Fibromyalgia and Gut Microbiome Abnormalities

Bacteria levels correlate with symptom severity

Fibromyalgia has been linked to an abnormal gut microbiome for the first time, according to research out of Canada that was published in the prestigious journal Pain. Researchers believe this could lead to a diagnostic test and, depending on the findings of future research, could eventually lead to better treatments.

The study found significant differences in 19 species of gut bacteria in women with fibromyalgia and abnormal blood levels of two substances released by some of those bacteria. Researchers say the more abnormal the microbiome was, the more severe the fibromyalgia symptoms were. Additionally, the microbiome abnormalities could be used to predict the presence of fibromyalgia among study subjects.

Microbiome in the gut
Marcin Klapczynski / iStock / Getty Images

Fibromyalgia causes not only widespread pain, but fatigue, cognitive dysfunction, and potentially dozens of other symptoms. Currently, it takes many people five years to receive a diagnosis and research suggests that the potential for misdiagnosis is high. Current treatments are inadequate for many people, as well.

What Is the Gut Microbiome?

The gut microbiome is the total picture of microorganisms that live in your gastrointestinal tract (GIT). It’s sometimes referred to as gut microbiota or gut flora.

These microorganisms include:

  • Bacteria
  • Viruses
  • Protozoa
  • Fungi

While you may associate those things with illness, they’re also important for your health. Having the right ones, in the right balance, allows your digestive system to function properly. When things are out of balance, it can lead to all kinds of symptoms—digestive and, research is showing, beyond.

The Brain-Gut Axis

A relatively new area of interest for researchers is the brain-gut axis. This axis is made up of a complex set of signals that go from your gut flora to your:

Research has linked dysfunction in every one of those systems to fibromyalgia, which is sometimes called a neuro-endocrine-immune disorder or a “stress-related” condition.

Prior studies have shown a role for altered gut microbiota in neurologic, psychiatric, metabolic, cardiovascular, and oncologic disorders. It’s because some of the same processes involved in psychiatric and neurologic conditions are also involved in chronic pain that the researchers set out to investigate a connection with fibromyalgia.

Adding to their interest are previous human studies showing altered gut microbiota in people with irritable bowel syndrome (IBS), chronic dysfunctional pelvic pain, rheumatoid arthritis, and a class of arthritis diseases called spondyloarthropathies.

The Gut Microbiome Study

The study included 77 women between 30 and 60 years old who had fibromyalgia and lived in Montreal, Canada. For comparison, researchers put together three control groups with a total of 79 participants. The groups were made up of:

  1. First-degree female relatives of the fibromyalgia participants (to control for genetics)
  2. Household members of the fibromyalgia participants (to help control for environmental factors)
  3. Unrelated women who were age-matched with the fibromyalgia group

The participants all filled out a dietary questionnaire for three days and the questionnaires were analyzed. Researchers say they found no significant differences between the groups when it came to vitamins and minerals in the diet as well as sugar, caffeine, alcohol, fiber, and fatty acids. They say the overall diet qualities weren’t significantly different between the groups, either.

Researchers then looked at the gut microbiome via stool samples. What they found was significantly different levels of 19 species of gut bacteria in the women with fibromyalgia. Some were at abnormally low levels while others were abnormally high.

One of the bacteria—Faecalibacterium prausnitzii—produces a fatty acid called butyrate that’s important for the well-being of the digestive tract. Earlier research has shown that several intestinal diseases involve butyrate depletion. In this study, it was found to be low in the fibromyalgia group.

The researchers note that Faecalibacterium prausnitzii depletion also is linked by other research to chronic fatigue syndrome, which is highly similar to fibromyalgia, is frequently comorbid with it, and is considered by some experts to be part of the same spectrum of illnesses. This bacterium is believed to lower pain and inflammation in the digestive tract as well as improving the function of the intestinal barrier. This study also found specific abnormalities in gut microbiota that have previously been linked to IBS and the painful bladder condition interstitial cystitis, both of which frequently overlap with fibromyalgia.

Anxiety, depression, and emotional stress have been associated with gut microbiota abnormalities in the general population, and these conditions all are common in people with fibromyalgia, as well.

