The fact that gut microbiota directly affects chronic pain such as fibromyalgia has been proven for the first time. It has been confirmed that pain disappears when gut microbiota from healthy individuals is transplanted. The scientific community has assessed this research as presenting a new avenue for treating chronic pain, for which there has been no suitable medication. The research team is currently conducting large-scale clinical trials to apply this to actual patients.
A joint research team from the Technion-Israel Institute of Technology and McGill University in Canada published in the international journal Neuron on the 24th (local time) that "gut microbiota affects the regulation of chronic pain, which was confirmed through animal experiments and clinical trials involving humans."
Fibromyalgia is known to be a refractory chronic disease experienced by about 2% to 4% of the global population. It causes pain and fatigue throughout the body without any muscle or nerve damage, and particularly a high percentage of patients are women. To date, clear causes or treatments have not emerged.
The research team found in 2019 that the gut microbiota composition of fibromyalgia patients was significantly different from that of healthy individuals. They reported that these microbiota differences could be the cause of pain and conducted animal experiments.
The research team first transplanted gut microbiota obtained from the feces of fibromyalgia patients and healthy women into mice that had their gut microbiota eliminated by antibiotics. Mice transplanted with patients' microbiota showed hypersensitivity and pain responses to pressure and thermal and cooling stimuli. In contrast, mice that received microbiota from healthy individuals did not exhibit such responses.
Subsequently, antibiotics were applied to the mice that showed pain responses, removing the existing microbiota, and when gut microbiota from healthy individuals were transplanted, the pain responses significantly decreased. The research team speculated that the gut microbiota of fibromyalgia patients stimulates the immune system or produces metabolites that affect the neural circuits controlling pain signals.
Following the animal experiments, tests were also conducted on actual patients. Fourteen fibromyalgia patients who did not respond to existing treatments were given gut microbiota extracted from healthy individuals in pill form for 10 weeks. Participants, like the mice, first removed their existing gut microbiota using antibiotics.
Of the 14 participants, 12 showed improvement not only in pain but also in sleep disturbances and anxiety symptoms. Overall, pain sensitivity significantly decreased. Amir Minerbi, a professor at the Technion-Israel Institute of Technology, who led the research, explained that "the gut microbiota of fibromyalgia patients can stimulate neural circuits involved in pain, or convert chemical substances released from the liver into pain-inducing molecules." This implies that the gut environment may be a key factor in determining pain sensitivity.
The scientific community is hopeful that gut microbiota could serve as a new treatment for chronic pain patients. Previous studies have found that gut microbiota not only affects digestive function but also impacts the health of various organs, including the brain. Gut bacteria are known to help prevent digestive diseases as well as arthritis, obesity, gastritis, and brain diseases.
Katelyn Sadler, a professor of neurology at the University of Texas, noted, "This study showed that gut microbiota is one of the causes of fibromyalgia and that this result could lead to non-opioid-based treatments for chronic pain patients." However, she stated that "large-scale clinical trials are necessary to clarify whether the factors causing changes in microbiota in fibromyalgia are genetic or environmental."
The research team is conducting large-scale clinical trials involving 80 participants as follow-up research. They believe that discovering the bacteria causing fibromyalgia-related pain through future clinical trials will help develop treatments.
References
Neuron (2025), DOI: https://doi.org/10.1016/j.neuron.2025.03.032