Prevalence of Roseburia Inulinivorans in the Gut Microbiome Affects Muscle Strength
The gut microbiome changes with age in ways that negatively affect tissue function and health. This is known because we live in an age in which it costs little to accurately measure the composition of the gut microbiome from a stool sample: which microbial species, and the relative abundance of each species. Bacterial species can be distinguished from one another by differing sequences of the 16S rRNA gene, so low-cost and relatively unsophisticated gene sequencing approaches can be used to characterize an individual's gut microbiome. The result is something of a golden age in the identification of new ways to adjust the gut microbiome to improve health.
Today's open access paper stands out as interesting, in that the authors establish a correlation between the prevalence of a single bacterial species, Roseburia inulinivorans, and muscle strength in mice and humans. The Roseburia inulinivorans population diminishes with age. Increasing the Roseburia inulinivorans population size via supplementation with live bacteria enhances muscle strength in mice. The size of that increase in strength was on the order of 30%, more than large enough to expect the emergence of a deluge of Roseburia inulinivorans live probiotic supplements in the years ahead. A trial of those supplements will be needed to determine the size of the effect on human muscle strength, but given the low cost of single species probiotic manufacture, that seems worth the effort.
Roseburia inulinivorans increases muscle strength
Gut bacteria have been implicated in a wide range of health conditions, yet their potential role in preventing and treating muscle-wasting disorders remains largely unexplored. We aimed to investigate whether specific gut microbial species are associated with muscle strength and to explore underlying mechanisms linking the gut microbiota to muscle health. We conducted metagenomic analyses in cohorts of younger and older adults extensively phenotyped for muscle strength. Associations were tested between bacterial taxa and performance measures. Causality was assessed by oral supplementation of candidate species in antibiotic-treated mice. Metabolomic profiling and muscle phenotyping were performed to elucidate mechanisms.
The relative abundance of Roseburia inulinivorans, but not other Roseburia species, was positively associated with multiple strength measures including handgrip, leg press, and bench press in humans. Supplementation of R. inulinivorans in mice significantly enhanced forelimb grip strength, whereas other Roseburia species had no effect. Metabolomic analyses revealed that R. inulinivorans reduced amino acid concentrations in the caecum and plasma, while activating the purine and pentose phosphate pathway in muscle. These changes coincided with increased muscle fibre size and a shift from type I to type II fibres. Accordingly, we observed that the relative abundance of R. inulinivorans is lower in older adults compared with young adults.
R. inulinivorans emerges as a species-specific modulator of muscle strength, linking gut microbiota to muscle metabolism and function. These findings support its potential as a probiotic candidate for nutraceutical interventions targeting age-related muscle-wasting diseases.