IRRITABLE BOWEL SYNDROME (IBS)

Post Infectious IBS: Road to Cure – Dr. Mark Pimental

Dr. Mark Pimentel explained that IBS is now understood as a real, physical illness—often starting after food poisoning—rather than something “in the mind.” Certain bacteria from contaminated food make a toxin that can trigger the immune system to mistakenly attack nerves in the gut. This damage stops the gut’s natural “cleaning waves,” leading to a buildup of bacteria in the small intestine (SIBO). Around 60% of IBS cases are linked to this process. There are three main SIBO types—hydrogen, hydrogen sulfide, and methane—which cause different symptoms like diarrhea or constipation and need different treatments. New blood tests can confirm post-infectious IBS, proving it’s a true disease and helping doctors create more targeted treatments.

Irritable Bowel Syndrome and the Gut Microbiome: A Comprehensive Review (J Clin Med, 2022)
This is a broad, up-to-date review that pulls together human and animal studies to show how alterations in the gut microbiome are a consistent feature of many people with IBS. The authors review evidence linking microbial shifts to hallmark IBS mechanisms — changes in motility, visceral hypersensitivity, low-grade immune activation, altered fermentation and gas production, and changes to the gut–brain axis. They also summarize clinical approaches that target the microbiome (low-FODMAP diet, rifaximin, specific probiotics, and FMT), noting the strongest evidence is for dietary manipulation and rifaximin in selected subgroups. Importantly, the review emphasizes heterogeneity: not all IBS patients show the same microbial patterns, and study methods differ widely, so translating microbiome findings to routine care still needs standardized tests and better predictive markers.

Is Irritable Bowel Syndrome a Diagnosis of Exclusion?: A Survey of Primary Care Providers, Gastroenterologists, and IBS Experts

This study found that while IBS should be diagnosed based on symptoms (using tools like the Rome criteria), most general healthcare providers still treat it as a diagnosis of exclusion—meaning they only diagnose IBS after ruling out other conditions. In contrast, IBS specialists are more likely to make a direct diagnosis based on symptoms alone, order fewer tests, and spend less on investigations. The findings highlight a gap between expert guidelines and everyday practice, suggesting the need for better education and guideline use among non-specialists.

Predicting Response to Rifaximin in Irritable Bowel Syndrome with Diarrhea: Is the Answer Blowing in the Wind?

This study found that a simple breath test (called lactulose breath test) can help predict if people with IBS and diarrhea will feel better after taking the antibiotic rifaximin. People with a positive breath test were more likely to improve, but the chance of symptoms coming back later was similar for everyone. This means the test can help decide who might benefit most from the treatment.

The cognitive behavioural model of irritable bowel syndrome: a prospective investigation of patients with gastroenteritis

Researchers followed over 600 people who had gastroenteritis (a stomach infection) but no history of IBS. At the time of the infection, they measured things like stress, anxiety, how people thought about illness, and how they behaved (for example, whether they rested or pushed through symptoms). They checked back 3 and 6 months later to see who developed IBS. They found that higher stress, anxiety, somatisation (experiencing lots of physical symptoms), negative beliefs about illness, and a tendency to “push through” the illness rather than rest, were linked to developing IBS afterward. Depression and perfectionism were not linked.

Increasing Evidence That Irritable Bowel Syndrome and Functional Gastrointestinal Disorders Have a Microbial Pathogenesis

This is a review that looks at studies suggesting our gut microbes (the microbiota) play an important part in conditions like irritable bowel syndrome (IBS) and other functional gut issues (like functional constipation or diarrhoea). The authors argue that things like imbalances in gut microbes, mild immune activation, leaky gut lining, and changes in gut movement can combine with diet and other environmental factors to cause symptoms. They also emphasize that many prior studies have found inconsistent results, so while the evidence is growing, there’s still a lot left to understand about how exactly microbes contribute to these disorders.

Immune responses in the irritable bowel syndromes: time to consider the small intestine

This review discusses how the immune system in the small intestine might play a role in irritable bowel syndrome (IBS). The authors suggest that while much research has focused on the large intestine, the small intestine's immune responses could also contribute to IBS symptoms. They highlight the need for more studies to understand this aspect and consider it in future IBS research and treatment strategies.

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy

This review explores the connection between small intestinal bacterial overgrowth (SIBO) and irritable bowel syndrome (IBS). The authors discuss how SIBO may contribute to IBS symptoms and suggest that the presence of SIBO in IBS patients could indicate an underlying organic cause, challenging the traditional view of IBS as purely functional. They advocate for considering SIBO in the diagnosis and treatment of IBS to improve patient outcomes.

Assessment of Anti-vinculin and Anti-cytolethal Distending Toxin B Antibodies in Subtypes of Irritable Bowel Syndrome

This study aimed to identify specific antibodies that could help distinguish between different subtypes of irritable bowel syndrome (IBS). The researchers focused on two antibodies: anti-vinculin and anti-cytolethal distending toxin B (CdtB). They found that these antibodies were present in certain IBS subtypes, suggesting that they might play a role in the development of the condition. The study concludes that these antibodies could potentially serve as biomarkers for identifying specific IBS subtypes, which may lead to more targeted treatments in the future.

Hydrogen sulphide in exhaled breath: a potential biomarker for small intestinal bacterial overgrowth in IBS

This study found that individuals with diarrhoea-predominant IBS exhibited distinct alterations in exhaled breath H₂S levels, depending on the presence or absence of SIBO. The analysis of H₂S excretion kinetics revealed a correlation between breath H₂S levels and SIBO, even in cases where traditional hydrogen breath tests failed to diagnose SIBO. Furthermore, breath H₂S levels were able to track the progression of SIBO, including after the eradication of bacterial overgrowth. These findings suggest that measuring H₂S in exhaled breath could serve as a non-invasive, rapid, and precise method for assessing SIBO in IBS patients, offering a potential alternative to endoscopy-based microbial cultures.

Functional dysbiosis within the gut microbiota of patients with constipated-irritable bowel syndrome

This study found that patients with IBS-C exhibited significant alterations in their gut microbiota compared to healthy controls. Specifically, there was a decrease in the diversity of microbial species, with a notable reduction in beneficial bacteria such as Bifidobacterium and Lactobacillus. Additionally, an increase in potentially harmful bacteria was observed. These findings suggest that dysbiosis, or an imbalance in the gut microbiota, may play a role in the pathophysiology of IBS-C. The study highlights the potential for microbiota-targeted therapies in managing IBS-C symptoms.

Kiwifruit improves bowel function in patients with irritable bowel syndrome with constipation

This study found that daily intake of kiwifruit led to significant improvements in bowel function among IBS-C patients. Participants who consumed kiwifruit experienced increased frequency of bowel movements, improved stool consistency, and reduced abdominal discomfort. The researchers suggest that the high fibre content and unique combination of nutrients in kiwifruit may contribute to these beneficial effects.

Circulating Anti-cytolethal Distending Toxin B and Anti-vinculin Antibodies as Biomarkers in Community and Healthcare Populations With Functional Dyspepsia and Irritable Bowel Syndrome

The article explains new advances in diagnosing a type of irritable bowel syndrome called IBS with diarrhea (IBS-D). Scientists have found special markers in the blood, called biomarkers, that help doctors tell IBS-D apart from other similar gut problems more accurately. These biomarkers can improve diagnosis so patients get the right treatment faster, making managing IBS-D easier and more effective.