Irritable bowel syndrome: an integrated explanatory model for clinical practice

Belgian consensus on irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain related to defaecation or associated with altered stool frequency or consistency. Despite its prevalence, major uncertainties in the diagnostic and therapeutic management persist in clinical practice.

METHODS

A Delphi consensus was conducted by 20 experts from Belgium, and consisted of literature review and voting process on 78 statements. Grading of recommendations, assessment, development and evaluation criteria were applied to evaluate the quality of evidence. Consensus was defined as > 80 % agreement.

RESULTS

Consensus was reached for 50 statements. The Belgian consensus agreed as to the multifactorial aetiology of IBS. According to the consensus abdominal discomfort also represents a cardinal symptom, while bloating and abdominal distension often coexist. IBS needs subtyping based on stool pattern. The importance of a positive diagnosis, relying on history and clinical examination is underlined, while additional testing should remain limited, except when alarm features are present. Explanation of IBS represents a crucial part of patient management. Lifestyle modification, spasmolytics and water-solube fibres are considered first-line agents. The low FODMAP diet, selected probiotics, cognitive behavioural therapy and specific treatments targeting diarrhoea and constipation are considered appropriate. There is a consensus to restrict faecal microbiota transplantation and gluten-free diet, while other treatments are strongly discouraged.

CONCLUSIONS

A panel of Belgian gastroenterologists summarised the current evidence on the aetiology, symptoms, diagnosis and treatment of IBS with attention for the specificities of the Belgian healthcare system.

Impact of Psychological Comorbidity on the Prognosis of Irritable Bowel Syndrome

INTRODUCTION

Psychological comorbidities are associated with irritable bowel syndrome (IBS), but little is known about their cumulative effect on its prognosis. We examined this issue in a longitudinal 12-month follow-up study.

METHODS

We collected complete demographic, symptom, and psychological comorbidity data (anxiety, depression, somatic symptom disorder, perceived stress, and gastrointestinal symptom-specific anxiety) at baseline from 807 adults who met Rome IV criteria for IBS. At 12 months, we collected data regarding IBS symptom severity and impact, consultation behavior, and treatments commenced from 452 individuals successfully followed up. We examined the cumulative effects of psychological comorbidities at baseline on subsequent IBS disease behavior.

RESULTS

At baseline, among the 807 participants, 177 (21.9%) had 1, 139 (17.2%) 2, 103 (12.8%) 3, 89 (11.0%) 4, and 54 (6.7%) 5 psychological comorbidities. IBS symptom severity at baseline increased significantly with the number of psychological comorbidities (72.2% of those with 5 psychological comorbidities reported severe symptoms, vs 29.1% of those with none, P < 0.001). Among 452 (56.0%) participants followed up at 12 months, those with a higher number of psychological comorbidities at baseline were significantly more likely to have seen a gastroenterologist (33.3% of those with 5 psychological comorbidities, vs 21.4% of those with none, P = 0.001), cycle through more treatments (P < 0.0001), to report more severe IBS symptoms (66.7% with 5, vs 24.4% with none, P < 0.001) and continuous abdominal pain (22.1% with none, vs 61.9% with 5, P < 0.001), and to report that symptoms impacted on daily activities ≥50% of the time (90.5% with 5, vs 41.2% with none, P < 0.001).

DISCUSSION

The prognosis of individuals with Rome IV-defined IBS worsens according to incremental increases in psychological comorbidity. This has important clinical and research implications.

Diagnosing Constipation Spectrum Disorders in a Primary Care Setting

Understanding pathophysiological causes of constipation is worthwhile in directing therapy and improving symptoms. This review aims to identify and fill gaps in the understanding of the pathophysiology of constipation, understand its prevalence, review diagnostic tools available to primary care physicians (PCPs), and highlight patients’ expectations for the management of this common spectrum of disorders. Literature searches conducted via PubMed included terms related to constipation, diagnosis, and patient perceptions. Case studies were developed to highlight the differences between patients who may be appropriately managed in the primary care setting and those requiring specialty consultation. Myriad pathophysiological factors may contribute to constipation, including stool consistency, altered intestinal motility, gut microbiome, anorectal abnormalities, as well as behavioral and psychological factors. Common diagnoses of “primary constipation” include slow-transit constipation, defecation disorders, irritable bowel syndrome with constipation, and chronic idiopathic constipation. A detailed medical history should be conducted to exclude alarm features and PCPs should be familiar with pathophysiological factors that cause constipation, available diagnostic tools, alarm signs, and the various classification criteria for constipation subtypes in order to diagnose and treat patients accordingly. PCPs should understand when a referral to a gastroenterologist, anorectal specialist, pelvic floor physical therapist, and/or mental health specialist is appropriate.

