By Pat Anson, PNN Editor

Regular exercise can benefit people in many different ways, helping us lose weight, reduce the risk of heart disease, and boosting overall health.  

But researchers at the University of Nottingham have found that exercise has an unexpected benefit for people with arthritis. Regular exercise increases levels of beneficial bacteria in their digestive tracts, which reduces pain and inflammation by increasing levels of endocannabinoids – cannabis-like substances naturally produced by the body.

The study, published in the journal Gut Microbes, is believed to be the first to find a potential link between endocannabinoids, exercise and gut microbes.

"Our study clearly shows that exercise increases the body's own cannabis-type substances. Which can have a positive impact on many conditions,” says lead author Amrita Vijay, a Research Fellow at Nottingham’s School of Medicine. "As interest in cannabidiol oil and other supplements increases, it is important to know that simple lifestyle interventions like exercise can modulate endocannabinoids."

Vijay and her colleagues enrolled 78 people in their study. Half of the participants did 15 minutes of muscle strengthening exercises every day for six weeks, and the rest did nothing. Blood and fecal samples were collected from both groups.

At the end of the study, participants who exercised not only had lower pain levels, they also had significantly more Bifidobacteria and Coprococcus 3 -- bacteria that produce anti-inflammatory substances and lower levels of cytokines, which regulate inflammation.

These gut bacteria were particularly adept at raising levels of short chain fatty acids (SCFAs), which increase levels of endocannabinoids. About a third of the anti-inflammatory effects of the gut microbes was due to their ability to raise endocannabinoid levels.

Importantly, the exercise group also had lower levels of Collinsella – a bacteria known to increase inflammation that is strongly associated with processed food and diets low in vegetables.    

“In this study we show that circulating levels of ECs (endocannabinoids) are consistently associated with higher levels of SCFAs, with higher microbiome diversity and with lower levels of the pro-inflammatory genus Collinsella. We also show statistically that the anti-inflammatory effects of SCFAs are up to one third mediated by the EC system,” researchers concluded.

Previous studies have also found an association between gut bacteria and painful conditions. A 2019 study at McGill University found that women with fibromyalgia had 19 different species of bacteria that were present in either greater or lesser quantities than a healthy control group.

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

Having a healthy diet can also affect pain levels for migraine, neuropathy and other types of chronic pain. A recent study funded by the National Institutes of Health found that migraine sufferers who ate more fatty fish and reduced their consumption of polyunsaturated vegetable oils — frequently found in processed foods — had fewer headaches.