The unexplained beneficial effects of cannabis for Crohn's disease sufferers just got stranger with researchers from Israel finding cannabis oil significantly improves patient symptoms yet, unexpectedly, has little effect on reducing gut inflammation.

"Cannabis has been used for centuries to treat a wide range of medical conditions, and studies have shown that many people with Crohn's disease use cannabis regularly to relieve their symptoms," explains lead researcher Timna Naftali on the origins of his research.

Researchers have long thought the anecdotal beneficial effects of cannabis on Crohn's disease was due to a possible anti-inflammatory effect, however no explicit underlying mechanism explaining this has so far been discovered. A study released earlier in 2018 hypothesized a new mechanism that could explain how cannabis reduces gut inflammation, but at this stage it has only been demonstrated in mouse models.

The new study from an Israeli team, as yet not peer-reviewed or published, set out to clearly identify the anti-inflammatory properties of cannabis by recruiting 46 patients with Crohn's disease. The randomized control trial administered half the cohort with an eight-week treatment of cannabis oil, and the other half with a placebo. As well as monitoring symptom severity, the researchers measured inflammation in the gut both endoscopically and via biomarkers in blood and stool.

The results were striking, with 65 percent of subjects in the cannabis group demonstrating full clinical remission in their symptoms after the eight weeks of treatment, while only 35 percent of the placebo group met remission criteria at the end of the study. But the most compelling aspect of the study was the finding that inflammatory markers in the cannabis group remained unchanged, despite the significant symptomatic improvements.

"We have previously demonstrated that cannabis can produce measurable improvements in Crohn's disease symptoms but, to our surprise, we saw no statistically significant improvements in endoscopic scores or in the inflammatory markers we measured in the cannabis oil group compared with the placebo group," says Naftali.

At this stage these results suggest that any improvement in Crohn's disease resulting from cannabis consumption may not be related to an anti-inflammatory effect. Whether this means cannabinoids interact with a wholly undiscovered biological system in relation to Crohn's disease is yet to be shown, but we do know that compounds in cannabis can produce anti-inflammatory effects. So this study adds to the mystery of how cannabis may help sufferers of Crohn's disease, even if it potentially isn't directly reducing gut inflammation.

"There are very good grounds to believe that the endocannabinoid system is a potential therapeutic target in Crohn's disease and other gastrointestinal diseases," says Naftali. "For now, however, we can only consider medicinal cannabis as an alternative or additional intervention that provides temporary symptom relief for some people with Crohn's disease."

The new study was presented recently at UEG Week Vienna, 2018.