education courses for patients and health professionals, recipes books, a website, and social media platforms). 57 These resources have driven widespread public and health professional awareness of the FODMAP diet and facilitated the evidence-based implementation of this diet in clinical practice. Dietetic involvement in the delivery of the diet. This approach is supported by evidence, with studies showing the diet is more effective under dietetic guidance. 58 - 60 In practice, dietitians act as the practical enablers of the FODMAP diet, teaching patients how to follow, adapt and individualise the FODMAP diet to suit their personal circumstances. Detailed knowledge of FODMAP composition of a wide range of (mostly Western) foods. These FODMAP composition data have enabled patients, clinicians and researchers to design diets, recipes and meal plans that facilitate implementation of the FODMAP diet in practice and in research settings. 61 - 64 Implementing this same diet among patients following non-Western dietary patterns (eg, in Asia) presents a number of challenges that should be addressed to enable the benefits of this diet therapy to transcend culturally diverse patient groups. The aim of this review is to explore the research, clinical, practical and cultural barriers to implementing a FODMAP diet in patients living in Asia, as well as the potential solutions to overcome these challenges. Studies that have examined the prevalence of IBS in Asian countries have found some variation in prevalence rates, depending on the region studied, the criteria used to classify IBS (Manning, Rome III, or Rome IV), as well as population, age and sex characteristics. For instance, a Rome Foundation global study found that prevalence measured using Rome IV criteria was 2.3% in China, 2.2% in Japan, 1.3% in Singapore and 4.7% in South Korea. 2 A smaller study that used Rome III criteria to classify IBS via internet surveys distributed to 3910 residents in Japan, China, and South Korea revealed the overall prevalence was 12.6%, with considerable regional variation in prevalence rates, ranging from 5.5-15.6%. 65 Similar to observations in the West, in Asia, IBS appears to be more common in younger people, and while the condition predominates females in both regions, the gender gap appears narrower in Asian populations. 66 , 67 With these demographic and regional differences considered, there are four main barriers to the application of the FODMAP diet in Asian countries: (1) research barriers, (2) clinical barriers, (3) practical barriers and (4) cultural barriers. These barriers are detailed below, along with proposed solutions. This narrative review was informed by a broad and iterative search of the peer-reviewed and grey literature using databases such as PubMed and Google Scholar. The reference lists of relevant papers were also reviewed. Literature was included if it addressed the implementation of the FODMAP diet in Asian contexts, with a particular focus on cultural, clinical, practical, or research barriers and enablers. The review aimed to summarise the current evidence and identify opportunities to improve uptake of the FODMAP diet therapy in Asian populations.

Traditional medicine has a long history in Asian culture and encompasses several practices, some of which involve manipulation of the diet ( Table 6 ). Although cross-sectional studies examining the uptake of traditional medicine to treat IBS in Asia suggest that Western medicine predominates treatment, traditional medicine practices remain popular. For instance, a Rome Foundation survey of treatment experience and satisfaction among 1376 patients with functional bowel disorders from 11 cities across Asia reported that 25% had used traditional medicine in the last 3 months, with higher use among patients in China (53%) than other countries where rates were 1 million patients with IBS, with only 6% reporting they used traditional Chinese medicine in the year after diagnosis. Traditional Chinese medicine use was higher among females, younger patients, more affluent patients and patients residing in urban (compared to rural) areas. 97 A common dietary theme among these traditional medicine practices relates to the ‘heating’ and ‘cooling’ properties of foods. 75 , 98 , 99 High FODMAP foods feature in lists of both heating and cooling foods, making dietary principles of the FODMAP diet at odds with those of traditional medicine practices. This adds a layer of complexity for patients and health professionals attempting to combine the 2 approaches. The bridge this gap and build trust with patients, dietitians should learn about the principles of traditional medicine and heating/cooling concepts. This would enable dietitians to guide patients on combining the 2 frameworks or trialling each separately. Educational resources that categorize Asian foods by both their FODMAP content and heating/cooling properties would also be useful to support dietitians in their practice. The FODMAP content of staple foods varies across regions, and has a large bearing on habitual FODMAP intake. This variation affects the ease of implementing a FODMAP diet, with more drastic dietary changes needed if habitual FODMAP intake is high. For instance, if the habitual diet is rich in high FODMAP foods (eg, wheat-based products, legumes, and garlic/onion-heavy cuisine), transitioning to a low FODMAP diet may feel more restrictive and challenging. This was highlighted in a study in India which showed that the FODMAP diet was considered more difficult to implement if wheat was the main staple (eg, among people living in Northern India and in some central areas) and easier where rice was the main staple food (eg, among people in western, southern, eastern and north-eastern areas). 100 Addressing this challenge might require region-specific FODMAP composition information so patients and clinicians can readily identify high FODMAP foods in the diet and culturally appropriate low FODMAP substitutions (eg, for people living in Northern India, low FODMAP substitutes for wheat such as sorghum or millet-based flours and flatbreads). 101 Vegetarian dietary practices also affect the difficulty of implementing a FODMAP diet, and the risk of nutritional inadequacy in people attempting to incorporate the 2 restrictions. Vegetarianism is common in parts of Asia, and a requirement of several dominant religions (eg, Hinduism, Jainism, and Buddhism). For instance, 2011 Indian census data indicated that > 80% of the population was Hindu, Buddhist, or Jain. 102 These religions encourage avoidance of meat for reasons of Ahimsa, or ‘nonviolence,’ thus vegetarianism is considered a compassionate act that is important spiritually. 103 Vegetarianism is particularly common in India, particularly in northern regions, adhered to by 51-90% of the population. 100 Combining the FODMAP and vegetarian dietary restrictions in a manner that is nutritionally adequate is challenging as the requirements are at odds with one another: the vegetarian diet encourages the consumption of non-meat protein sources (eg, dairy products, legumes, lentils, nuts, wholegrains, and soy) whereas a low FODMAP diet restricts these components owing to their high concentration of FODMAPs. For instance, in India, milk, wheat, legumes, and pulses are major vegetarian protein sources, 100 and in East and Southeast Asia, vegetarians tend to replace meat and seafood with soy products, such as tofu, yuba, edamame, nato, soy milk, tempeh, miso, and meat analogues made of soy or gluten (seitan) 104 ––some of which are high or of unknown FODMAP content. Furthermore, foods fortified with nutrients restricted on a vegetarian diet (vitamin B-12, vitamin D, EPA, and DHA) are less widely available in Asia than they are in Western countries such as Australia, North America or Europe. Taken collectively, careful consideration of the potential for nutritional adequacy is needed before a low FODMAP diet is prescribed to Asian patients following a vegetarian diet. Dietitians working with IBS patients who adhere to a vegetarian diet should take a balanced, individualized approach to dietary management, considering the need to both optimize symptom relief and minimize nutritional risks ( Table 7 ).

The low FOMDAP diet has revolutionized IBS management in the west. However, this success has come on the back of extensive research that is generalizable in a western setting; a comprehensive program of food testing to facilitate the design of diets; an assortment of education resources that enable dietitians to teach the diet and patients to implement the diet; and recommendations in multiple international clinical guidelines that foster acceptance and uptake of the diet among health professionals. To facilitate the acceptance and routine application of the FODMAP diet in Asian clinical practice, key practical, cultural, research and clinical barriers must first be addressed. These same lessons may be applicable for the adaptation of other therapeutic diets for gastrointestinal disorders in the Asian setting.