Frailty and the Microbiome.

From the moment of birth, the human body plays host to a rich diversity of microbes. Body sites such as the skin, the gut and the mouth support communities of microorganisms (collectively known as the microbiome) that are both numerous and diverse. As our understanding of the microbiome advances, it is evident that these microbial populations participate in a multitude of symbiotic associations with us. The disruption of these associations can lead to a range of diseases beyond mere pathogenesis as microbial nutrition, signaling, and immune defense break down. It is known that changes in microbial composition occur as the human host ages and that diet and living conditions influence the microbiome of older individuals. However, the link between the microbiome and frailty is as yet mostly unexplored. Although the microbiome is likely to influence health factors that contribute to frailty, further work is needed to determine whether overall microbial signatures of frailty exist and, if so, what the diagnostic and therapeutic utility of these signatures might be.