Gut Microbiota and IBS

There are trillions of microorganisms that live in our intestines. Formerly called the gut flora, these bacteria are known as the gut microbiota. Approximately one-third of the gut microbiota is common among people, but two-thirds are specific to the individual. Gut microbiota is also known as “good bacteria.” These organisms are helpful, providing assistance in digestion, boosting immunity, and helping maintain the integrity of the intestinal lining. While the exact cause of IBS is not known, one of the contributing factors may be an imbalance in the gut microbiota, such as an overgrowth of certain kinds of bacteria.¹

Changes to Microbiota May Cause IBS

A recent review of published research by a team at the Mayo Clinic suggests that changes to the microbiota in the intestines may be a cause of IBS. They found that diet and antibiotic use can change the makeup of bacteria in the gut, potentially contributing to symptoms experienced by people with IBS. In addition, researchers cited data that suggests that emotional stress can impact the shape and function of microorganisms in the gut.²

When the composition of the gut microbiota is changed, it can have multiple effects on the body. Researchers found that changing the gut microbiota may influence the ability of the intestines to contract and move waste through the system, which may cause symptoms like constipation or bloating. Changes in the gut microbiota can also impair communication between the immune, nervous, and endocrine systems, which can increase a person’s risk of developing IBS. These findings are significant, as they may help researchers develop effective therapies for IBS targeting microbiota.²

Specific Gut Microbiota “Signature” Linked to IBS

Another recent study found that a specific combination of microbiota is linked to IBS severity. Researchers obtained fecal and mucosal samples from adults with IBS as well as healthy adults. Analyzing the samples, they found that patients with severe IBS had a different microbiota signature than patients with mild to moderate IBS or the healthy controls. The severe IBS microbiota signature was negatively associated with characteristics such as microbial richness and exhaled methane. This means that people with severe IBS were less likely to have a wide variety of different microbes and less likely to have methane show up on a breath test. Researchers in this study found that diet and medications didn’t significantly influence the microbiota signature.³

Assessing Your Gut Microbiota

One of the tools frequently used to test the bacteria in the gut is a breath test. Breath tests can measure gases such as hydrogen and methane, which are produced by bacteria. A baseline breath sample is collected from the patient, and then the patient is given a drink with either lactose or glucose. The breath is again measured at several intervals. If the test results come back positive for these gases, your doctor may recommend a course of antibiotics, such as Xifaxan (rifaximin).

Probiotics are over-the-counter supplements containing beneficial bacteria and are used by many people with IBS to support the gut microbiota. The most well-studied probiotic is Bifidobacteria infantis, which has been proven to reduce the abdominal symptoms of IBS, particularly bloating and bowel function. Other studies have looked at strains of the Lactobacillus and Propionibacterium species.⁴