Colitis

For decades, scientists have puzzled over why smoking makes Crohn’s disease worse but seems to protect people from ulcerative colitis. Now, researchers at RIKEN have discovered that smoking creates metabolites like hydroquinone that allow mouth bacteria—especially Streptococcus mitis—to settle in the gut. These bacteria spark an immune response that reduces inflammation in colitis but worsens Crohn’s. The findings open the door to new therapies using probiotics or targeted compounds that mimic smoking’s protective effects without its deadly risks.