The role of diet in the pathophysiology and management of irritable bowel syndrome

The Relevance of Food Constituents to the Irritable Bowel Syndrome: A Rome IV-Based Prevalence Study Among Medical Students

BACKGROUND/AIMS

Irritable bowel syndrome is prevalent in the general population. This study investigates the association between dietary intake and irritable bowel syndrome in medical college students at King Saud University besides its prevalence.

MATERIALS AND METHODS

This is an analytical cross-sectional study of 426 students (271 males and 155 females, age 21.21 ± 1.58 years) from 5 academic levels of King Saud University Medical College. A self-reported questionnaire for Rome IV criteria was completed by each participant. They also filled out a food frequency questionnaire to assess their nutritional intake.

RESULTS

The overall prevalence of irritable bowel syndrome was 17.8% without correlation to age and academic year in Medical School. However, the prevalence was higher in females than in males (40/115 vs. 36/235, P = .001). The irritable bowel syndrome group consumed significantly more energy, carbohydrates, and saturated fatty acids, while the non-irritable bowel syndrome group consumed significantly more fibers and niacin (P < .001 and P = .005, respectively).

CONCLUSION

About 17.8% of medical students had irritable bowel syndrome with a greater prevalence in females. The irritable bowel syndrome group consumed significantly more energy, carbohydrates, and saturated fatty acids, while the non-irritable bowel syndrome group consumed significantly more fibers and niacin. Our results did not show any significant association between irritable bowel syndrome and fermentable oligosaccharide, disaccharide, monosaccharide, and polyol intake. Overall, both groups were not adhering to the Saudi dietary recommended intake.

Involvement of enteric glial cells in colonic motility in a rat model of irritable bowel syndrome with predominant diarrhea

The enteric nervous system (ENS) is one of the important systems that regulate gastrointestinal function. The ENS is made up of enteric glial cells (EGCs) and neurons. For a long time, it was believed that the function of EGCs was only to give structural support to neurons. However, recent evidence indicates EGCs are involved in most gut functions, including the development and plasticity of the ENS, epithelial barrier, and motility. However, it remains unclear whether EGCs have the potential to modify colonic motility following irritable bowel syndrome (IBS) with predominant diarrhea (IBS-D). This study aimed to investigate changes in EGCs during IBS-D and assessed the effects of manipulating EGCs. An IBS-D rat model was constructed using acetic acid and restraint stress, and DL-fluorocitric acid (FC), an inhibitor of EGCs, was administered. The changes in EGCs and colonic motility were studied by employing techniques comprising morphological, molecular biological and functional experiments. The results showed significant activation of EGCs in the myenteric plexus (MP) of the IBS-D-induced rat colon with accelerated colonic motility. FC significantly reduced the activation of EGCs and colonic motility caused by acetic acid and restraint stress. Hypercontraction of the colon caused by IBS-D may be associated with activation of EGCs in the MP of the colon and this was prevented by FC. Therefore, regulating colon hypercontraction through interference with the activation of EGCs has significant prospects for clinical application to alleviate diarrhea in patients with IBS-D.

Gut microbiota plays a role in irritable bowel syndrome by regulating 5-HT metabolism

Irritable bowel syndrome (IBS) is a common chronic functional gastrointestinal disorder. Brain-gut-microbiota axis dysfunction is an important pathogenic factor for IBS, in which neurotransmitters and gut microbes play key roles. The gastrointestinal tract contains large amounts of serotonin (5-hydroxytryptamine, 5-HT), a neurotransmitter that has been strongly linked to IBS-related symptoms. More than 90% of serotonin is synthesized in the gut by enterochromaffin cells (ECs), and certain intestinal flora can affect the occurrence and development of IBS by regulating 5-HT and its metabolism. In this review, we will discuss the role of gut microbiota in IBS by regulating 5-HT.

Irritable bowel syndrome patients who are not likely to respond to fecal microbiota transplantation

BACKGROUND

Fecal microbiota transplantation (FMT) interventions have recently been advocated to not succeed in every irritable bowel syndrome (IBS) patient, since the outcome of FMT varies with the IBS subset. This study investigated the factors potentially affecting FMT response using the same patient cohort used in our previous study.

