Aging gut bacteria linked to age-related diseases

Our gut is inhabited by a huge number of different kinds of bacterial species.  The bacterial species that are present can vary from person to person.  As we age, the composition pf bacterial species changes and often become imbalanced.  A study from the University Medical Center Groningen, Netherlands, published in journal Frontiers in Immunology, suggests that the imbalances in gut bacteria in the elderly may cause chronic inflammation, which leads to many age-related diseases.

“Inflammaging” is a term referring to low-grade chronic inflammation that has been linked to life-limiting conditions such as stroke, dementia and cardiovascular disease. Previous research shows that the elderly tends to have a different composition of gut bacteria than younger people. Immune responses also tend to be compromised in the elderly, resulting in inflammaging.  Knowing this, Netherlands team set out to investigate a potential link between inflammaging in elderly and gut bacteria.

The scientists transferred gut microbiota from old and young conventional mice to young germ-free mice.  Then, the scientists analyzed immune responses in the mice received transferred gut microbiota.  The results showed an immune response to bacteria transferred from the old mice but not from the young mice.

The results suggest that an imbalance of the bacterial composition in the gut may be the cause of inflammaging in the elderly. Imbalances, or “dysbiosis” of gut bacteria results in “bad” bacteria being more dominant than “good” bacteria. An overgrowth of bad bacteria can make the lining of the gut become more permeable, allowing toxins to enter the bloodstream where they can travel around the body with various negative effects. Dysbiosis can have serious health implications: several disorders, such as inflammatory bowel disease, obesity, diabetes, cancer, anxiety and autism are already linked to the condition.

Since inflammaging is thought to contribute to many diseases associated with ageing, and now we know that the gut microbiota plays a role in this process, strategies that alter the gut microbiota composition in the elderly could reduce inflammaging and promote healthy ageing.  Strategies that are known to alter gut microbiota composition include changes in diet, probiotics, and prebiotics, and exercising.

Thanks for reading.

Journal Reference: Lazar V. et al. Aspects of Gut Microbiota and Immune System Interactions in Infectious Diseases, Immunopathology, and Cancer, Front. Immunol., 15 August 2018 | https://doi.org/10.3389/fimmu.2018.01830