What's causing your IBS
Irritable bowel syndrome (IBS) can feel like a mystery, but experts have uncovered some clues about what might be causing the discomfort and how to better manage it. For some, IBS symptoms stem from muscle spasms in the colon, while others experience heightened sensitivity in the nerves of their digestive system, making everyday discomfort feel much worse. Though the exact cause isn't clear, factors like stress, antibiotics, and even bacterial overgrowth are thought to play a role.
Psychological factors. The brain and gut are intimately connected. Your thoughts and emotions can trigger symptoms in the gut, and the health of your gut can shape your mental well-being. Stress can cause more contractions in the intestines and increase sensitivity. It's not clear whether stress or other psychological factors may be a cause of IBS or vice versa. However, we do know that people with IBS often have higher levels of stress and anxiety and that this distress also can make IBS symptoms worse. People with IBS tend to have more symptoms of depression and anxiety compared with those who don't have the disorder. IBS also is more common among people who experienced psychological trauma as children.
Antibiotics. The human digestive tract contains trillions of bacteria, viruses, and fungi known collectively as the gut microbiota or gut flora. These microorganisms play several critical roles in our health, including digestion and immune system function. When we take antibiotics to combat bacterial infections, the drugs also kill helpful bacteria in the gut. Repeated treatments or long-term use of antibiotics may alter the gut flora in a way that disrupts the colon's normal function. Some animal and human research suggests that this disruption may lead to IBS in some cases. However, studies have not had consistent results, so more research is needed.
Bacterial overgrowth. Some people with IBS also have a surplus of bacteria in the small intestines, a condition called small intestinal bacterial overgrowth (SIBO). In this situation, people often have symptoms typical of IBS such as bloating, constipation, abdominal pain, and diarrhea.
It's unclear whether SIBO can be a cause of IBS, but people with IBS are more likely than others to test positive for SIBO. In addition, some research has found that IBS symptoms often decrease after antibiotic treatment that focuses on bacteria in the small intestine.
Estimates vary about how many people diagnosed with IBS also have SIBO, but research suggests it may be as high as 20%. Most studies diagnose SIBO with a breath test that measures gases released by the body's breakdown of sugars such as glucose and lactulose. There is a debate, however, about the reliability of the test results.
To learn more about IBS, read Iritable Bowel Syndrome, a Special Health Report from Harvard Medical School.
Image: © sumnersgraphicsinc/Getty Images
Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.