However, some of the findings might be unique to fibromyalgia, which is one reason this work could lead to a new diagnostic test.

Two other bacterial species that were low in fibromyalgia—Bacteroides uniformis and Prevotella copri—have been found to be elevated in inflammatory arthritis and may be linked to both osteoarthritis and rheumatoid arthritis. This underscores the differences between fibromyalgia and arthritis, even though fibromyalgia was originally considered a rheumatologic condition.

The fibromyalgia group had low levels of two other products of bacteria: propionic acid and isobutyric acid.

Two bacterial species that were more abundant in the fibromyalgia group were Clostridium scindens and Bacteroides desmolans. Those species are both involved in how the body uses cortisol, a major stress hormone that’s involved in the HPA axis.

Abnormalities Linked to Severity

Researchers say that high levels of specific bacteria were linked to numerous measures of disease severity in the fibromyalgia group, including:

  • Pain intensity
  • Widespread pain index
  • Cognitive dysfunction
  • Fatigue

Meanwhile, the high bacteria levels showed no consistent relationship with the participants’ age, lifestyle, or physical activity. That suggests that they do have a relationship with symptoms.

Causation or Correlation?

A major question posed by this research is: Do the abnormal levels cause fibromyalgia or it’s symptoms, or are they somehow a result of the condition? It could be, for instance, that an as-yet-unknown underlying mechanism of the illness causes changes that result in the abnormal gut flora.

This study doesn’t answer that question, but it does provide the groundwork for future research to explore it. If it turns out that the bacteria do have a causal relationship, that could lead to better fibromyalgia treatments than we currently have, and possibly even a means of preventing or curing it. It’s far too early to say, however. It takes a lot more than one test to establish anything scientifically.

What might be closer on the horizon is the long-sought-after objective diagnostic test. Right now, fibromyalgia is diagnosed based on symptoms and either the number of tender points around the body, as measured by a doctor putting a small amount of pressure on certain places, or by two questionnaires that evaluate the number and severity of symptoms.

Research has shown both of these methods to be pretty accurate. However, even with these two methods, not all doctors are comfortable with or skilled at making a fibromyalgia diagnosis. If studies showing high misdiagnosis rates are correct, it proves that we need something better.

Additionally, the nature of the fibromyalgia diagnostic process invites skepticism, both in the medical community and the general population. Far too many legitimately sick people face questions from people in their lives, including members of their medical care team, about whether they really do have fibromyalgia, and sometimes whether they’re even sick at all. An objective test could go a long way toward giving the condition more credibility.

If the results of the Canadian study are borne out, and microbiome testing can identify fibromyalgia with an 88% accuracy rate, we could finally have that test.

Other questions that will need to be answered by future research include:

  • Whether the same abnormalities are found in fibromyalgia populations in other regions (since all participants in this study came from one area)
  • Whether the alterations in gut flora are consistent enough in people with fibromyalgia to be clinically significant
  • Whether the gut microbiome plays a role in other chronic pain conditions
  • Whether taking steps to normalize the gut bacteria helps reduce symptoms
  • Whether the findings could be used to identify people who are at risk for developing fibromyalgia and whether early treatment could be preventive

A Word From Verywell

While there’s still a long way to go in answering the above questions, this is a promising start to a line of research that could lead to a greater understanding of a perplexing condition as well as chronic pain in general.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Walitt B, Katz RS, Bergman MJ, Wolfe F. Three-quarters of persons in the US population reporting a clinical diagnosis of fibromyalgia do not satisfy fibromyalgia criteria: The 2012 National Health Interview Survey. PLoS One. 2016 Jun 9;11(6):e0157235. doi:10.1371/journal.pone.0157235

  2. Lynch SV, Pedersen O. The human intestinal microbiome in health and disease. N Engl J Med 2016;375:2369–79. doi:10.1056/NEJMra1600266

  3. Pozuelo M, Panda S, Santiago A, et al. Reduction of butyrate- and methane-producing microorganisms in patients with Irritable Bowel Syndrome. Sci Rep. 2015;5:12693. Published 2015 Aug 4. doi:10.1038/srep12693

Additional Reading

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.