Irritable Bowel Syndrome: Food as a Friend or Foe?

Irritable bowel syndrome (IBS) affects 10% to 15% of the population and often is difficult to treat with available pharmacologic agents. Dietary therapies for IBS are of particular interest because up to 90% of IBS patients exclude certain foods to improve their gastrointestinal symptoms. Among the available dietary interventions for IBS, the low FODMAP diet has the greatest evidence for efficacy. Although dietary therapies rapidly are becoming first-line treatment of IBS, gastroenterologists need to be aware of the negative effects of prescribing restrictive diets and red flag symptoms of maladaptive eating patterns.

Depression and Structural Factors Are Associated With Symptoms in Patients of Irritable Bowel Syndrome With Diarrhea

Background/Aims

A strong correlation between depression and irritable bowel syndrome with diarrhea (IBS-D) has been identified. The aim of this study is to identify the correlations among depression, structural factors, gastrointestinal (GI) and extra-GI symptoms, and efficacy of neuromodulators in patients with IBS-D.

Methods

Patients meeting the Rome III Diagnostic Criteria for IBS-D were enrolled. The intestinal symptoms and psychological states were evaluated using IBS-specific symptom questionnaires and Hamilton Depression Rating Scale.

Results

In total, 410 patients with IBS-D were enrolled, 28.8% (118/410) had comorbid depression. Patients with depression did not readily experience improvement in abdominal pain/discomfort after defecation, and had a higher prevalence of passing mucus, overlapping functional dyspepsia, and extra-GI symptoms. The structural factor “mental disorders” significantly correlated with main bowel symptom score and degree of pre-defecation abdominal pain/discomfort. No structural factor significantly correlated with bowel movements or stool form. Patients who had passing mucus, overlapping functional dyspepsia and extra-GI painful symptoms have higher score of “anxiety/somatization.” Patients with sexual dysfunction have higher score of “retardation symptoms.” In total, 28.3% of patients with IBS-D were prescribed neuromodulators. Baseline scores of “anxiety/somatization” and “retardation symptoms” positively correlated with improvement of diarrhea after paroxetine, and “sleep disturbances” positively correlated with improvement of abdominal pain/discomfort and diarrhea after mirtazapine.

Conclusions

Comorbid depression and higher scores of structural factors might aggravate GI and extra-GI symptoms other than bowel movements and stool form. Structural factors of Hamilton Depression Rating Scale correlated with efficacy of paroxetine and mirtazapine in patients with IBS-D.

Evidence-based and mechanistic insights into exclusion diets for IBS

Exclusion diets are becoming increasingly popular in the management of irritable bowel syndrome (IBS). Several mechanisms exist by which food items might cause gastrointestinal symptoms, such as direct osmotic effects of food in the gut lumen, changes to the gut microbiota and immune activation. These effects have been demonstrated in animal models and in human studies, particularly in the case of gluten-free diets and diets low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs). Indeed, randomized controlled trials (RCTs) suggest that gluten-free diets and low-FODMAP diets improve IBS symptoms, and guidelines recommend the latter approach for treating symptoms in some patients with IBS. Designing such RCTs is challenging as participants need to eat so an 'inert' placebo is not an option. Blinding is also an issue with these studies; in the future, new exclusion diets should not advertise what the diet consists of until it is proved to reduce symptoms. In this Review, we outline the advantages and disadvantages of each choice of control group and emphasize the importance of collecting mechanistic data (regarding direct effects of food on the gut lumen, changes in gut microbiota and intestinal inflammation) as well as symptom data in RCTs of exclusion diets in IBS.

Chronic facial pain: different comorbidities and characteristics between neuropathic and nonneuropathic conditions

OBJECTIVE

The aim of this study was to investigate the association between comorbidities and chronic diseases and neuropathic and nonneuropathic orofacial pain diagnoses to suggest subclassifications of disease.

STUDY DESIGN

This was a cross-sectional, retrospective, case-control study. We evaluated 174 patients with orofacial pain and 132 controls by using a systematic protocol that consisted of medical history and demographic, pain, and orofacial characteristics. Patients were grouped according to their diagnosis-neuropathic or non-neuropathic pain; medical comorbidities; and exclusion criteria. Analyses included Z-score normalization, χ² test, Fisher's exact test, 1-way analysis of variance (ANOVA), Student t test, Pearson's correlation coefficient, 2-step clustering, and logistic regression at 95% confidence level.

