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Introduction:
Irritable bowel syndrome (IBS) is a common gastrointestinal disease, causing stomach pain or discomfort combined with abnormal bowel patterns. The condition affects around ten to 25 percent of the population in the United States, reducing their quality of life. IBS symptoms are 1.5 to two times more common in women than males. Furthermore, women are more likely to experience abdominal pain and constipation, whereas males report diarrhea. IBS has been linked to increased stress, lower quality of life, and decreased productivity at work. The exact cause of the disease is unknown, but it involves disruption in brain-gut communication (brain-gut axis). This disruption can lead to abnormal intestinal movements, permeability, and gut microbiota alteration. The gut microbiota is believed to play an essential role in developing IBS. This article briefly explains how gut microbiota (gut bacteria) causes IBS and what factors affect the gut microbiome.
What Is Irritable Bowel Syndrome (IBS)?
Irritable bowel syndrome (IBS) is defined as a condition characterized by a set of symptoms that include abdominal pain and changes in bowel habits such as constipation, diarrhea, or both. IBS is a functional gastrointestinal disorder, a disorder of brain-gut interaction. The gut-brain axis is a complex communication system that connects the gut and brain. The brain interacts with the gut through nerves, hormones, the immune system, and gut bacteria. Abnormality in how the brain and gut communicate and coordinate their functions can lead to health problems in the gut (irritable bowel syndrome) and the brain. Due to this, the gut becomes hypersensitive and causes discomfort like bloating and pain in the abdomen. It can also cause changes in muscle contraction and relaxation in the bowel, leading to constipation, diarrhea, or both.
What Is the Role of the Gut Microbiome In IBS?
The human gut microbiome comprises diverse beneficial microbes, including bacteria, viruses, fungi, and protozoa. These microbes play an important role in dietary nutrient metabolism, maintaining gut barrier integrity, regulating the immune system, and protecting against pathogens. Alteration in the gut microbiome is known as microbiota dysbiosis. This can occur due to loss or overgrowth of specific bacteria, overall diversity, or mutation. Studies indicate that gut dysbiosis may cause IBS. Normal gut bacteria play an important role by producing helpful molecules that maintain the gut's health and support the immune system. Slight disruptions in gut bacteria balance can lead to inflammatory changes in the gut, which increase oxidative stress and cause increased intestinal permeability (leaky gut).
What Are the Factors That Influence Gut Microbiome?
Several factors influence the composition and diversity of gut microbiome are as follows:
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Age: The gut microbiome changes with age. As people age, their overall microbial diversity declines, leading to age-related gut dysbiosis.
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Sex: Some studies suggest that gender plays a role in gut microbiota diversity. Women are diagnosed with IBS more frequently than men. This suggests that sex might play a role in IBS by influencing gut bacteria diversity.
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Ethnicity: Ethnic background influences gut microbiome composition due to genetic, dietary, and lifestyle factors.
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Diet: Short- and long-term dietary choices substantially impact the gut flora. Diets high in fiber from plant sources promote beneficial bacteria such as Bifidobacterium and Lactobacillus, but diets high in fats or animal proteins can harm microbiome composition. A diet low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) is typically used as the first line of treatment for IBS symptoms.
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Pre- and Postnatal Factors: Microbial colonization begins before birth and continues after delivery. A healthy microbiome is important for the proper development of the brain-gut axis. Studies reveal that infant gut microbiome is influenced by factors such as the mother's diet during pregnancy, delivery type (vaginal vs. C-section), and duration of breastfeeding.
What Are Microbiome-Based Treatments for IBS?
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Prebiotics: Prebiotics are nondigestible carbohydrates, fructooligosaccharides (FOS] and galactooligosaccharides (GOS) that encourage the growth of bacteria and provide health benefits to the host. Their anti-inflammatory and antioxidant effects are also beneficial for IBS symptoms.
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Probiotics: Probiotics are live or attenuated bacteria that improve gut health. Probiotics may help individuals with IBS by reducing gut sensitivity and fighting inflammation. Studies have also shown that taking probiotics improves IBS symptoms.
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Antibiotics: Antibiotics have been considered a potential treatment for IBS due to evidence that microbiota dysbiosis (an imbalance in gut bacteria) is linked to IBS. Rifaximin is an antibiotic that is frequently used to treat IBS. It is unclear exactly how antibiotics reduce the symptoms of irritable bowel syndrome. Antibiotics may change the gut's microbial composition, lowering the amount of dangerous bacterial products and changing immunological and inflammatory responses.
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Dietary Changes: Many individuals with IBS associate certain foods with worsening symptoms. Foods like wheat products, onions, fruits, vegetables, sorbitol, and certain dairy are poorly absorbed and contain highly fermentable carbohydrates, known as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). FODMAPs increase fluid and gas in the intestines, leading to IBS symptoms. A diet low in FODMAPs (specific types of carbohydrates) is often recommended for IBS management.
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Fecal Microbiota Transplantation (FMT): FMT is a procedure that involves transplanting stool from a healthy person into someone's gut to modify their gut bacteria. It is used to treat Clostridium difficile infection and is currently being investigated as a treatment for IBS and other gastrointestinal problems.
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Antidepressants: According to research, certain antidepressants, such as tricyclics and selective serotonin reuptake inhibitors, can alleviate general IBS symptoms. It is unclear how antidepressants reduce IBS symptoms. It has been reported that people with IBS and depression might have different gut bacteria compared to healthy people.
Conclusion:
The gut microbiota or gut bacteria and disturbances in the brain-gut axis may have a role in causing irritable bowel syndrome (IBS). Although previous studies have linked IBS to change gut flora, it is unclear exactly how the gut microbiome contributes to developing IBS. Furthermore, treatments like prebiotics, probiotics, and fecal microbiota transplant targeting microbiome in IBS patients have yet to show any long-lasting improvements with these methods. To fully comprehend the connection, more investigation is required.
