The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis

Irritable bowel syndrome, the microbiota and the gut-brain axis

Irritable bowel syndrome is a common functional gastrointestinal disorder and it is now evident that irritable bowel syndrome is a multi-factorial complex of changes in microbiota and immunology. The bidirectional neurohumoral integrated communication between the microbiota and the autonomous nervous system is called the gut-brain-axis, which integrates brain and GI functions, such as gut motility, appetite and weight. The gut-brain-axis has a central function in the perpetuation of irritable bowel syndrome and the microbiota plays a critical role. The purpose of this article is to review recent research concerning the epidemiology of irritable bowel syndrome, influence of microbiota, probiota, gut-brain-axis, and possible treatment modalities on irritable bowel syndrome.

Irritable Bowel Syndrome and Female Patients

Irritable bowel syndrome is probably the most common functional gastrointestinal disorder and is characterized by abdominal pain along with altered bowel function. It is a disorder of female predominance. This article focuses on how being female influences the pathophysiology, diagnosis, management, and treatment of this common disorder and discusses the evidence and important controversies related to these areas.

Addressing the Role of Food in Irritable Bowel Syndrome Symptom Management

Patients with irritable bowel syndrome (IBS) have often associated the worsening of symptoms with specific foods. Research is starting to catch up with what patients have reported about food interaction and their symptoms and the role of diet is being increasingly recognized for the management of IBS. Clinical guidance for nurse practitioners can be challenging due to limited data and guideline consensus along with the nuances of symptoms associated with IBS subtypes. This article summarizes some of the key themes and dietary recommendations by various gastrointestinal (GI) organizations, public health agencies, and dietary associations. By addressing the relevance of diet for symptom alleviation, nurse practitioners are able to better support patients and collaborate with dietitians to improve symptom management.

Prebiotics and synbiotics: dietary strategies for improving gut health

PURPOSE OF REVIEW

A wide range of dietary carbohydrates, including prebiotic food ingredients, fermentable fibers, and milk oligosaccharides, are able to produce significant changes in the intestinal microbiota. These shifts in the microbial community are often characterized by increased levels of bifidobacteria and lactobacilli. More recent studies have revealed that species of Faecalibacterium, Akkermansia, and other less well studied members may also be enriched. We review the implications of these recent studies on future design of prebiotics and synbiotics to promote gastrointestinal health.

RECENT FINDINGS

Investigations assessing the clinical outcomes associated with dietary modification of the gut microbiota have shown systemic as well as specific health benefits. Both prebiotic oligosaccharides comprised of a linear arrangement of simple sugars, as well as fiber-rich foods containing complex carbohydrates, have been used in these trials. However, individual variability and nonresponding study participants can make the outcome of dietary interventions less predictable. In contrast, synergistic synbiotics containing prebiotics that specifically stimulate a cognate probiotic provide additional options for personalized gut therapies.

SUMMARY

This review describes recent research on how prebiotics and fermentable fibers can influence the gut microbiota and result in improvements to human health.

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.

Bowel Disorders

Functional bowel disorders are highly prevalent disorders found worldwide. These disorders have the potential to affect all members of society, regardless of age, gender, race, creed, color or socioeconomic status. Improving our understanding of functional bowel disorders (FBD) is critical as they impose a negative economic impact to the global health care system in addition to reducing quality of life. Research in the basic and clinical sciences during the past decade has produced new information on the epidemiology, etiology, pathophysiology, diagnosis and treatment of FBDs. These important findings created a need to revise the Rome III criteria for FBDs, last published in 2006. This manuscript classifies the FBDs into five distinct categories: irritable bowel syndrome (IBS); functional constipation (FC); functional diarrhea (FDr); functional abdominal bloating/distention (FAB/D); and unspecified FBD (U-FBD). Also included in this article is a new sixth category, opioid induced constipation (OIC) which is distinct from the functional bowel disorders (FBDs). Each disorder will first be defined, followed by sections on epidemiology, rationale for changes from prior criteria, clinical evaluation, physiologic features, psychosocial features and treatment. It is the hope of this committee that this new information will assist both clinicians and researchers in the decade to come.