METHODS

This study included 109 patients who received allogenic FMT. Patients completed five questionnaires that assessed their symptoms and quality of life at baseline and at 2 weeks, 1 month, and 3 months after FMT. Patients also provided fecal samples at baseline and 1 month after FMT. The fecal bacterial profile and dysbiosis index (DI) were determined using 16S rRNA gene PCR DNA amplification covering variable genes V3-V9. Response to FMT was defined as a decrease of ≥50 points in the total IBS-SSS score after FMT.

RESULTS

An IBS patient's response or nonresponse to FMT was not determined by age, IBS duration, IBS subtype, IBS symptoms, fatigue, quality of life, or DI. There were more male nonresponders than responders, and the fluorescence signals of Alistipes were lower in nonresponders than in responders.

CONCLUSIONS

We concluded that IBS patients who are male and/or have low fecal Alistipes levels are most likely to not respond to FMT treatment. Whether low fecal Alistipes levels could be used as a marker for predicting the outcome of FMT remains to be determined. www.

CLINICALTRIALS

gov (NCT03822299).

Association of Diet, Body Mass Index, and Lifestyle on the Gastrointestinal Health Risk in a Sample of Adults

Gastrointestinal functional disorders are characterized by abnormalities in motility with visceral hypersensitivity, representing a global public health problem. We aimed to determine whether eating habits, lifestyle characteristics, and body mass index (BMI) are associated with gastrointestinal health risk. The Gastrointestinal Health (GIH) test of the World Gastroenterology Organization (WGO) and the Roma IV criteria were applied. We obtained information on food consumption habits and aerobic exercise, among other variables. Not exercising regularly, drinking water and eating vegetables less than recommended, having high body weight, and taking symptomatic medication were variables that explained 73% of the probabilities of not having good GIH (R² = 0.734). According to Rome IV criteria, women had a 50% higher risk than men of having functional bowel disorder (RR 1.6, 95% CI: 1.04, 2.45). Among the men studied, eating few or no vegetables and drinking less than 1 L of water daily was more frequent; however, the women had significantly more intestinal symptoms. In addition, constipation was higher among women than men (p = 0.020). All of the above explains the prognostic value of eating habits and the importance of paying attention to body weight to reduce the risk of gastrointestinal disease.

Current Treatment Options and Therapeutic Insights for Gastrointestinal Dysmotility and Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGIDs) have been re-named as disorders of gut-brain interactions. These conditions are not only common in clinical practice, but also in the community. In reference to the Rome IV criteria, the most common FGIDs, include functional dyspepsia (FD) and irritable bowel syndrome (IBS). Additionally, there is substantial overlap of these disorders and other specific gastrointestinal motility disorders, such as gastroparesis. These disorders are heterogeneous and are intertwined with several proposed pathophysiological mechanisms, such as altered gut motility, intestinal barrier dysfunction, gut immune dysfunction, visceral hypersensitivity, altered GI secretion, presence and degree of bile acid malabsorption, microbial dysbiosis, and alterations to the gut-brain axis. The treatment options currently available include lifestyle modifications, dietary and gut microbiota manipulation interventions including fecal microbiota transplantation, prokinetics, antispasmodics, laxatives, and centrally and peripherally acting neuromodulators. However, treatment that targets the pathophysiological mechanisms underlying the symptoms are scanty. Pharmacological agents that are developed based on the cellular and molecular mechanisms underlying pathologies of these disorders might provide the best avenue for future pharmaceutical development. The currently available therapies lack long-term effectiveness and safety for their use to treat motility disorders and FGIDs. Furthermore, the fundamental challenges in treating these disorders should be defined; for instance, 1. Cause and effect cannot be disentangled between symptoms and pathophysiological mechanisms due to current therapies that entail the off-label use of medications to treat symptoms. 2. Despite the knowledge that the microbiota in our gut plays an essential part in maintaining gut health, their exact functions in gut homeostasis are still unclear. What constitutes a healthy microbiome and further, the precise definition of gut microbial dysbiosis is lacking. More comprehensive, large-scale, and longitudinal studies utilizing multi-omics data are needed to dissect the exact contribution of gut microbial alterations in disease pathogenesis. Accordingly, we review the current treatment options, clinical insight on pathophysiology, therapeutic modalities, current challenges, and therapeutic clues for the clinical care and management of functional dyspepsia, gastroparesis, irritable bowel syndrome, functional constipation, and functional diarrhea.