Microbes in fermented foods linked to muscle function

A review of scientific studies suggests that microbes in fermented foods may send chemical signals to muscles, rekindling the idea of a gut-to-physical-strength axis. Researchers from the Teagasc Food Research Centre and APC Microbiome Ireland have proposed this connection in a synthesis published on September 25, 2026. The findings primarily concern older individuals, though evidence in humans remains limited.

Exercise and fermented protein improve balance

Three studies have directly measured muscle function. The first involved 48 middle-aged individuals over eight weeks with an exercise program. Participants drank either fermented or non-fermented whey protein twice daily. Those consuming fermented protein showed improved balance, though no significant differences were noted in hand or back strength.

Kefir byproducts show mixed grip strength results

The second study included 53 adults with an average age of 55 over twelve weeks. Their protein drinks contained byproducts from a kefir bacteria, not kefir itself. According to Communications Biology, their grip strength improved, but the results were too close to the placebo effect to rule out chance. Researchers caution against extending these findings to commercial kefir.

Fermented milk reduces muscle soreness in young men

The third study found that fermented milk reduced muscle soreness in 18 young men around 21 years old after intense training. However, the comparison with regular milk was based on a single session. Most of these data concern dairy products, with fermented vegetables like tempeh largely absent from the studies.