Like the gut microbiome, the composition of the oral microbiome changes with age. Some of these changes have been shown to correlate with health status, but research into this part of the commensal microbiome is nowhere near as advanced as is the case for the gut microbiome. It is unclear as to the degree to which the oral microbiome is causing issues in aging, even where mechanisms are known to exist, such as leakage of bacteria and bacterial products associated with gingivitis into the bloodstream. It is also unclear as to whether the classes of strategy shown to rejuvenate the composition of the gut microbiome can work effectively for the oral microbiome.
Evidence indicates that the composition of the oral microbiome changes with age, although findings on diversity are inconsistent, with reports of both increases and decreases in older adults. These shifts are influenced by factors such as diet, oral hygiene, and immune function. Unhealthy aging, including conditions like frailty, neurodegenerative diseases, and sarcopenia, is associated with distinct oral dysbiosis. Potential mechanisms linking the oral microbiome to aging include chronic inflammation and immunosenescence.
Although research on the oral microbiome is still in its early stage compared to that on the gut microbiome, existing studies still indicate a link between the oral microbiome and aging. The purpose of this review is to explore whether the oral microbiome, which serves as a common gateway for the microbiota of the respiratory and digestive systems, should be considered a target for predicting and delaying aging. We focus primarily on the changes in the oral microbiome during healthy aging, the characteristics of the oral microbiome in unhealthy aging states such as frailty and age-related diseases and the possible mechanisms underlying the association between the oral microbiome and aging. Finally, we summarize the current research findings and provide possible directions for microbiome-based aging interventions.
