Strong muscles start in the gut
Researchers from the LUMC and the Universities of Granada and Almería have found a gut bacterium that is associated with stronger muscles in people and mice. Their findings, published in the journal Gut, hint at the potential for new probiotics to support muscle strength and healthy ageing.
‘As we grow older, our muscles naturally lose strength and size,’ postdoc Borja Martínez-Téllez explains. ‘That loss can make everyday tasks harder and increase the risk of falls, frailty and loss of independence. In more severe cases, muscle wasting can seriously affect health and recovery.’
While exercise and good nutrition remain important for maintaining muscle strength, scientists are now turning their attention to a lesser-known player: the gut. ‘The bacteria living in our intestines help us process nutrients, regulate inflammation and manage energy,’ Patrick Rensen, Professor of Endocrinology, notes. ‘All of these processes are essential for keeping our muscles healthy as we age.’
A gut bacterium linked to stronger muscles
In their new work, the researchers identified one particular gut bacterium, Roseburia inulinivorans, that appears to be linked to stronger muscles across the lifespan. ‘When we compared young adults aged 18 to 25 with older adults aged 65 and above, we noticed clear differences,’ Martínez-Téllez says. ‘Older adults who carried this bacterium had 29 per cent stronger handgrip strength than those who didn’t.’ In young adults, higher levels of Roseburia inulinivorans were associated with stronger muscles and better overall fitness. ‘It was remarkable to see the same pattern in both age groups,’ Martínez-Téllez adds.
Testing the bacterium in mice
To find out whether this link was more than a coincidence, the researchers carried out a series of experiments in mice. ‘We wanted to understand whether this bacterium actually causes improvements in muscle strength,’ Rensen explains. After clearing the mice’s gut bacteria with antibiotics, they introduced human strains of Roseburia inulinivorans for eight weeks. ‘The results were striking,’ Rensen says. ‘The mice became 30 per cent stronger, developed larger muscle fibres and produced more fast-twitch fibres, the kind needed for quick, powerful movements.’
The team also found that the bacterium changed how the muscles used certain building blocks and activated energy-related pathways inside the muscle. ‘These metabolic changes may help explain why the muscles grew stronger,’ according to Martínez-Téllez.
Potential probiotic treatment
Another key observation is that levels of Roseburia inulinivorans naturally decline with age. ‘This could partly explain why muscle strength drops as we get older,’ Martínez-Téllez says. ‘If this bacterium supports muscle metabolism, then restoring it might one day help preserve muscle function later in life.’
Together, the findings published in the journal Gut suggest that Roseburia inulinivorans could become a future probiotic, developed into a safe, supplement-like product aimed at preventing age-related muscle-wasting conditions. ‘A nutraceutical approach – using food-based or naturally derived products – could be a gentle, non-invasive way to support healthy ageing,’ Martínez-Téllez explains.
Looking ahead
The team is optimistic about where this discovery might lead. ‘We see so much potential in this bacterium that we have already secured a patent for its use in preserving and improving muscle mass and strength,’ Rensen says.
But they stress that more research is needed. ‘It is not ready for use as a treatment, but the early findings are highly encouraging’ says Rensen. ‘Further studies in humans will be crucial.’
‘It’s exciting to think that something as small as a gut bacterium might one day help us stay stronger and healthier as we age’, Martínez-Téllez adds.
Financial support and collaborations
This research received funding from the Leiden University Fund, Fundación Martín Escudero and Fondo de Investigación Sanitaria (Instituto de Salud Carlos III) and was a collaboration between Professor Patrick Rensen’s research group (Endocrinology Division, Department of Internal Medicine and Einthoven Laboratory, LUMC) and the universities of Groningen, Granada, Almería, Valencia and Cádiz.