Functional gastrointestinal disorders (FGIDs) are disorders with chronic or recurrent symptoms attributable to the gastrointestinal (GI) tract in the absence of organic disease that can be identified by routine investigations. Diagnosis of FGIDs are mainly based on patient’s symptoms interpretation and reporting. Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are among the most established FGIDs. They are also one of the most common gastroenterology conditions encountered in the community, as well as in gastroenterology and specialist clinics. Yet these conditions are not well understood and constantly pose treatment difficulties to clinicians. Although FGIDs do not lead to an increase in mortality,^1,2 they cause significant morbidity, in terms of affecting quality of life and increasing healthcare utilization.^3–5

FGIDs are known to result from a complex interaction between biological, psychological and social factors.⁶ In the biopsychosocial model of IBS, developed by a multi-disciplinary expert committee in an attempt to understand the condition better, genetic and environmental factors influence both the brain and the gut, which in turn interact bidirectionally via the autonomic nervous system and the hypothalamus-pituitary-adrenal axis. Within this model, culture forms an integral component of the environmental factors.⁶ Culture is defined as the values, beliefs, norms, and practices of a group of people which guide thinking, decisions, and actions in a patterned way.⁷

In 2 recent review articles on FD⁴ and IBS,⁸ various differences in clinical presentation and impact of these conditions were observed between the East and the West. In these reviews, “East” included countries from Asia, while Western countries included countries from Europe, North America, and Australia, mainly due to similarities in culture and diet.⁹ Whilst some of these clinical variations may have been due to epidemiological differences between Asian and Western populations, it is likely that differences in culture may have had a role as well. The influence of culture on various aspects of the diagnosis, treatment and health outcomes of FGIDs in Western studies have recently been reported.⁷ However, little is known about the impact of culture on FGIDs in the East/Asia. This review attempts to highlight the role of culture in FGIDs in the East with regards to: symptom presentation and diagnostic issues, lifestyle and cultural habits, epidemiology, and healthcare seeking behavior.

FD based on the the Rome III and IV criteria is subdivided into epigastric pain syndrome (EPS) and post prandial distress syndrome (PDS).¹⁰ PDS involves patients with early satiety, and post-prandial fullness and is considered to be meal related. EPS includes patient presenting with epigastric pain or burning and is considered to be non-meal related. A recent review article has indicated that the proportion of patients with PDS and EPS appears to differ between the East (Asia) and the West.⁴ Studies in Korea and Japan using the Rome III criteria reported that PDS was present in 69.9% and 81.3% of patients with dyspepsia, whereas studies in the United States reported that only 50.0% of their patients with dyspepsia presented with bloating.¹¹ Recently, two large endoscopy-based community studies in Taiwan and Canada, using similar diagnostic criteria for FD, were published. In the Taiwanese study, 71.9% of 491 patients with FD had a PDS sub-type and 34.4% had an overlap of EPS and PDS,¹² while 347 (40.8%) had PDS alone, and 351 (41.2%) met the criteria for both EPS and PDS in the Canadian study.¹³ In a cross sectional study comparing Malaysian and British age-matched adults who were referred for endoscopy, investigators reported that Malaysian patients with dyspepsia had a significantly higher frequency of belching (70.0% Malaysian vs 30.0% British, P < 0.001) and early satiety/bloating (52.0% Malaysian vs 32.0% British, P < 0.001) compared with their British counterparts.¹⁴

Among the various possibilities as to why PDS or dysmotility-type FD is more common in Asians compared to Westerners, lies the role of Helicobacter pylori infection. H. pylori associated chronic gastritis is thought to cause FD symptoms by altering gastroduodenal motility and sensitivity, including influencing the production of GI hormones and neurotransmitters somatostatin, gastrin, and ghrelin. Furthermore, H. pylori is postulated to damage the ghrelin producing gastric X/A like cells. As a result, ghrelin secretion decreases which could delay gastric emptying, resulting in postprandial fullness.¹⁵ The fact that the prevalence of H. pylori is higher in Asia and that infected Asian adults with FD tend to have a greater symptom response with eradication therapy compared to Westerners¹⁵ supports its role for the difference in FD sub-types between the East and West (Table 1).