RESULTS

Functional chronic diseases were prevalent and correlated with pain and orofacial features. Three groups were identified in the cluster analysis: neuropathic facial pain, other orofacial pain syndromes, and fibromyalgia/temporomandibular disorders (TMDs). Logistic regression showed that hypothyroidism and gastritis were predictors for nonneuropathic orofacial conditions. Psychiatric diseases and gastritis were more prevalent among patients with generalized pain syndromes and TMDs and less prevalent among patients with neuropathic pain.

CONCLUSIONS

Functional comorbidities were associated with orofacial and dental features and may correspond to multimorbidity states in patients with chronic orofacial pain. The findings support the hypothesis that nonneuropathic orofacial pain syndromes could be functional disorders.

Can Sertraline and Nortriptyline Protect the Neurons in Submucosal and Myenteric Plexuses of Rat's Colon Against Stress?

BACKGROUND

The colon is partly controlled by myenteric and submucosal plexuses, which respond to stress and lead to some gastrointestinal disorders. These plexuses play roles in irritable bowel syndrome. Patients suffering from this syndrome can be treated with some antidepressants, including sertraline and nortriptyline.

AIMS

The primary aim of study was to compare the effect of a sertraline and a nortriptyline on the structural changes of the enteric neurons after stress exposure in both sexes. The secondary objectives were to evaluate the effects of stress on the submucosal and myenteric plexuses.

METHODS

Male and female Sprague-Dawley rats were assigned to four subgroups. The first subgroup received no stress. The other three subgroups received chronic variable stress (CVS) and were given phosphate buffer, sertraline (10 mg/kg/day), or nortriptyline (10 mg/kg/day). After 45 days, the neuron number in their colon plexuses was estimated using the stereologic method.

RESULTS

The number of neurons increased by 40-51% in the submucosal plexus and by 57-69% in the myenteric plexus in the CVS group compared with the control group (p < 0.002) without any sex preference. The increment was significantly higher in the myenteric plexus than in the submucosal plexus (p < 0.05). Moreover, co-treatment of stressed rats with sertraline and nortriptyline could prevent the cellular hyperplasia of the plexuses, with more effective action for sertraline (p < 0.02).

CONCLUSIONS

Stress exposure for 45 days induced hyperplasia of the colon's enteric plexuses in both sexes. However, these drugs could prevent the changes, with a more effective action for sertraline.

Epidemiology and risk factors for bipolar disorder

Bipolar disorder is a multifactorial illness with uncertain aetiology. Knowledge of potential risk factors enables clinicians to identify patients who are more likely to develop bipolar disorder, which directs further investigation, follow up and caution when prescribing. Ideally, identifying directly causative factors for bipolar disorder would enable intervention on an individual or population level to prevent the development of the illness, and improve outcomes through earlier treatment. This article reviews the epidemiology of bipolar disorder, along with putative demographic, genetic and environmental risk factors, while assessing the strength of these associations and to what extent they might be said to be 'causative'. While numerous genetic and environmental risk factors have been identified, the attributable risk of individual factors is often small, and most are not specific to bipolar disorder but are associated with several mental illnesses. Therefore, while some genetic and environmental factors have strong evidence supporting their association with bipolar disorder, fewer have sufficient evidence to establish causality. There is increasing interest in the role of specific gene-environment interactions, as well as the mechanisms by which risk factors interact to lead to bipolar disorder.

Recent advances in pharmacological research on the management of irritable bowel syndrome

Irritable bowel syndrome (IBS), a common gastrointestinal (GI) disorder, is associated with various factors, including lifestyle, infection, stress, intestinal flora, and related diseases. The pharmacotherapeutic stimulation of receptors and downstream signaling pathways is effective in reducing IBS symptoms; however, it is still associated with adverse effects. Various receptors related to GI motility and visceral hypersensitivity should be considered to enhance the benefit/risk ratio of IBS treatments. This review discusses recent pharmacological advances in IBS management. Several receptors related to GI motility and abdominal pain are investigated in various angles. 5-Hydroxytryptamine (5-HT) is an important neurotransmitter that activates the colonic mucosal 5-HT₄ receptor without causing severe cardiovascular adverse effects. The clinical potential of ramosetron for diarrhea-predominant IBS has been suggested because of a lower risk of ischemic colitis than conventional 5-HT₃ receptor antagonists. Toll-like receptors (TLRs), especially TLR2 and TLR4, show a significant effect on the post-infection symptoms and lipopolysaccharide-mediated regulation of GI motility. Histamine is a well-known nitrogenous compound that regulates inflammatory responses and visceral hypersensitivity. Histamine 1 receptor-mediated sensitization of the transient receptor potential vanilloid 1 is associated with IBS. Pharmacological approaches based on these signaling pathways could be useful in the development of novel IBS treatments.

