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Gut bacterium Roseburia inulinivorans linked to greater muscle strength in humans and mice

A study in the journal Gut finds higher abundance of the microbe correlates with physical strength, raising its potential as a probiotic against age-related muscle loss.

Updated Aug 24, 2026 · 00:33 UTC1 reports

The short version

  • Researchers found that the gut bacterium Roseburia inulinivorans is associated with stronger muscles in humans and increased grip strength in mice.
  • Older adults with detectable levels of the bacterium displayed 29% greater handgrip strength, but the microbe's overall abundance was lower in older demographics compared to younger adults.
  • Treated mice developed larger fast-twitch muscle fibers and gained about 30% more forelimb grip strength across an eight-week trial.
  • Further research is required to prove whether the bacterium directly causes muscle changes or if its presence is merely a marker of better baseline physical condition.

Key facts

  • A study published in the journal Gut linked the bacterium Roseburia inulinivorans to greater muscle strength in both humans and mice.[ScienceDaily]
  • Older adults with detectable levels of R. inulinivorans had 29% higher handgrip strength than those without detectable levels, according to an analysis of 90 young and 33 older adults.[ScienceDaily]
  • Mice treated with R. inulinivorans for eight weeks showed an approximate 30% increase in forelimb grip strength and grew larger fast-twitch muscle fibers compared to controls.[ScienceDaily]
  • Roseburia species were found to be more abundant in younger adults (ranging up to 6.6% for R. inulinivorans) than in older adults (ranging up to 1.3%).[ScienceDaily]

What remains uncertain

  • Human Roseburia species did not permanently colonize the guts of the mice during the experiment.[ScienceDaily]
  • Long-term studies are needed to determine direct causation and rule out whether bacterial abundance is simply a consequence of better muscle health, as the trial did not fully investigate potential inflammatory or neuromuscular pathways.[ScienceDaily]

Sources