Dr Byndloss on the Relationship Between the Gut Microbiome and GI Cancers

Mariana X. Byndloss, DVM, PhD, assistant professor, pathology, microbiology and immunology, Vanderbilt University Medical Center, discusses how the gut microbiome influences human health, highlighting the relationship between the gut microbiome and a person’s risk for developing gastrointestinal cancers, as well as characteristics of a healthy gut microbiome.A growing body of evidence indicates that the microbes that live in the human gut are important for maintaining health, Byndloss says, adding that these microbes are also important for the development of different diseases. As investigators have continued to study the characteristics of healthy microbiota, they have found critical signatures of healthy microbial communities, Byndloss explains. One of these signatures is the dominance of obligate anaerobic bacteria, including bacteroides species, which are bacteria that thrive in environments without oxygen, Byndloss says.

Bacteroides species promote health in multiple ways, such as by digesting components of the diet that humanscannot digest themselves, such as fiber, Byndloss expands. It is commonly understood that humans need a diet that is rich in fiber and vegetables because these contain nutrients that feed the beneficial microbes, which produce molecules to prevent inflammation and disease, Byndloss emphasizes.

However, investigators have found correlations between several human diseases and decreases in the dominance of the obligate anaerobic bacteria, which lead to expansions, or blooms, of other types of microbes, Byndloss says. These microbes are facultative anaerobic microbes, such as proteobacteria or enterobacteria acid, Byndloss continues. Examples of facultative anaerobic microbes include escherichia coli and salmonella typhimurium, which can cause disease, she says. This expansion of microbes is seen after treatment with antibiotics, as well as in multiple human diseases, ranging from necrotizing enterocolitis in infants, to inflammatory bowel disease, to colorectal cancer, Byndloss explains. The expansion of these microbes may be a critical sign of an issue within the intestinal microbiota, she concludes.