People with chronic fatigue syndrome may have imbalances in their gut bacteria, a new study suggests. The study found that people with chronic fatigue syndrome had higher levels of certain gut bacteria and lower levels of others compared to healthy people who didn’t have the condition. The researchers then checked to see if these imbalances also characterized the subset of patients in the study who had irritable bowel syndrome (IBS), an intestinal disorder that is common in people with chronic fatigue syndrome. Results showed that patients did indeed have different patterns of gut bacteria disturbances depending on whether they had only chronic fatigue syndrome or both chronic fatigue syndrome and IBS.

The findings suggest that researchers may be able to divide chronic fatigue syndrome patients into different groups depending on their gut bacteria imbalances, which could aid in the diagnosis and treatment of the disease, the researchers said. Chronic fatigue syndrome is a disorder in which people have extreme fatigue that is not improved by rest and is not the result of another medical condition. An estimated 35 percent to 90 percent of patients with chronic fatigue syndrome also report abdominal discomfort consistent with symptoms of IBS, the researchers said. The reason for the link between chronic fatigue syndrome and IBS is not clear; chronic fatigue syndrome may predispose patents to developing IBS, or the two conditions might share underlying causes, the researchers said. Previous studies have already found district differences in gut bacteria in chronic fatigue syndrome patients compared to healthy people. But the new study is one of the first to look for differences between gut bacteria in chronic fatigue syndrome patients who have IBS and bacteria in those who do not have IBS. Some researchers have hypothesized that altered gut bacteria may play a role in the causing chronic fatigue syndrome, because some research shows that a person’s gut bacteria may affect their central nervous system and immune system. However, it’s also possible that changes in gut bacteria are a consequence of having chronic fatigue syndrome.