Cognitive behavioral therapy for irritable bowel syndrome: the effects on state and trait anxiety and the autonomic nervous system during induced rectal distensions - An uncontrolled trial

BACKGROUND AND AIMS

Irritable bowel syndrome (IBS), is a common multifactorial gastrointestinal disorder linked to disturbances in the microbe gut-brain axis. Cognitive behavioral therapy (CBT), in face-to-face format has showed promising results on IBS and its associated psychological symptoms. The present study explored for the first time if CBT for IBS affects the autonomic nervous system (ANS) during experimentally induced visceral pain and cognitive stress, respectively. The levels of state and trait anxiety, current and perceived stress were also evaluated.

METHODS

In this uncontrolled trial, individual CBT was performed in face-to-face format for 12 weeks in 18 subjects with IBS. Heart rate variability and skin conductance were measured during experimentally induced visceral pain and during a cognitive task (Stroop color-word test), before and after intervention. The levels of state and trait anxiety as well as self-rated current and perceived stress were also measured before and after the intervention.

RESULTS

CBT did not affect ANS activity during experimentally induced visceral pain and cognitive stress. The sympathetic activity was high, typical for IBS and triggered during both visceral pain and cognitive stress. The levels of state and trait anxiety significantly decreased after the intervention. No significant changes in self-rated current or perceived stress were found.

CONCLUSIONS

Results suggest that face-to-face CBT for IBS improved anxiety- a key psychological mechanism for the IBS pathophysiology, rather than the autonomic stress response to experimentally induced visceral pain and cognitive stress, respectively.

IMPLICATIONS

This study indicates that IBS patients present high levels of stress and difficulties coping with anxiety and ANS activity during visceral pain and a cognitive stress test, respectively. These manifestations of IBS are however not targeted by CBT, and do not seem to be central for the study participants IBS symptoms according to the current and our previous study. Face-to-face CBT for IBS, it does not seem to affect modulation of ANS activity in response to induced visceral pain or cognitive stress. Instead, face-to-face CBT decreased levels of state and trait anxiety. Implications for further studies include that anxiety seems to be important in the IBS pathophysiology, and needs further scientific attention. This is in line with the fear-avoidance model which suggests that anxious responses to pain and discomfort drive hypervigilance to, and (behavioral) avoidance of, symptom provoking stimuli and vice versa. Catastrophic cognitions, hypervigilance and avoidant behavioral responses are proposed to produce vicious circles that withhold and exacerbate pain-related symptoms and disability, and lead to lower quality of life. Larger scale studies of potential autonomic changes are needed in order to elucidate which mechanisms elicit its effects in face-to-face CBT for IBS, and provide new avenues in understanding the pathophysiology of IBS.

Irritable bowel syndrome diagnosis and management: A simplified algorithm for clinical practice

BACKGROUND

Effective management of irritable bowel syndrome (IBS), a common functional gastrointestinal disorder, can be challenging for physicians because of the lack of simple diagnostic tests and the wide variety of treatment approaches available.

OBJECTIVE

The objective of this article is to outline a simple algorithm for day-to-day clinical practice to help physicians navigate key stages to reaching a positive IBS diagnosis and guidance on how to prioritise the use of specific management strategies.

METHODS

This algorithm was based on the opinion of an expert panel evaluating current evidence.

RESULTS

The key principles forming the foundation of this evidence-supported algorithm are: confidently naming and explaining an IBS diagnosis for the patient, followed by assessment of key patient characteristics likely to influence the choice of therapy, such as predominant symptoms, and exploring the patient agenda and preferences. Consultation should always include education and reassurance with an explanatory model of IBS tailored to the patient. Individualised lifestyle changes, dietary modifications, pharmacological therapies, psychological strategies or a combination of interventions may be used to optimise treatment for each patient.