A major factor for the difference in H. pylori prevalence between the East and the West has been attributed to variations in sanitation and socioeconomic status.¹⁶ However, certain cultural practices have been suggested as contributing towards a greater prevalence of H. pylori in East Asia. A study of Asian immigrants to Australia had previously identified that the use of chopsticks was an independent predictor of H. pylori presence.¹⁷ This study additionally demonstrated a difference in H. pylori prevalence between ethnic Chinese migrants from Malaysia/Singapore vs those from mainland China, supporting the notion that different cultural practices influenced the transmission of H. pylori.

Globally, the diagnosis of IBS has been based on the “Rome Criteria” which includes recurrent abdominal pain (Rome IV) or discomfort (Rome I–III), related to defecation, associated with a change in frequency or consistency of stool.¹⁰ However, the recent Asian consensus on IBS reported that “abdominal pain” was not commonly identified in Asians with IBS, while bloating and discomfort were more common and even defined bloating as a key symptom in IBS patients in Asia.^18,19 This cultural variation in symptom perception was elegantly demonstrated in a multi-center, Indian study using different diagnostic criteria for IBS (MIIBS). Ghoshal et al²⁰ reported that the Manning criteria had the highest sensitivity (91.0%), followed by the Asian criteria (74.5%), whilst the Rome I (68.0%), Rome III (52.5%) and Rome II (40.0%) had much lower accuracies. In both the Manning and Asian criteria, “abdominal pain or discomfort” were not included as an absolute requirement for the diagnosis of IBS, which resulted in their greater frequency for diagnosing IBS in the Indian population.⁸ Similar findings have been reported in other Asian populations. In a Hong Kong study, 68.0% of patients with IBS reported bloating, compared to only 32.0% who complained of abdominal pain.²¹ In a study from Singapore, 62.0% of IBS patients complained of abdominal bloating.²² In a study of 662 subjects from China, 58.0% of patients reported abdominal pain compared with 63.0% with bloating (Table 2).²³ If the Rome IV criteria is followed, whereby abdominal pain is mandatory, then more Asian patients with IBS will be under-diagnosed.²⁴Table 3 highlights the different symptom-based diagnostic criteria for IBS.

Cultural differences have also led to difficulties in sub-typing in Asian IBS patients using the Rome criteria. In a rural community-based survey of 2774 adults in India, Ghoshal and Singh²⁵ reported that a large portion (83.0%) of IBS subjects were classified as IBS-mixed using the Rome criteria, based on its’ definition of stool frequency and stool form. However, when the Asian criteria was applied to the same population, only 12.0% were classified as IBS-mixed, with the majority of patients classified as IBS-D.²⁵ Similarly, in the Indian urban (MIIBS) community study, Ghoshal et al²⁰ also demonstrated that using the Asian criteria, compared to the Rome III criteria, reduced the mixed-subtype of IBS from 77.6% to 15.7%. These studies further indicate that cultural perception of symptoms can lead to diagnostic dilemmas in Asian patients with IBS, if only international criteria (eg, Rome criteria) were used.

The true prevalence of functional constipation (FC) among most Asian adults is not known. A recent systemic review of randomised clinical trials in China indicated a FC prevalence of 6%.²⁶ Other Asian countries, including Singapore, Taiwan, and Korea have similarly indicated a prevalence from 3–12% for FC.^27–30 These Asian data contrasts significantly with a reported 14–19% prevalence of FC from North America and Europe, based on systemic reviews (Table 4).^31,32

The difference in prevalence of constipation between the East and the West once again may be due to cultural habits particular to the East. The usual recommended daily dietary fiber intake is 20.0–30.0 g in adults, but the Asian diet traditionally contains a greater amount of fiber than most Western diets. In a recent review article, Rahman et al⁸ compared the mean daily fiber intake of the average Indian adult at 52.0 g to only 13.3 g for the average North American adult. The influence of fiber on intestinal transit is well recognised. Previous experimental work has demonstrated an inverse relationship between dietary fiber and colonic transit time.³³ Furthermore, more fiber results in a greater stool weight, which additionally reduces colonic transit time. In the light of the differences in dietary fiber intake, Rahman et al⁸ additionally showed that the mean intestinal transit time among Northern Indian adults was 39.9 hours compared to 83.4 hours in Caucasian adults (Fig. 1).

