The connection between gut health and overall physical fitness has been recognized for decades; however, recent research illuminates the profound role gut bacteria play in maintaining muscle mass and function, especially as individuals age. A new study published in Aging Cell underlines the potential of probiotics as a therapeutic avenue for countering sarcopenia, a condition characterized by age-related muscle loss.

The interplay between gut bacteria and health is well-documented, with numerous studies confirming that a robust gut microbiome leads to enhanced health outcomes across various systems in the body [1]. Importantly, research conducted on murine models devoid of existing gut bacteria has shown that the reintroduction of beneficial bacteria correlates with improved muscle health [2]. Mechanistically, beneficial bacteria produce short-chain fatty acids (SCFAs), which have been implicated in muscle health enhancement within rodent studies [3].

This study further investigates the gut microbiome of elderly individuals, particularly focusing on those with and without sarcopenia, to explore effective clinical therapies that harness gut bacteria populations to mitigate frailty.

People with Sarcopenia Have Different Gut Bacteria

The research sample included 51 participants, averaging 74.5 years of age, with approximately 75% being women. Of these individuals, 28 were diagnosed with sarcopenia and 23 were not.

Findings indicated that individuals with sarcopenia exhibited significantly lower levels of both acetic acid and butyric acid, which are essential SCFAs. The study also noted a trend toward a decrease in overall SCFA levels, though this did not reach statistical significance. Furthermore, it was revealed that the gut microbiota profiles differed markedly between the two groups, with a total of 37 metabolites identified as distinct, particularly purines.

  • Participants with sarcopenia demonstrated decreased levels of Clostridiales and Lachnospira species.
  • They had an increase in Butyricimonas virosa, a pathogenic bacterium, despite its ability to produce butyric acid [4].
  • Among the evaluated probiotics, one was linked to muscle mass, while two correlated with improved physical performance.

To assess the effects of these bacterial populations, the study included an animal model consisting of four distinct groups of mice:

  1. Mice with gut bacteria from individuals with sarcopenia.
  2. Mice with gut bacteria from individuals without sarcopenia.
  3. Mice subjected to antibiotic treatment to eliminate their gut bacteria.
  4. A control group comprising unaffected mice.

After two weeks, results showed:

Group Grip Strength Twitch Force Muscle Mass
Antibiotic-treated Low Similar to Non-Sarcopenic Significantly Reduced
Sarcopenic Bacteria Lowest Lowest Lowest
Non-Sarcopenic Bacteria High Highest Normal

The mice receiving gut bacteria from sarcopenic individuals exhibited the weakest performance metrics, highlighting the adverse influence of such bacterial populations on muscle function.

A Probiotic Solution

Subsequently, the researchers explored the potential of specific probiotics: Lacticaseibacillus rhamnosus (LR) and Faecalibacterium prausnitzii (FP). Both are correlated with muscle health and function.

The experimental design involved administering these probiotics to mice beginning at 20-21 months of age over a three-month period alongside a control group. The following outcomes were noted:

  • Quadriceps and gastrocnemius muscle sizes improved across all treatment groups.
  • Grip strength and muscle force experienced improvement in treated groups compared to control.
  • Probiotic treatments delayed, but did not reverse, muscle loss associated with sarcopenia.

Moreover, the study reported favorable changes in metabolism, including:

Metabolic Factor Effects of Treatment
NRF1 Production Increase in mitochondrial biogenesis
NAD+/NADH Ratio Improved with individual probiotics; no improvement with combination
Gut Barrier Integrity Enhanced across all treatment regimens

While the probiotics derived from human bacteria showed promise in modulating muscle function and gut health, it is pivotal to note that these findings have yet to undergo clinical verification in human studies.

Advancements in this field underscore a pivotal role for probiotics as a potential intervention for sarcopenia, holding promise for improving the quality of life in the aging population.

Literature Cited

[1] Hou, K., et al. (2022). Microbiota in health and diseases.

[2] Lahiri, S., et al. (2019). The gut microbiota influences skeletal muscle mass and function in mice. Science Translational Medicine.

[3] Liu, C., et al. (2024). Short‐chain fatty acids enhance muscle mass and function through the activation of mTOR signaling pathways in sarcopenic mice. Journal of Cachexia, Sarcopenia and Muscle.

[4] García-Agudo, L., & Nilsen, E. (2018). Butyricimonas virosa: a rare cause of bacteremia. Anaerobe.

[5] Lifespan.io