The human gut is home to trillions of microorganisms, collectively known as the gut microbiome, which influence overall health. Among these, Parabacteroides distasonis is a common resident of the human intestines. Research continues to uncover its diverse roles, shedding light on new avenues for maintaining gut well-being.
Understanding Parabacteroides distasonis
Parabacteroides distasonis is a Gram-negative, anaerobic bacterium belonging to the phylum Bacteroidota, a prominent group within the human gut microbiome. It thrives in oxygen-free environments, typical of the large intestine. First isolated in 1933, it was initially classified as Bacteroides distasonis.
In 2006, genetic analysis led to its reclassification into the new genus Parabacteroides. This bacterium is saccharolytic, meaning it can metabolize carbohydrates for energy, and it exhibits resistance to oxidative stress.
Its Role in Gut Function
Parabacteroides distasonis breaks down complex carbohydrates that human enzymes cannot digest. It ferments dietary fibers and resistant starches, producing short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate. These SCFAs serve as a primary energy source for colon cells, supporting their health and function.
Butyrate, in particular, enhances the integrity of the gut barrier by strengthening tight junctions that seal the intestinal lining. By contributing to SCFA production, P. distasonis helps maintain a balanced gut environment, influencing the growth of other beneficial microbes and competing with less desirable ones.
Connections to Health and Disease
Parabacteroides distasonis has been associated with various health conditions, demonstrating both beneficial and, in some contexts, potentially detrimental roles. Its anti-inflammatory properties are an area of significant research, as studies suggest its potential in modulating immune responses. For instance, P. distasonis has been found to reduce inflammation in experimental models of colitis and has shown the ability to decrease weight gain, hyperglycemia, and hepatic steatosis in mice models of obesity and metabolic syndrome.
This bacterium also influences metabolic health, with links to improved glucose metabolism and insulin sensitivity, partly by modifying bile acid profiles. Research suggests its association with conditions such as inflammatory bowel disease, colorectal cancer, hepatic fibrosis, and fatty liver disease, often through its impact on the host immune system, intestinal barrier function, and metabolic networks. While generally considered beneficial, some experimental data suggest a dual role, with certain strains potentially exhibiting pro-inflammatory effects.
Modulating Its Presence
The levels and activity of Parabacteroides distasonis in the gut can be influenced by various factors, with diet playing a significant role. Consuming fiber-rich foods, particularly those containing prebiotics like inulin, can support its growth and activity. Inulin, a soluble fiber, has been shown to enrich P. distasonis in the gut and lead to the production of beneficial metabolites.
While P. distasonis is being explored as a potential next-generation probiotic, its direct inclusion in probiotic supplements is not yet widespread. However, certain dietary or lifestyle interventions that support a diverse and healthy gut microbiome may indirectly promote its presence. The potential use of P. distasonis-derived secondary bile acids as “postbiotics” for therapeutic purposes is also an area of ongoing investigation.