Another cultural practice unique to Asians, which may be responsible for less constipation, relates to the defecation posture. The squatting position is a common posture for defecation in Asia, particularly in rural areas, whilst most of the Western population defecate on a sitting toilet. The relevance of these defecating positions relates to the recto-anal angle, which is a major factor in the continence of solid rectal content. In a squatting position, the recto-anal canal straightens and converts the rectoanal canal into a straight canal, facilitating rectal emptying.³⁴ In a study among healthy volunteers, Sikirov³⁵ evaluated time spent for bowel emptying and level of difficulty in defecating between the squatting position and 2 levels of the sitting position. Compared to the standard sitting position, squatting resulted in a shorted mean defecation time (0.9 vs 2.1 minutes) and there was less difficulty (subjectively) in defecation with squatting as well. Hence, these 2 cultural factors of diet and defecating positions, may be partially responsible for the lower rate of constipation in Asians compared to Westerners.

Population-based studies in the West have consistently associated dyspepsia among adults with a lower socio-economic status. Socio-demographic factors such as a lower household income, crowded household, low education level, accommodation with no central heating have been associated with dyspepsia in the United Kingdom and North America.^36,37 However, the situation in Asia appears to be different. Based on the Rome II questionnaire, Mahadeva et al^38,39 had previously conducted large (n = 4000) population-based studies in representative communities in both urban and rural Malaysia. The survey revealed a greater prevalence of dyspepsia (24.5%) among urban adults with a higher socioeconomic status compared to rural adults with a lower socioeconomic background (14.6%). Similarly, Pan et al⁴⁰ had conducted a population-based survey among 2486 subjects within Beijing and in a nearby rural community. IBS, based on the Manning criteria, was prevalent in 10.5% of the urban adults compared to 6.1% in the rural areas (Table 5).

Whilst urban-rural FGID differences in Asia may be due to environmental and socio-demographic factors, cultural variation between urban and rural communities may have a role as well. With rapid urbanization, dietary patterns have changed markedly in many Asian urban populations. In a recent report on dietary transition in rapidly developing East Asian countries, Kim et al⁴¹ highlighted the increasing trend in animal food products, including fat intake, associated with economic prosperity. This increase in dietary fat intake is relevant to FD. In a small sample sized study (FD subjects n = 8, controls n = 8), Pilichiewicz et al⁴² had demonstrated that a high-fat meal induced more symptoms, especially pain and nausea, than an isocaloric high-carbohydrate meal in FD subjects compared to controls.

Apart from dietary variation, differences in lifestyle and mental health may be responsible for the urban-rural divide in Asian FGID. The link between psychological disorders and FGID is well established. Not only do disorders like anxiety lead to the development of FD,⁴³ but a bidirectional pathway between the brain and gut has been indicated.⁴⁴ In the Asian setting, Miwa⁴⁵ was able to demonstrate that Japanese adults with FGID had a higher degree of “stress perception” and “sensitivity to stress”, compared to non-FGID controls, in a population-based study. In the large population-based studies of both urban and rural Malaysia, Mahadeva et al^38,39 had additionally explored health-related quality of life and anxiety presence in FD subjects. Compared to rural adults with FD, urban FD subjects had a greater amount of anxiety (38.0% urban vs 8.8% rural). Furthermore, overall health-related quality of life was significantly lower among urban adults with FD compared to their rural counterparts (Fig. 2). The reason why adults in urban Asia have a greater amount of psychological disorders despite a higher socioeconomic status, compared to the rural population, remains uncertain.

