IBS is one of the most common functional gastrointestinal disorders worldwide and is thought to be the result of disturbed neural function along the brain-gut axis. The mechanisms behind this ...disturbance are not clear, but important roles for low-grade inflammation and immunological alterations in the development of symptoms compatible with IBS have become evident. The development of long-standing gastrointestinal symptoms after infectious gastroenteritis and patients with IBD in remission frequently having functional gastrointestinal symptoms support this hypothesis. An increased innate immune activity in the intestinal mucosa and in blood is found in subpopulations of patients with IBS. Mast cells and monocytes seem to be particularly important. In addition, studies have demonstrated that IBS may be associated with an activated adaptive immune response. Increased epithelial barrier permeability and an abnormal gut flora might lead to increased activation of the intestinal immune system. Functional and anatomical evidence for abnormal neuroimmune interactions has been found in patients with IBS. The link between immune alterations and severity of gastrointestinal symptoms and the positive effect of anti-inflammatory treatments in IBS further highlight the relevance of neuroimmune interactions in this condition.
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.
Even though irritable bowel syndrome (IBS) has been known for more than 150 years, it still remains one of the research challenges of the 21st century. According to the current diagnostic Rome IV ...criteria, IBS is characterized by abdominal pain associated with defecation and/or a change in bowel habit, in the absence of detectable organic causes. Symptoms interfere with the daily life of patients, reduce health-related quality of life and lower the work productivity. Despite the high prevalence of approximately 10%, its pathophysiology is only partly understood and seems multifactorial. However, many patients report symptoms to be meal-related and certain ingested foods may generate an exaggerated gastrointestinal response. Patients tend to avoid and even exclude certain food products to relieve their symptoms, which could affect nutritional quality. We performed a narrative paper review of the existing and emerging evidence regarding dietary management of IBS patients, with the aim to enhance our understanding of how to move towards an individualized dietary approach for IBS patients in the near future.
Background & Aims A diet with reduced content of fermentable short-chain carbohydrates (fermentable oligo-, di-, monosaccharides, and polyols FODMAPs) has been reported to be effective in the ...treatment of patients with irritable bowel syndrome (IBS). However, there is no evidence of its superiority to traditional dietary advice for these patients. We compared the effects of a diet low in FODMAPs with traditional dietary advice in a randomized controlled trial of patients with IBS. Methods We performed a multi-center, parallel, single-blind study of 75 patients who met Rome III criteria for IBS and were enrolled at gastroenterology outpatient clinics in Sweden. Subjects were randomly assigned to groups that ate specific diets for 4 weeks—a diet low in FODMAPs (n = 38) or a diet frequently recommended for patients with IBS (ie, a regular meal pattern; avoidance of large meals; and reduced intake of fat, insoluble fibers, caffeine, and gas-producing foods, such as beans, cabbage, and onions), with greater emphasis on how and when to eat rather than on what foods to ingest (n = 37). Symptom severity was assessed using the IBS Symptom Severity Scale, and patients completed a 4-day food diary before and at the end of the intervention. Results A total of 67 patients completed the dietary intervention (33 completed the diet low in FODMAPs, 34 completed the traditional IBS diet). The severity of IBS symptoms was reduced in both groups during the intervention ( P < .0001 in both groups before vs at the end of the 4-week diet), without a significant difference between the groups ( P = .62). At the end of the 4-week diet period, 19 patients (50%) in the low-FODMAP group had reductions in IBS severity scores ≥50 compared with baseline vs 17 patients (46%) in the traditional IBS diet group ( P = .72). Food diaries demonstrated good adherence to the dietary advice. Conclusions A diet low in FODMAPs reduces IBS symptoms as well as traditional IBS dietary advice. Combining elements from these 2 strategies might further reduce symptoms of IBS. ClinicalTrials.gov ID NCT02107625.
