Gut bacteria strengthen muscles and slow down aging

In recent years, scientists have increasingly found evidence that microbes in the gut affect not only digestion, but also brain function, immunity, and even the rate of aging. In a new study published in the journal Scientific Reports, scientists focused on the relationship between the gut microbiota and skeletal muscle health.

Physical activity has long been known as a factor that strengthens the immune system and reduces the risk of chronic diseases. However, it turned out that some of these effects are provided precisely through signals from microbes in the intestine. So far, this area has remained poorly understood, and the study has filled an important gap.

The experiments used elderly mice (9-12 months old), in which the intestines were first sterilized with antibiotics, and then the microbiota from healthy donors was implanted. After that, the animals were tested in strength and endurance tests: on a rotating drum (Rotarod) and in pull-ups on a wire.

The results were impressive. In mice treated with probiotic strains of L. reuteri and L. johnsonii, muscle mass increased by 157%, while the total body weight decreased. That is” the animals became more “dry” and stronger at the same time. A particularly pronounced effect was observed with a combination of two bacteria — it was then that the muscles increased the most, and endurance increased significantly.

Scientists have shown that bacteria affect key molecular pathways related to muscle growth.

• The activity of IGF-1, a factor that stimulates the growth of muscle cells, increased.
• The level of follistatin increased, which blocks myostatin— a protein that inhibits muscle growth.
• The levels of triglycerides and bad cholesterol (LDL) decreased, while the content of good cholesterol (HDL) increased.
• An anti-inflammatory effect was observed: The mice had decreased levels of interleukin-6, which is associated with chronic inflammatory processes.

Thus, probiotics simultaneously acted as “anabolics”, as metabolic regulators and as natural anti-inflammatory agents.

Although the results have so far been obtained only in animals, the researchers are confident that in the future such strains of probiotics may form the basis of drugs to combat age-related muscle weakness (sarcopenia), metabolic disorders and inflammatory diseases. This is especially true for the elderly, who are losing muscle mass and strength, increasing the risk of falls and a deterioration in their quality of life.

“We have shown that gut microbes directly affect muscles. Now our task is to check whether these effects are repeated in humans and which metabolites play a key role,” the authors note.