The Science, Evidence, and Practice of Dietary Interventions in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a highly prevalent disorder that is characterized by symptoms of abdominal pain, bloating, constipation, and/or diarrhea. The diagnosis can be made using Rome III criteria or published guidelines after taking a thoughtful history, excluding warning signs, and performing a careful physical examination. Limited testing (ie, complete blood count and C-reactive protein level) may be useful in appropriate patients. A number of pharmacologic options are available, although many patients fail to respond to pharmacologic therapy. Although several IBS diets frequently are recommended, data supporting their use are limited. This article provides a rationale as to why specific diets might improve IBS symptoms and evaluates published trials.

The role of fiber supplementation in the treatment of irritable bowel syndrome: a systematic review and meta-analysis

Irritable bowel syndrome (IBS) is a functional bowel disorder associated with a wide variety of clinical symptoms. The use of fiber in treatment of IBS is well established, but recent reviews have shown conflicting evidence. The aim of our review was to study the effects of fiber (soluble and insoluble) on the symptoms of IBS. Medline, EMBASE, Cochrane Central, CINAHL, LILACS, and ClinicalTrials.gov were searched for appropriate studies. Two reviewers screened the title/abstract and full text against the inclusion criterion - that is, randomized control trials/crossover studies that compare fiber with placebo for its effect on IBS in an outpatient setting. Independent double data extraction was performed across multiple fields. An assessment of the risk of bias and tests for heterogeneity were carried out, along with a meta-analysis of the outcomes of interest. The search yielded 4199 unique records: 121 were selected after title/abstract screening and 22 after full screening. There was moderate clinical, methodological, and statistical heterogeneity across studies, with a moderate risk of bias. Overall, there was a significant improvement in global assessment of symptoms among those randomized to fiber [risk ratio: 1.27; 95% confidence interval (CI): 1.05-1.54]. Soluble fiber improved assessment of symptoms (risk ratio 1.49; 95% CI: 1.09-2.03), as well as the abdominal pain score (mean difference: -1.84; 95% CI: -2.72 to -0.97), with insoluble fiber not showing improvement in any outcome. Soluble fiber appears to improve symptoms of IBS, whereas there is no evidence for recommending insoluble fiber for IBS.

Irritable bowel syndrome: modern concepts and management options

Irritable bowel syndrome is the most common functional gastrointestinal disorder, manifesting as abdominal pain/discomfort and altered bowel function. Despite affecting as many as 20% of adults, a lack of understanding of etiopathogenesis and evaluation strategies results in diagnostic uncertainty, and in turn frustration of both the physician and the patient. This review summarizes the current literature on the diagnosis and management of irritable bowel syndrome, with attention to evidence-based approaches. A 4-step treatment strategy that has been used successfully in our tertiary referral practice is presented and should lead to successful therapeutic outcomes in the majority of patients with irritable bowel syndrome.

Dietary intake of soluble fiber and risk of islet autoimmunity by 5 y of age: results from the TEDDY study

BACKGROUND

Deficient soluble fiber intake has been suggested to dysregulate the immune response either directly or through alterations of the microbial composition in the gut.

OBJECTIVE

We hypothesized that a high intake of dietary soluble fiber in early childhood decreases the risk of type 1 diabetes (T1D)-associated islet autoimmunity.

DESIGN

We analyzed 17,620 food records collected between age 9 and 48 mo from 3358 children from the United States and Germany prospectively followed in the TEDDY (The Environmental Determinants of Diabetes in the Young) study. HRs for the development of any/multiple islet autoantibodies (242 and 151 events, respectively) and T1D (71 events) by soluble fiber intake were calculated in Cox regression models and adjusted for potential confounders.