The aetiology and pathology of IBS, a functional bowel disorder thought to lack an organic cause, is largely unknown. However, studies suggest that various features, such as altered composition of ...the gut microbiota, together with increased intestinal permeability, a changed balance in the enteroendocrine system and a dysregulated immune system in the gut, most likely have an important role in IBS. Exactly how these entities act together and give rise to symptoms is still unknown, but an altered gut microbiota composition could lead to dysregulation of the intestinal barrier as well as the enteroendocrine and the immune systems, which (through interactions with the nervous system) might generate symptoms. This Review highlights the crosstalk between the gut microbiota, the enteroendocrine system, the immune system and the role of intestinal permeability in patients with IBS.
Little is known about the population prevalence or demographic distributions of Rome IV functional bowel disorders (FBDs) or their effects on quality of life. We examined these in a multinational ...survey.
We analyzed data from a population-based survey of adults in the United States, Canada, and United Kingdom (5931 valid responders; 49.2% female; mean age, 47.4 years; range, 18–92 years). The survey included the Rome IV Diagnostic Questionnaire, Rome III irritable bowel syndrome (IBS) and constipation questions, and the SF-8 quality of life questionnaire.
The prevalence values of census-adjusted Rome IV FBDs were similar among the 3 countries; ranges were: 4.4%–4.8% for IBS, 7.9%–8.6% for functional constipation, 3.6%–5.3% for functional diarrhea, 2.0%–3.9% for functional bloating or distention, 1.1%–1.9% for opioid-induced constipation, 7.5%–10.0% for unspecified FBDs, and 28.6%–31.7% for any Rome IV FBD. FBDs were less common in older individuals, and all except functional diarrhea were more common in women. IBS was only half as prevalent by Rome IV as by Rome III criteria (4.6% vs 9.0% overall), primarily due to higher Rome IV minimum pain frequency. Functional diarrhea and functional constipation were more prevalent by Rome IV than Rome III criteria. Subjects with FBD had significant reductions in quality of life and reported more gastrointestinal doctor consultations than other subjects.
More than 1 in 4 adults in the general population meet the Rome IV criteria for FBDs. These disorders affect quality of life and increase use of gastrointestinal health care. The switch from Rome III to Rome IV criteria reduces the prevalence of IBS by half, but increases the prevalence of functional constipation and functional diarrhea.
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The diagnostic criteria for irritable bowel syndrome (IBS) have recently been updated from Rome III to Rome IV. Whereas in Rome III a diagnosis of IBS entailed chronic abdominal pain or discomfort at ...least 3 days per month, in Rome IV the term discomfort has been removed and the frequency of abdominal pain increased to at least 1 day per week. We examined how this change in IBS criteria impacts on clinical characteristics and pathophysiological factors.
A total of 542 Swedish subjects with Rome III IBS completed a baseline questionnaire enquiring for the number of abdominal pain days in the last 10 days; this was subsequently used as a surrogate marker to identify Rome IV IBS, in that (a) those with 0 or 1 day of pain were classed as Rome IV-negative, and (b) those with ≥2 days of pain were classed as Rome IV-positive. Comparisons were made between Rome IV-positive and -negative IBS groups for demographics, IBS subtype, gastrointestinal and psychological symptoms, somatisation, fatigue, disease-specific quality of life, rectal sensitivity, and oro-anal transit time.
Overall, 85% of Rome III IBS patients fulfilled the Rome IV criteria for IBS, but 15% did not. Rome IV-positive subjects were significantly more likely to be female, have poorer quality of life, greater pain severity, bloating, somatisation, fatigue, and rectal sensitivity than Rome IV-negative subjects. There were no differences in severity of anxiety or depression, IBS subtypes, bowel habit dissatisfaction, or oro-anal transit time. Finally, increasing number of pain days correlated positively with symptoms and visceral hypersensitivity.
Most Rome III-positive IBS patients seeking healthcare fulfil the Rome IV IBS criteria. They constitute a more severe group than those who lose their IBS diagnosis.
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