Researchers at the University of Gothenburg have identified clear links between the composition of gut bacteria and frailty in older women, according to a study published on Jul. 8. The study found that high frailty, associated with increased risk of illness and death, corresponds to lower gut bacterial diversity and impaired function.
The research is based on data from 2,081 Swedish women aged 75–80. It demonstrates that frailty is linked to both lower diversity and poorer functional capacity of the gut microbiota. These findings were largely confirmed by an independent Chinese cohort comprising 1,448 older men and women.
Frailty is described as a common geriatric condition marked by greater vulnerability to disease, falls, functional impairment, and death. The researchers analyzed genetic material from participants' gut microbiota in relation to their degree of frailty and related clinical outcomes.
To assess frailty levels, the team used the Frailty Mortality Index (FMI), which combines functional, physiological, and psychological dimensions connected to frailty and mortality risk. Results show that a higher FMI score—indicating greater estimated frailty—is associated with lower microbial diversity, fewer microbial genes, and reduced predicted functional capacity within the gut microbiota. These features were also linked to physical function decline, mortality rates, and fall-related injuries.
A total of 404 bacterial species were found significantly associated with FMI scores; many associations appeared in both Swedish and Chinese cohorts. This suggests some microbial signatures related to frailty may be shared across different populations.
Mattias Lorentzon, Professor at the University of Gothenburg and Senior Consultant at Sahlgrenska University Hospital, said: "Frailty is a complex condition, and our findings suggest that the gut microbiota may be an important part of the overall picture. The next step is to investigate whether these microbial patterns can aid in risk assessment or form the basis for future interventions." The researchers note that while their study shows associations between microbiota characteristics and frailty indicators rather than causation or intervention effects.
