Link Between Diet, Microbiome Composition, and Inflammatory Bowel Disease

Understanding Inflammatory Bowel Disease

Researchers have established a connection between dietary factors and remission in inflammatory bowel disease (IBD), a term that encompasses various disorders affecting the gastrointestinal tract, with Crohn’s disease being the most prevalent in humans. Extensive research has indicated that both environmental influences and genetic predispositions contribute to the development of IBD. A notable finding is that IBD patients often experience changes in gut microbiome composition, known as dysbiosis.

Influence of Diet on Microbiome Composition

The microbiome’s makeup is significantly influenced by dietary choices. Diets high in fat and low in fiber have been associated with IBD. In a recent study conducted by researchers from the University of Pennsylvania’s School of Veterinary Medicine, a canine model was utilized to explore the relationship between diet, IBD progression, and microbiome composition. This model is considered particularly effective for studying gastrointestinal disorders.

Study Design and Findings

The study involved 29 dogs diagnosed with chronic enteropathy, a condition akin to human IBD, which were placed on a hydrolyzed-protein diet. Researchers observed changes in the microbiome that correlated with disease remission in 20 of the 29 dogs. Notably, the microbiome of dogs that responded to the diet shifted toward that of healthy dogs after 14 days, showing a significant reduction in the relative abundance of E. coli and C. perfringens strains. In contrast, no microbiome changes were evident in dogs that did not respond to the dietary intervention.

Microbial Associations with Gastrointestinal Disorders

High levels of E. coli and C. perfringens have been previously linked to gastrointestinal disorders. The researchers proposed that the reduction of specific bacterial strains in the microbiome may be associated with disease remission. To delve deeper, they created a metabolic profile of the dogs’ fecal samples before, during, and after the dietary regimen. Elevated levels of secondary bile acids were found in the dogs that achieved remission, while such levels were absent in those that did not respond to the diet. Since elevated bile acids correlate with disease remission and reduced E. coli and C. perfringens, the team hypothesized that bile acids inhibit bacterial growth. Their in vitro tests confirmed that lithocholic and deoxycholic acids indeed suppressed the growth of these pathogenic strains.

Further Exploration of Microbial Populations

The researchers also discovered a higher abundance of C. hiranonis in the fecal samples of dogs that benefited from the dietary changes. To investigate the relationship between C. hiranonis, bile acids, and disease remission, they conducted experiments using C. hiranonis cultures to treat gastrointestinal inflammation in a mouse model. Results indicated a reduction in inflammation in mice treated with C. hiranonis compared to untreated controls.

Conclusion and Future Research Directions

In summary, this research underscores the significant impact of microbiome composition on IBD, highlighting the potential role of microbe-microbe interactions. Specifically, C. hiranonis may contribute to reducing pathogenic E. coli and C. perfringens through the production of secondary bile acids that inhibit their growth. The researchers recommend further investigations to determine why some individuals do not respond to dietary interventions and to identify which dietary components are crucial for mediating disease remission. Additional studies in both animal models and humans are necessary to build a comprehensive understanding that could inform the development of effective therapeutic diets.

Written by Bella Groisman, PhD
References: Shuai Wang, Daniel P. Beiting et al (2019), Diet-induced remission in chronic enteropathy is associated with altered microbial community structure and synthesis of secondary bile acids. Microbiome. volume 7, Article number: 126
News Release: (Sep 9, 2019), The diet-microbiome connection in inflammatory bowel disease: https://www.eurekalert.org/pub_releases/2019-09/uop-tdc090919.php
Image by Анастасия Гепп from Pixabay