By Pat Anson, PNN Editor

Over the years there’s been a lot of speculation about what causes fibromyalgia – everything from gluten and genetics to childhood trauma, spinal fractures and a weakened immune system.

About 5 million Americans suffer from fibromyalgia, a poorly understood disorder characterized by deep tissue pain, fatigue, mood swings and insomnia. It can take years for a patient to be diagnosed and treatments are often ineffective – in part because of uncertainty about what actually causes fibromyalgia.

For the first time, researchers at McGill University Health Centre in Montreal have found an association between gut bacteria and fibromyalgia. It’s not clear whether the microbes cause fibromyalgia or if they are a symptom, but the discovery opens the door to new forms of treatment and diagnosis. The findings are being reported in the journal Pain.

"We found that fibromyalgia and the symptoms of fibromyalgia — pain, fatigue and cognitive difficulties — contribute more than any of the other factors to the variations we see in the microbiomes of those with the disease,” said lead author Amir Minerbi, MD, of the Alan Edwards Pain Management Unit at McGill University Health Centre. 

“We also saw that the severity of a patient's symptoms was directly correlated with an increased presence or a more pronounced absence of certain bacteria - something which has never been reported before."

Minerbi and his colleagues enrolled 156 women in their study – about half had fibromyalgia and the rest were a healthy control group. Participants were interviewed and gave stool, blood, saliva and urine samples, which were then compared.

Researchers found that the two groups had strikingly different types and amounts of gut bacteria. Nineteen different species of bacteria were found in either greater or lesser quantities in the gut microbiomes of fibromyalgia patients than in the healthy control group.

For example, Faecalibacterium prausnitzii, one of the most abundant and well-studied bacteria in the human gut, was found to be depleted in fibromyalgia patients. It is believed to block pain and inflammation in the intestines.

Other bacteria associated with irritable bowel syndrome, chronic fatigue syndrome and interstitial cystitis were found to be abundant in the fibromyalgia patients, but not in the healthy control group.  

The bacterial differences don’t appear to be related to diets, lifestyles or genetics, since some of the healthy participants lived in the same house as the fibromyalgia patients or were their parents, offspring or siblings.

"We used a range of techniques, including Artificial Intelligence, to confirm that the changes we saw in the microbiomes of fibromyalgia patients were not caused by factors such as diet, medication, physical activity, age, and so on, which are known to affect the microbiome," says Minerbi.

Researchers say it's not clear whether the changes in gut bacteria seen in fibromyalgia patients are simply markers of the disease or whether they play a role in causing it. Because fibromyalgia involves a cluster of symptoms, the next step will be to investigate whether there are similar changes in the gut microbiome of patients with other types of chronic pain, such as back pain, headaches and neuropathic pain.

“This is the first evidence, at least in humans, that the microbiome could have an effect on diffuse pain, and we really need new ways to look at chronic pain." said senior author Yoram Shir, MD, Director of the Alan Edwards Pain Management Unit

If their findings are confirmed, researchers think their discovery could speed up the process of diagnosing fibromyalgia.

"By using machine learning, our computer was able to make a diagnosis of fibromyalgia, based only on the composition of the microbiome, with an accuracy of 87 per cent. As we build on this first discovery with more research, we hope to improve upon this accuracy, potentially creating a step-change in diagnosis," says Emmanuel Gonzalez, PhD, Canadian Center for Computational Genomics and the Department of Human Genetics at McGill University.

Several previous studies have suggested an association between diet and fibromyalgia. Donna Gregory Burch says her fibromyalgia symptoms improved when she went on a gluten-free diet. Studies show that consuming food additives such as monosodium glutamate (MSG) can worsen symptoms, while foods rich in Vitamin D can help reduce joint and muscle pain.