CONCLUSION

The simple visual tools developed here navigate the key stages to reaching a positive diagnosis of IBS, and provide a stepwise approach to patient-centred management targeted towards the most bothersome symptoms. Establishing a strong patient-physician relationship is central to all stages of the patient journey from diagnosis to effective management.

Bifidobacterium-Rich Fecal Donor May Be a Positive Predictor for Successful Fecal Microbiota Transplantation in Patients with Irritable Bowel Syndrome

BACKGROUND/AIMS

Dysbiosis is associated with various systemic disorders including irritable bowel syndrome (IBS). Fecal microbiota transplantation (FMT) might restore intestinal microbial balance. The study aimed to determine the safety and efficacy of FMT in IBS patients, as well as also positive predictors for FMT.

METHODS

This was a single-arm, open-label study. Eligible patients were diagnosed based on Rome III Diagnostic Criteria. Fecal materials were administered to the patient via colonoscopy. The primary end point was a change in the Bristol stool form scale at 4 weeks after FMT. Recovery to types 3-4 was considered a clinical response. The secondary end point was a change in intestinal microbiota and psychological status using the Hamilton Rating Scale.

RESULTS

Ten patients were enrolled. Six patients achieved a clinical response. The diversity of patients 4 weeks after FMT increased significantly compared with patients before FMT, and that of responding patients was significantly higher than non-responder patients. The abundance of Bifidobacterium in effective donors was significantly higher than in ineffective donors and patients. Psychological status of all patients was significantly improved after FMT.

CONCLUSIONS

FMT for patients with IBS is safe, and relatively effective. Bifidobacterium-rich fecal donor may be a positive predictor for successful FMT. Key Summary: (1) Dysbiosis is associated with various gastrointestinal disorders including IBS. (2) FMT has potential to restore intestinal microbial balance. (3) We showed that FMT improved stool form and psychological status of IBS patients. (4) Bifidobacterium-rich donor efficiently induced symbiosis in IBS patients.

Use of Rome criteria for the diagnosis of irritable bowel syndrome in primary care: a survey among European countries

BACKGROUND AND OBJECTIVES

The majority of patients with irritable bowel syndrome (IBS) are diagnosed and treated in primary care. The aim of this study was to investigate the implementation of the Rome criteria in daily primary care clinical practice and adherence of general practitioners (GPs) to recommended diagnostic approaches for IBS.

PATIENTS AND METHODS

A survey consisting of 18 questions was distributed across 11 European countries and was used to assess GPs' diagnostic approach of IBS, the use of Rome criteria in daily practice and GPs' perspective on the aetiology of the disorder.

RESULTS

Overall, 185 GPs completed the survey. In daily clinical practice, 32% of GPs reported that they usually make a positive diagnosis on the basis of symptoms only, whereas 36% of GPs reported regular use of the Rome criteria to diagnose IBS. Furthermore, 62% of the responders reported that they applied additional diagnostics, such as blood tests, 31% found it necessary to perform endoscopy to make a positive diagnosis of IBS and 29% referred patients with IBS to a specialist. Psychological factors were the most frequently selected potential aetiological factor of IBS (88% of GPs). Overall, 52% of GPs reported systematically including questions on psychological symptoms in the assessment of history of IBS.

CONCLUSION

Only about one-third of GPs regularly used the Rome criteria to diagnose IBS. In daily primary care practice, IBS largely remains a diagnosis of exclusion. This has implications in terms of GPs' specialty training and questions the applicability of IBS guidelines in daily care, which advocate an early, positive, symptom-based diagnosis.

Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses

OBJECTIVES

The pathophysiology of bipolar disorder is likely to involve both genetic and environmental risk factors. In our study, we aimed to perform a systematic search of environmental risk factors for BD. In addition, we assessed possible hints of bias in this literature, and identified risk factors supported by high epidemiological credibility.

METHODS

We searched the Pubmed/MEDLINE, EMBASE and PsycInfo databases up to 7 October 2016 to identify systematic reviews and meta-analyses of observational studies that assessed associations between putative environmental risk factors and BD. For each meta-analysis, we estimated its summary effect size by means of both random- and fixed-effects models, 95% confidence intervals (CIs), the 95% prediction interval, and heterogeneity. Evidence of small-study effects and excess of significance bias was also assessed.