RESULTS

There were no statistically significantly protective associations observed between a high intake of soluble fiber and islet autoimmunity or T1D. For example, the adjusted HRs (95% CIs) for high intake (highest compared with lowest quintile) at age 12 mo were 0.90 (0.55, 1.45) for any islet autoantibody, 1.20 (0.69, 2.11) for multiple islet autoantibodies, and 1.24 (0.57, 2.70) for T1D. In analyzing soluble fiber intake as a time-varying covariate, there were also no short-term associations between soluble fiber intake and islet autoimmunity development, with adjusted HRs of 0.85 (0.51, 1.42) for high intake and development of any islet autoantibody, for example.

CONCLUSION

These results indicate that the intake level of dietary soluble fiber is not associated with islet autoimmunity or T1D in early life.

Systematic review: dietary fibre and FODMAP-restricted diet in the management of constipation and irritable bowel syndrome

BACKGROUND

Dietary fibre supplements have been advocated for the management of chronic constipation (CC) and irritable bowel syndrome (IBS). Recently, a fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) restricted diet has been recommended for IBS.

AIM

To systematically examine recent evidence for dietary interventions with fibre in CC and IBS and FODMAP-restricted diet in IBS, and provide recommendations.

METHODS

We searched PUBMED, MEDLINE, OVID and COCHRANE databases from 2004 to 2014. Published studies in adults with CC and IBS and constipation-predominant IBS (IBS-C) that compared fibre with placebo/alternative and FODMAP-restricted diet with alternative were included.

RESULTS

Of 550 potentially eligible clinical trials on fibre, 11 studies were found and of 23 potentially eligible studies on FODMAPs, six were found. A meta-analysis was not performed due to heterogeneity and methodological quality. Fibre was beneficial in 5/7 studies in CC and 3/3 studies in IBS-C. FODMAP-restricted diet improved overall IBS symptoms in 4/4 and IBS-C symptoms in 1/3 studies and three studies did not meet inclusion criteria. There were significant disparities in subject selection, interventions and outcome assessments in both fibre and FODMAPs studies.

CONCLUSIONS

Fibre supplementation is beneficial in mild to moderate CC and IBS-C, although larger, more rigorous and long-term RCTs are needed (Fair evidence-Level II, Grade B). Although the FODMAP-restricted diet may be effective in short-term management of selected patients with IBS (Fair evidence-Level II, Grade C) and IBS-C (Poor evidence-Level III, Grade C), more rigorous trials are needed to establish long-term efficacy and safety, particularly on colonic health and microbiome.

Food components and irritable bowel syndrome

Ingestion of food has long been linked with gut symptoms, and there is increasing interest in using diet in the management of patients with irritable bowel syndrome (IBS). The West has developed an intense interest in specialized, restrictive diets, such as those that target multiple food groups, avoid gluten, or reduce fermentable oligo-, di-, and mono-saccharides and polyols. However, most gastroenterologists are not well educated about diets or their effects on the gut. It is important to understand the various dietary approaches, their putative mechanisms, the evidence that supports their use, and the benefits or harm they might produce. The concepts behind, and delivery of, specialized diets differ from those of pharmacologic agents. High-quality research is needed to determine the efficacy of different dietary approaches and the place of specific strategies.

Diet and irritable bowel syndrome

PURPOSE

of review Those who suffer from irritable bowel syndrome (IBS) have long reported the frequent precipitation of their symptoms in relation to food ingestion and have often been convinced that certain foods were especially problematic. However, until very recently, research on the responses to food or individual dietary constituents, in IBS, has been scarce. This review addresses recent literature on diet and IBS.

RECENT FINDINGS

The complexity of food-symptom interactions in IBS is being revealed in recent and ongoing research. Such studies have revealed the variable effects of fibre in IBS and the susceptibility of IBS individuals to the ingestion of poorly digested and absorbed carbohydrates. The latter has led to the widespread adoption of the low-fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) diet. Less certain is the role of another widely adopted dietary strategy, gluten restriction. Diet-microbe interactions are critical to the homeostasis of the gut microbiome in health and may well be disturbed in disease; enthusiasm continues, therefore, for the use of probiotics in IBS.

