Many people with gut trouble spend years brushing it off as a sensitive stomach.
By the time Crohn's disease or ulcerative colitis finally gets a name, the bowel may have been inflamed for a long time.
The body, it turns out, may have been flashing a warning much earlier.
A distinct antibody pattern in the blood may show up as much as 10 years before Crohn's disease or ulcerative colitis begins, according to new research.
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The findings were presented on October 19, 2026 at UEG Week in Barcelona by scientists from the University Medical Center Groningen in the Netherlands, according to EurekAlert.
The team studied 500 people in all. Two hundred later developed Crohn's disease, 200 developed ulcerative colitis, and 100 stayed healthy. Across their 2,000 blood samples, researchers detected 123,980 unique antibodies.
What the blood revealed years before symptoms
People who later developed IBD had less variety in their antibodies than those who stayed healthy.
They also showed stronger immune responses against herpesviruses, and in future Crohn's patients against a bacterial protein called flagellin.
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The pattern was most striking in people who later developed the harder forms of Crohn's, including the type that attacks the end of the small bowel. At the same time, responses to a group of protective, capsule-coated bacteria dropped as diagnosis drew closer.
How well the test performed
A machine learning model was trained to spot future patients from these antibody patterns. For Crohn's, it was right roughly nine times out of ten. For ulcerative colitis, it was right about eight times out of ten.
The same model also separated people heading for complicated Crohn's from those heading for a milder form, with similar accuracy. That matters because the harder forms often need stronger treatment much sooner.
Dr. Arno Bourgonje, who led the research, said in the press release that the severe form of Crohn's appears to leave an antibody signature long before any symptoms arrive.
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That suggests it is not simply the result of disease worsening after diagnosis, but a different biological course from the start.
What this still is and is not
For now, this is a research finding, not a test anyone can ask for at the clinic. The researchers stress that the signatures must still be checked in larger and more diverse groups of people before any screening could follow.
If that validation holds up, a blood test could one day flag people at high risk years before damage sets in.
Treatment for IBD generally works better when inflammation has not yet scarred the bowel.
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How common Crohn's and colitis already are
Inflammatory bowel disease is already widespread. In the United States, about 4.1 million adults have ever been diagnosed with IBD, according to the CDC's National Center for Health Statistics. Ulcerative colitis is more than twice as common as Crohn's.
Anyone with ongoing stomach pain, bloody stools, lasting diarrhea or unexplained weight loss should raise it with a doctor rather than wait.
Those are among the signs covered in our rundown of warning signs that gut trouble could be Crohn's rather than a routine stomach complaint.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.