RESULTS

Sixteen publications met the inclusion criteria (seven meta-analyses and nine qualitative systematic reviews). Fifty-one unique environmental risk factors for BD were evaluated. Six meta-analyses investigated associations with a risk factor for BD. Only irritable bowel syndrome (IBS) emerged as a risk factor for BD supported by convincing evidence (k=6; odds ratio [OR]=2.48; 95% CI=2.35-2.61; P<.001), and childhood adversity was supported by highly suggestive evidence. Asthma and obesity were risk factors for BD supported by suggestive evidence, and seropositivity to Toxoplasma gondii and a history of head injury were supported by weak evidence.

CONCLUSIONS

Notwithstanding that several environmental risk factors for BD were identified, few meta-analyses of observational studies were available. Therefore, further well-designed and adequately powered studies are necessary to map the environmental risk factors for BD.

The role of alexithymia and gastrointestinal-specific anxiety as predictors of treatment outcome in irritable bowel syndrome

In a previous investigation irritable bowel syndrome (IBS) was associated more to alexithymia than gastrointestinal-specific anxiety (GSA). In this study their independent contribution in predicting treatment outcome was longitudinally investigated. Consecutive 150 IBS patients were evaluated for IBS symptoms, alexithymia, GSA, and psychological distress with validated scales after as-usual treatment for 6-12months. The primary treatment outcome was improvement measured with the IBS-Severity Scoring System that showed 111 patients who improved and 39 who did not improve. Improvement was associated to both alexithymia (d=1.27) and GSA (d=4.63) but only alexithymia showed overtime stability by hierarchical regression, controlled for co-variables. A series of logistic and linear regressions showed that baseline alexithymia, but not GSA, independently predicted both post-treatment improvement status (Cox & Snell R²=0.15; overall classification rate=74%) and symptom change (23% of explained variance). Although alexithymia and GSA were closely related IBS symptoms, only alexithymia was found to be a stable trait and a stronger predictor of treatment outcome than GSA. Since no treatment was established to be definitely effective for IBS, clinicians might improve treatment outcome by identifying patients with high alexithymia, attempting to improve their coping skills, emotional regulation, and affective awareness.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease with a high population prevalence. The disorder can be debilitating in some patients, whereas others may have mild or moderate symptoms. The most important single risk factors are female sex, younger age and preceding gastrointestinal infections. Clinical symptoms of IBS include abdominal pain or discomfort, stool irregularities and bloating, as well as other somatic, visceral and psychiatric comorbidities. Currently, the diagnosis of IBS is based on symptoms and the exclusion of other organic diseases, and therapy includes drug treatment of the predominant symptoms, nutrition and psychotherapy. Although the underlying pathogenesis is far from understood, aetiological factors include increased epithelial hyperpermeability, dysbiosis, inflammation, visceral hypersensitivity, epigenetics and genetics, and altered brain-gut interactions. IBS considerably affects quality of life and imposes a profound burden on patients, physicians and the health-care system. The past decade has seen remarkable progress in our understanding of functional bowel disorders such as IBS that will be summarized in this Primer.

Altered gastrointestinal microbiota in irritable bowel syndrome and its modification by diet: probiotics, prebiotics and the low FODMAP diet

Irritable bowel syndrome (IBS) is a functional bowel disorder characterised by abdominal pain or discomfort with disordered defecation. This review describes the role of the gastrointestinal (GI) microbiota in the pathogenesis of IBS and how dietary strategies to manage symptoms impact on the microbial community. Evidence suggests a dysbiosis of the luminal and mucosal colonic microbiota in IBS, frequently characterised by a reduction in species of Bifidobacteria which has been associated with worse symptom profile. Probiotic supplementation trials suggest intentional modulation of the GI microbiota may be effective in treating IBS. A smaller number of prebiotic supplementation studies have also demonstrated effectiveness in IBS whilst increasing Bifidobacteria. In contrast, a novel method of managing IBS symptoms is the restriction of short-chain fermentable carbohydrates (low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet). Studies consistently demonstrate clinical effectiveness of the low FODMAP diet in patients with IBS. However, one unintentional consequence of this dietary intervention is its impact on the microbiota. This leads to an interesting paradox; namely, increasing luminal Bifidobacteria through probiotic supplementation is associated with a reduction in IBS symptoms while in direct conflict to this, the low FODMAP diet has clinical efficacy but markedly reduces luminal Bifidobacteria concentration. Given the multifactorial aetiology of IBS, the heterogeneity of symptoms and the complex and diverse nature of the microbiome, it is probable that both interventions are effective in patient subgroups. However combination treatment has never been explored and as such, presents an exciting opportunity for optimising clinical management, whilst preventing potentially deleterious effects on the GI microbiota.