Cultural attitudes to health greatly influence healthcare seeking behavior. This is particularly so for FGIDs, which have symptoms which overlap with organic disease such as GI malignancy. In a population-based study from Bangladesh, Masud et al⁴⁶ and Perveen et al⁴⁷ reported that urban adults with IBS consulted healthcare facilities significantly more than their rural counterparts (65.5% urban vs 34.9% rural). Similarly, two separate studies from India reported that healthcare consultation was greater in urban compared to rural IBS adults (28.9% urban vs 17.2% rural).⁸ In the Indian studies, most IBS subjects sought treatment for their symptoms from either Indian traditional practitioners (Ayurveda) or from homeopathy experts, with only 18.0% seeking attention from modern medical practitioners.⁸ These observations suggest a cultural bias towards traditional practitioners rather than modern, Western-trained healthcare practices, in many parts of the Indian sub-continent (Table 5).

For FD, the Malaysian population-based studies demonstrated that rural adults with dyspepsia were more likely to consult primary and secondary care medical facilities compared to urban adults with dyspepsia (Fig. 3).⁴⁸ Additionally, the urban FD subjects tended to self-medicate with over-the-counter medication or herbal/traditional remedies more than their rural counterparts.⁴⁸ This healthcare seeking behavior appeared to be the reverse for what was reported for IBS in India and Bangladesh. Although cultural attitudes to health may differ between Malaysians and Indians/Bangladeshis, it is likely that variations in healthcare systems may explain the observation regarding FD in Malaysia. In rural Malaysia, primary health-care facilities is easily accessible and heavily subsidised. However, in urban Malaysia, primary healthcare is served predominantly by private clinics, which are more expensive and accessibility is limited due to traffic congestion and a poor public transportation system.⁴⁹ Other cultural factors that have been shown to influence healthcare seeking behavior for FGIDs in Asia include psychological co-morbidity.^50,51 Sleep disturbance, a surrogate marker for psychological co-morbidity, was found to be more prevalent among IBS subjects who consulted healthcare facilities, compared to non-IBS subjects, in a population-based survey in Taiwan.⁴⁶ Anxiety, but not depression, was found to be an independent factor that was associated with healthcare seeking behavior in patients with dyspepsia and IBS in a population-based study from Hong Kong.⁵¹ Although anxiety is not a cultural factor per se, increased anxiety regarding an organic cause for GI symptoms may be more prevalent among ethnic Chinese, as they are known to have more GI malignancy compared to other ethnic groups in Asia.^52,53

Cultural factors pertaining to religion have also been suggested to influence healthcare seeking behavior for FGID. In a community-based survey in a predominantly Muslim society in East Malaysia, Lee et al had demonstrated that Muslim females who were married had more psychosocial symptoms together with FD than their male counterparts, but consultation rates were lower.⁵⁴ Similar observations of a lower female healthcare consultation, despite women having a similar prevalence of IBS as men, have been reported in India, Pakistan and Bangladesh, suggesting a suppressed role of female Muslims.^8,47,55

This review has highlighted the important role of cultural factors on FGID in the East/Asia. Although FD, IBS and FC have been the main FGID conditions discussed in this review, it is likely that other FGID conditions in Asia may be similarly affected by cultural differences. Language, symptom perception and cultural habits strongly influence disease presentation in the East. Dietary habits additionally influence the epidemiology of FGID in the East. Additionally, changing dietary patterns and variation in psychological morbidity, particularly between urban and rural dwellers have led to unique differences in FGID within similar countries. Lastly, cultural preferences for traditional or local remedies and variation in healthcare systems, lead to a diverse healthcare seeking behavior in Asian patients with FGID. All of these factors are important ultimately to manage FGID more effectively in the East, and to reduce the disease burden to both society and healthcare systems. Nevertheless, socio-demographic and socio-cultural data from many parts of Asia are lacking and more information is still required from this vast continent.