Why a diet rich in saturated fat can trigger bowel disorders

Dionysios Antonopoulos, an assistant biologist (microbiologist) in the Institute for Genomics and Systems Biology at Argonne National Laboratory, is co-author (with Suzanne Devkota, Bana Jabri, Eugene Chang, and others at the University of Chicago) of a new study on the role that diet plays in promoting complex immune disorders such as inflammatory bowel disease (IBD).

The study, which appeared in the online version of the journal Nature on June 13, provides new insights into why some people are more likely than others to develop IBD.

“For over a decade, researchers have known that gene variants can increase risk for such disorders, “said Antonopoulos. “Our new study, however, shows that environmental factors like diet may actually precipitate the development of the disease by triggering a shift in the microbial community structure of the gut that then triggers and amplifies the immune response.”

Working with a mouse model, Antonopoulos and his colleagues traced both the shift in the microbial community structure and the corresponding host immune response to a diet high in saturated (milk-derived) fats. To dissolve such fats, the liver produces a form of bile rich in sulfur. The researchers found that when the bile reaches the intestines, a microbe called Bilophila wadsworthia – the name means “bile loving” – blooms, or expands. Such blooms can trigger the immune system in people with a genetic predisposition. Moreover, the byproducts of this microbe’s interaction with bile can amplify the effect, making the bowel more permeable and unleashing an unregulated immune response in individuals at high risk for diseases such as IBD.

“Our work raises the possibility that scientists may be able to manipulate the bowel’s ecosystem, restoring homeostasis between the immune system and normally beneficial bacteria,” said Antonopoulos.

This research was supported by the National Institutes of Health, the Gastrointestinal Research Foundation, the Crohn’s & Colitis Foundation of America, the Peter D. and Carol Goldman Foundation, and the Leona M. and Harry B. Helmsley Charitable Trust.

For further information, see the full article:
S. Devkota, Y. Wang, M. W. Musch, V. Leone, H. Fehlner-Peach, A. Nadimpalli, D. A. Antonopoulos, B. Jabri, and E. B. Chang, “Dietary-fat-induced taurocholic acid promotes pathobiont expansion and colitis in Il10?/? mice,” Nature, 13 June 2012, doi:10.1038/nature11225


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