When I’ve imagined a future framed by frailty — the heightened risk of falling, the daunting stairways, the sapping of strength — a regular strength-training regimen has always seemed to be the most prudent response. Hoisting heavy objects, I figured, would keep my body from slipping into such a weakened state. Recent research, however, suggests that it’s not just how I work my muscles as I grow older; it’s how I feed my gut.
The gut microbiome and its complex mix of microbes have inspired a good deal of scientific exploration in recent years. And the results of all that research have gradually led to a kind of consensus: What’s going on in our guts may affect everything from cognitive function and mood to cardiovascular disease and type 2 diabetes. The proper combination of bacteria, fungi, and viruses can protect the gut lining, ease inflammation, and boost immunity; too little diversity in that microbial community — a common result of aging — or an overabundance of harmful types of microbes can cause problems throughout the body.
Perhaps even to the point of producing frailty.
Researchers at Sweden’s University of Gothenburg last week released the results of a study showing a clear association between an unhealthy gut microbiome and frailty among a large cohort of older women.
“While aging alters gut microbiota composition and function, gut microbiome profiles observed in frailty differ from those associated with healthy aging, reflecting not just chronological age but also deterioration of physiological process,” study coauthor Marina Vilar Geraldi, PhD, a postdoctoral researcher in the Department of Internal Medicine and Clinical Nutrition, writes in Nature Communications. “Understanding these frailty-associated microbiome features is critical for designing interventions to prevent or delay age-related health deterioration.”
Vilar Geraldi and her team analyzed health data from 2,081 Swedish women between the ages of 75 and 80 who participated in the national SUPERB study, which charted their health and mortality for an average of 7.9 years. Researchers created a Frailty Mortality Index (FMI), which measured a participant’s degree of frailty based on fall-related injuries, hip fractures, and overall risk of mortality. Those in the “severe” FMI group, for instance, were characterized by older age and a higher prevalence of smoking, among other lifestyle factors. They were also weaker, exhibiting slower walking speed, fewer chair stands, and less grip strength.
Researchers examined overall gut microbiome diversity and functionality in each of the participants and, after accounting for a wide range of diseases and accompanying medication usage, found that those who displayed more severe signs of frailty also exhibited an unhealthy mix of microbes in their guts.
“Our results align with evidence that gut microbiota composition influences system inflammation [and] physical and cognitive function, which are key components of frailty,” Vilar Geraldi concludes.
But does an unhealthy gut microbiome actually cause frailty? Or is that microbial mess simply a byproduct of a severely frail condition? The results of the study, she notes, do not offer a conclusive answer: “The cross-sectional nature of the analysis precludes causal inference, making it difficult to determine whether gut microbial changes precede frailty onset or are a consequence of aging-related physiological decline.”
So, should I continue my strength-training regimen with renewed confidence that it will deliver me from a future of frailty? (Gut-healing dietary strategies, after all, can be challenging.) Maybe, but if gut health is indeed what really matters, there’s apparently little evidence to suggest that all that lifting will make a difference.
A 2024 meta-analysis of seven studies focusing on the relationship between resistance training and gut health concluded that none of the research found “significant change in the gut microbiome” as a result of such a regimen.
And yet . . . there’s this: “It is extremely difficult to isolate the direct effect of resistance training due to the other factors that can interact with and modify the human gut microbiome,” the authors admit. “Not all the included studies controlled for all these factors, especially diet which is a major confounding factor.”
All of which suggests to me that the consensus on this particular condition may be a bit more frail than those of us seeking its guidance. Might as well keep lifting.
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