Patients with inflammatory bowel disease may benefit from cannabis-based drugs, UK scientists believe.
The compounds share some properties with cannabis
The Bath University team found people with the gut disorder had an abundant number of a type of cannabinoid receptors in their body.
They believe this is part of the body's attempt to dampen down the inflammation and that giving a drug that binds to these receptors could boost this.
Their findings appear in the journal Gastroenterology.
When people have Crohn's disease or ulcerative colitis - collectively known as inflammatory bowel disease or IBD - their immune system goes into overdrive, producing inflammation in different areas of the digestive tract.
This causes symptoms such as pain and urgent diarrhoea.
Anecdotally, people with IBD who have been users of cannabis have reported that their symptoms get better when they use the drug.
Dr Karen Wright and colleagues examined gut samples from healthy people and IBD patients and looked for the presence of two receptors known to react to natural cannabis-like compounds produced by the body.
Both the patients and the healthy people had similar numbers of CB1 receptors in their gut. However, the IBD patients had far greater numbers of CB2 receptors.
The normal job of CB1 and CB2 receptors is to switch immune responses on or off. CB1 receptors also help to promote wound healing in the lining of the gut.
Dr Wright said: "This gives us the first evidence that very selective cannabis-derived treatments may be useful as future therapeutic strategies in the treatment of Crohn's and ulcerative colitis.
"This is because some extracts from cannabis, known as cannabinoids, closely resemble molecules that occur naturally in our body, and by developing treatments that target this system, we can help the body recover from some of the effects of these diseases."
She said that the psychoactive effects and the legal implications associated with herbal cannabis use made it unsuitable as a treatment.
However, it might be possible to make a synthetic cannabis-like drug that has all of the therapeutic benefits and none of the other actions of cannabis.
"Targeting drug development to components of the in-built cannabinoid system could be the way forward," she said.
Dr Derek Scott, a researcher in Biomedical Sciences at Aberdeen University, said: "These initial results look extremely promising and exciting.
"However, further work is required so that we can better understand exactly how the signalling pathways controlled by cannabinoid receptors might be targeted in IBD patients, and whether there might be any side-effects."
Cannabis-based medicines are already used for multiple sclerosis in some countries.
Dr John Zycheck, from the Peninsula Medical School in Plymouth, which has been granted £2 million to study these drugs for MS, said: "There is no reason why clinical studies could not be undertaken at a fairly early stage because we are already testing cannabinoids for a variety of different conditions.
"Cannabinoids do have an effect on the gut. It slows gut transit. We see it in our MS patients."
He said more work was needed to check whether these drugs would reduce inflammation and to work out a dose that was strong enough but not toxic.
Dr George Kunos from the US National Institutes of Health said an alternative approach could involve testing compounds that amplify the action of the body's natural cannabinoids by blocking their normal destruction in the gut.
He said animal studies suggested compounds that block the enzyme fatty acid amidohydrolase (FAAH) do this.
Dr John Bennett, Chairman of Core, a national gut and liver disorders charity, said: "I would not want any patient to think that a cannabis-based treatment for IBD is around the corner. Much more work is needed."