Pot improves symptoms of Crohn’s disease but — contrary to previous medical thinking — has no effect on gut inflammation.

That's the finding of a team of researchers from Israel led by Dr Timna Naftali. In the first study of its kind, Naftali’s team found that cannabis oil significantly relieved the symptoms of Crohn's disease and improved the quality of life of patients, even though it had no impact on gut inflammation.

Crohn's is a severe type of inflammatory bowel disease (IBD), a long-term condition that affects 10 million people worldwide. In IBD, the immune system attacks tissue in the gastrointestinal tract, causing inflammation.

In the case of Crohn's disease, the inflammation can occur in any part of the gut between the mouth and the anus.

Symptoms vary from person to person and can significantly impact quality of life. These can include diarrhoea, bleeding, constipation, abdominal pain, feeling an urgent need to go to the bathroom, and a sensation that the bowels have not been fully emptied.

Other symptoms of IBD, such as fatigue, appetite loss, weight loss, fever, and sweating at night, can accompany these.

Another major type of IBD is ulcerative colitis, which mainly affects the colon or large intestine.

Crohn’s can also have severe complications such as malnutrition, bacterial overgrowth, intestinal blockages, and ulcers.

“60 to 75% of Crohn’s patients may require surgery at some stage due to possible complications. The type of procedure will vary depending on the severity and location of the disease in the intestines,” said Naftali, who is a gastroenterology specialist at Tel Aviv University's Meir Hospital and Kupat Holim Clinic in Israel.

The randomised, placebo-controlled study showed that cannabis can produce clinical remission in up to 65% of individuals after eight weeks of treatment, but that this improvement doesn’t appear to result from a dampening down of the underlying inflammatory process.

Presenting the study findings at the United European Gastroenterology annual meeting (UEG Week 2018) in Vienna, Naftali explained: “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. It has always been thought that this improvement was related to a reduction in inflammation in the gut and the aim of this study was to investigate this."

The Israeli team recruited 46 people with moderately severe Crohn's disease, and randomised them to receive eight weeks of treatment with either cannabis oil containing 15% cannabidiol (CBD) and 4% tetrahydrocannabinol (THC) or placebo.

Symptom severity and quality of life were measured before, during, and after treatment, using validated research instruments. Inflammation in the gut was assessed endoscopically and by measuring inflammatory markers in blood and stool samples.

After eight weeks of treatment, the group receiving the cannabis oil had a significant reduction in their Crohn's symptoms, compared with the placebo group, and 65% met strict criteria for clinical remission (versus 35% of the placebo recipients). The cannabis group also had significant improvements in their quality of life compared with the placebo group.

"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," said Naftali.

"We know that cannabinoids can have profound anti-inflammatory effects, but this study indicates that the improvement in symptoms may not be related to these anti-inflammatory properties."

Looking forward, the research team plans to further investigate the potential anti-inflammatory properties of cannabis in the treatment of IBD.

"There are very good grounds to believe that the endocannabinoid system is a potential therapeutic target in Crohn's disease and other gastrointestinal diseases," said 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.”

This is just one encouraging study of many that illustrates how the legalisation of weed in an increasing number of countries can have a profound impact on medicinal research.