We’ve figured out why marijuana helps inflammation.

Popular Science looks at Mary Jane, gut problems and the mechanism behind cannabis helping make IBS better:

A new study from University of Massachusetts and University of Bath researchers is the first to demonstrate the physical process by which cannabis affects IBD, opening up the possibility of creating new drugs to treat these chronic ailments.

Although numerous IBD patients use cannabis products to help treat their illness, and the phenomena has been subject to some medical research, nobody knew exactly how the medically active parts of marijuana (known as cannabinoids) had an anti-inflammatory effect on irritated bowels before this study.

In the gut, a thin layer of epithelial cells mediates between our bodies and the microbial “zoo” living within. Beth McCormick of the University of Massachusetts has been studying the role these cells play in regulating the gut microbiome for well over a decade, and the starting point for this current research was her prior discovery of a chemical pathway by which epithelial cells help neutrophils, a kind of white blood cell, to cross into the gut and eat up some of the microbes. But that was clearly only half of the answer. In order to produce balance, something else had to stop too many neutrophils from getting in and killing peaceful microbes and even the gut itself—leading to IBD.

The answer, reported in the new study out Monday in the Journal of Clinical Investigation, is a different pathway, also in the epithelial cells of the gut lining. That chemical pathway produces substances that prevent neutrophils from getting through the epithelial cells and into the gut. And it turns out those substances, in mice at least, are endocannabinoids.

It would help explain why cannabinoids seem to provide relief for people with IBD, because they perform basically the same regulatory function as the endocannabinoids would if the body were producing them itself. More research, of course, is needed, but McCormick says it opens up the possibility of creating new IBD treatments that work on the new pathway—including, perhaps, therapeutic agents extracted from marijuana.