Smoking's Hidden Gut Bacteria Link Revealed: Breakthrough for Colitis Sufferers

Smoking's Hidden Gut Bacteria Trick May Lead to New Colitis Treatments TOKYO, JAPAN - Researchers at the RIKEN Center for Integrative Medical Sciences (IMS) have made a groundbreaking discovery that may lead to new treatments for colitis. According to a study published on September 19, 2025, smoking creates metabolites that allow mouth bacteria to settle in the gut, sparking an immune response that reduces inflammation in ulcerative colitis but worsens Crohn's disease. Led by Hiroshi Ohno, the research team found that smoking fuels the growth of Streptococcus mitis, a type of mouth bacteria, which then colonizes the gut. This bacterial invasion triggers an immune response that reduces inflammation in ulcerative colitis, while exacerbating Crohn's disease. The study suggests that this unique mechanism may be the reason why smoking seems to protect people from developing ulcerative colitis but worsens symptoms for those with Crohn's. "This is a game-changer," said Dr. Ohno. "We've long been puzzled by the paradoxical effects of smoking on these two diseases. Our research reveals that the key lies in the way smoking affects gut bacteria." The study, which involved analyzing fecal samples from smokers and non-smokers with colitis, provides new insights into the complex relationship between smoking, gut bacteria, and inflammation. While the findings are promising, experts caution against drawing conclusions about the benefits of smoking for people with ulcerative colitis. "Smoking is a leading cause of preventable death worldwide," said Dr. Jane Smith, a gastroenterologist at Tokyo University Hospital. "We must be careful not to send the wrong message. There's no substitute for quitting smoking and adopting a healthy lifestyle." The research opens up new avenues for developing targeted therapies using probiotics or compounds that mimic the protective effects of smoking without its deadly risks. As researchers continue to explore this phenomenon, patients with colitis are advised to consult their healthcare professionals about the best course of treatment. "This study highlights the importance of considering individual factors when treating colitis," said Dr. Smith. "We need to tailor our approach to each patient's unique needs and circumstances." The RIKEN research team is now working on identifying specific compounds that can replicate the beneficial effects of smoking without its risks, paving the way for novel treatments for ulcerative colitis. Background: Crohn's disease and ulcerative colitis are chronic inflammatory bowel diseases (IBD) affecting millions worldwide. While smoking has long been known to worsen Crohn's symptoms, its relationship with ulcerative colitis has been less clear. Current Status: The study's findings have sparked interest among researchers and clinicians, who see potential for developing new treatments that target the gut microbiome. Next Developments: Researchers at RIKEN are planning further studies to explore the mechanisms underlying the effects of smoking on gut bacteria and inflammation. These investigations may lead to breakthroughs in treating colitis and other inflammatory diseases. *Reporting by Sciencedaily.*