A team from the RIKEN Center for Integrative Medical Sciences, Japan’s largest comprehensive research institution, uncovered why smoking appears to protect people with ulcerative colitis (UC), a chronic bowel disease. The study, published today (August 25) in Gut, found that smoking produces metabolites such as hydroquinone, which allow oral bacteria like Streptococcus mitis to colonize the gut. In UC patients, these bacteria trigger an immune response that reduces inflammation.
The effect does not extend to Crohn’s disease, where the same immune reaction makes symptoms worse.
Lead researcher Hiroshi Ohno said the discovery could pave the way for new probiotic or prebiotic therapies that replicate smoking’s benefits without its health risks.