Gut Microbiota and Unhealthy Aging

Contributed by Carol Huang, Sr. Research Specialist                      @BartWeimersLab

The equilibrium of gut microbiota is fundamental to our health. The gut microbiota composition established at birth which changes with aging, diet, health condition and other factors.  As growing up the dynamic nature of gut microbiota getting built up, diversified and stabilized till middle age.  At older age, the profound changes occur again. During this long process, the composition may be regulated by diet. The dominant microbiota is a signature for each individual, but it always retains the imprint of the early childhood profile.  A recent published review paper discussed factors that  have impact on gut microbiota and unhealthy aging (Cell Host & Microbe 28, August 12, 2020, p.180-189)

The gut microbe organism composition may be modified by aging related gut physiological changes, food structure, lifestyle and geological living conditions. All these factors would contribute to the changes in some microbiome members. Around 60 bacterial species are carried by 50% of individuals in the same geographic area. Studies shown that upon their roles and functions in the community, the changes on level of some species are related diseases and unhealthy aging.  Low levels of beneficial microbes like Akkarmansiaceae, shown in obesity, diabetes and HIV cases and high level of which in Healthy colons, while low level of Bifidobacterium shown in HIV cases and high in centenarians. Microbes like Clostridiaceae, Bidobacteriaceae, Lachnospiraceae Coriobacteriaceae are related to immune senescence. In model study shown that preventing of age-related changes in intestinal physiology would reduce microbial imbalance and extends lifespan.

The review discussed the role of inflammation as drive of gut permeability and microbial dysbiosis. The slowly increased chronic inflammation is a character of aging, chronic health and age-related metabolic conditions. Inflammation caused aging impacts gut integrity and is linked to specific microbiota changes. Observation shows all chronic inflammatory conditions are associated with microbial dysbiosis. In response to inflammation some specific microbial niches are lost or disordered. Increased expression of inflammatory cytokines can decrease expression of tight junction proteins and lead to increasing permeability and further to retain inflammation.

The age-related intestinal function changes are not clear, but it has been reported that increased paracellular permeability colonic transit is likely due to physiologic changes in the aging gut. Studies have found that the extreme longevity individuals tend to have a more diversified gut microbiota and greater number of microbial taxa than less healthy individuals.

Physiology difference between genders plays a role in age-related immune disfunction and further to microbiome imbalance. Hormonal difference makes different microbiome abundance in gut physiology, such as adipose distribution, glucose metabolism, and specific inflammatory mediators likely contribute to age-related immune dysfunction and ultimately contribute to microbial dysbiosis.

To promote healthy aging, we need to understand the interactions between host and gut microbial community, intervene within the microbiome community.  It might not be easy to change the aging microbiome, which changed due to gut physiological change. Interventions can be fulfilled by change diet for more favorable environment to beneficials microbiomes abundance and reduce inflammatory conditions; promote more diversified microbiota community and reduce microbial dysbiosis; provide proper balanced nutrient, prebiotics, control antibiotic intake, to some degree can supplement probiotics. Keep healthy lifestyle physically and mentally, being active are also very important for healthy aging process.

Ref:  The Gut Microbiota and Unhealthy Aging: Disentangling Cause from Consequence.  Cell Host & Microbe 28, August 12, 2020, p.180-189 ( https://doi.org/10.1016/j.cell.2020.08.017)

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