SUMMARY

Food is a common precipitant of symptoms in IBS and recent research has focused on the role(s) of individual dietary constituents in IBS and on fibre, FODMAPs, gluten and probiotics, in particular. Each may have a role in certain IBS sufferers.

IBS-like symptoms in patients with ulcerative colitis

Ulcerative colitis (UC) and irritable bowel syndrome (IBS) are chronic gastrointestinal disorders that, until recently, have been considered dichotomous conditions falling on either side of a functional-organic divide. However, persistent gastrointestinal symptoms, akin to those of IBS, are observed in up to one in three patients with quiescent UC. Whether these lower gastrointestinal symptoms are secondary to coexistent IBS or occult UC disease activity is uncertain, but when objective evidence of disease activity is lacking, escalation of conventional pharmacotherapy in such patients is often ineffective. The etiologies of both UC and IBS remain unclear, but dysregulation of the enteric nervous system, an altered microbiome, low-grade mucosal inflammation, and activation of the brain–gut axis is common to both; this suggests that some overlap between the two conditions is plausible. How best to investigate and manage IBS-type symptoms in UC patients remains unclear. Studies that have assessed patients with UC who meet criteria for IBS for subclinical inflammation have been conflicting in their results. Although evidence-based treatments for IBS exist, their efficacy in UC patients reporting these types of symptoms remains unclear. Given the disturbances in gut microbiota in UC, and the possible role of the brain–gut axis in the generation of such symptoms, treatments such as probiotics, fecal transfer, antidepressants, or psychological therapies would seem logical approaches to use in this group of patients. However, there are only limited data for all of these therapies; this suggests that randomized controlled trials to investigate their efficacy in this setting may be warranted.

Intestinal microbiota and diet in IBS: causes, consequences, or epiphenomena?

Irritable bowel syndrome (IBS) is a heterogeneous functional disorder with a multifactorial etiology that involves the interplay of both host and environmental factors. Among environmental factors relevant for IBS etiology, the diet stands out given that the majority of IBS patients report their symptoms to be triggered by meals or specific foods. The diet provides substrates for microbial fermentation, and, as the composition of the intestinal microbiota is disturbed in IBS patients, the link between diet, microbiota composition, and microbial fermentation products might have an essential role in IBS etiology. In this review, we summarize current evidence regarding the impact of diet and the intestinal microbiota on IBS symptoms, as well as the reported interactions between diet and the microbiota composition. On the basis of the existing data, we suggest pathways (mechanisms) by which diet components, via the microbial fermentation, could trigger IBS symptoms. Finally, this review provides recommendations for future studies that would enable elucidation of the role of diet and microbiota and how these factors may be (inter)related in the pathophysiology of IBS.

Optimal management of constipation associated with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common chronic functional disorder of the gastrointestinal tract, meanly characterized by recurrent abdominal pain or discomfort and altered bowel habit. It is a complex disorder involving biological, environmental, and psychosocial factors. The diagnosis is achieved according to the Rome III criteria provided that organic causes have been excluded. Although IBS does not constitute a life-threatening condition, it has a remarkable prevalence and profoundly reduces the quality of life with burdening socioeconomic costs. One of the principal concerns about IBS is the lack of effective therapeutic options. Up to 40% of patients are not satisfied with any available medications, especially those suffering from chronic constipation. A correct management of IBS with constipation should evolve through a global approach focused on the patient, starting with careful history taking in order to assess the presence of organic diseases that might trigger the disorder. Therefore, the second step is to examine lifestyle, dietary habits, and psychological status. On these bases, a step-up management of disease is recommended: from fiber and bulking agents, to osmotic laxative drugs, to new molecules like lubiprostone and linaclotide. Although new promising tools for relief of bowel-movement-related symptoms are being discovered, a dedicated doctor-patient relationship still seems to be the key for success.