No one is quite sure what triggers inflammatory bowel disease, but there's a consensus as to what doesn't. Researchers no longer believe that diet and stress are main causes, although stress can often aggravate symptoms. Instead, current thinking focuses on the:

  • Immune system. Some scientists think a virus or bacterium may trigger IBD. The digestive tract becomes inflamed when your immune system tries to fight off the invading microorganism (pathogen). It's also possible that inflammation may stem from an autoimmune reaction in which your body mounts an immune response even though no pathogen is present.
  • Heredity. Because you're more likely to develop IBD if you have a parent or sibling with the disease, scientists suspect that genetic makeup may play a role. However, most people who have IBD don't have a family history of the disorder.
Dec. 13, 2012

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