Understanding Inflammatory Bowel Disease (IBD): Genes, Diet, and Gut Microbiota. Inflammatory bowel disease (IBD) is a chronic condition causing debilitating symptoms like abdominal pain, diarrhea, and weight loss. While genetics play a role, the exact environmental triggers remain unknown. A new University of Michigan (U-M) study sheds light on the complex interplay between diet, genes, and gut bacteria in IBD development.
IBD Genes and the Immune System
Some people with a genetic loss of the immune system protein interleukin-10 (IL-10) develop IBD early in life. The U-M study used mice with this genetic alteration to explore this connection further.
While some mice developed intestinal inflammation, the severity varied. Interestingly, the absence of gut bacteria completely prevented the disease.
The researchers observed they could control inflammation in the mice by manipulating the presence of a human gut microbiome model and dietary fiber content. Certain bacteria, like Akkermansia mucinphila and Bacteroides caccae, thrived on a low-fiber diet and worsened inflammation by eroding the protective mucus layer in the intestine.
“These bacteria weaken the gut barrier by eating away at the mucus layer, bringing them closer to the tissue,” explained Dr. Martens, a professor at U-M Medical School. “This proximity triggers inflammation in mice with IBD genetics.”
Diet’s Role in IBD
A fiber-rich diet prevented inflammation in the mice. Even switching mice from a low-fiber to a high-fiber diet reduced inflammation, suggesting fiber can reverse the damage caused by mucus erosion.
Ironically, a formula-based diet lacking fiber (exclusive enteral nutrition or EEN) is often used to treat pediatric IBD despite the lack of fiber. While EEN reduces inflammation in humans, the reason was unclear.
The study revealed that EEN somehow elevated isobutyrate, a fatty acid produced by gut bacteria, in the mice. Isobutyrate appears to suppress inflammation.
“EEN might work by promoting the growth of bacteria that produce beneficial metabolites like isobutyrate,” Dr. Martens suggests.
Future Directions in IBD Treatment
These findings open new avenues for IBD treatment. Researchers plan to investigate how diet and gut bacteria interact to develop better therapies, particularly for pediatric IBD. They also aim to explore ways to potentially prevent or reverse IBD by manipulating these environmental triggers.
“We might be able to tailor dietary interventions to influence gut bacteria and alleviate inflammation,” says Dr. Pereira, the study’s first author. Understanding Inflammatory Bowel Disease (IBD): Genes, Diet, and Gut Microbiota.