Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial

Randomized controlled trial in older adults aged 60 years or older from the TwinsUK cohort, using a twin-pair 1:1 design with one twin allocated to prebiotic and the matched twin to placebo. The sample was largely female and selected for low dietary protein intake; the intervention was delivered remotely over 12 weeks.

The active regimen was a prebiotic sachet, Darmocare Pre, at 7.5 g/day for 12 weeks, taken once daily and mixed in water or another drink. The prebiotic provided inulin (minimum 3375 mg) and fructo-oligosaccharides (minimum 3488 mg). All participants also received 3.32 g BCAA protein powder per sachet; the comparator sachet contained 7.5 g maltodextrin and was identical in appearance.

The prebiotic improved cognition versus placebo, but it did not improve the primary muscle outcome of chair rise time or other muscle-strength outcomes over 12 weeks. Chair rise time changed from 10.38 to 9.49 seconds in the prebiotic group versus 10.24 to 9.12 seconds in placebo, with no treatment effect (β = 0.579; 95% CI -1.080 to 2.239; p = 0.494). Cognition factor score improved more with prebiotic than placebo (β = -0.482; 95% CI -0.813 to -0.141; p = 0.014). The intervention also increased Bifidobacterium and microbiome features correlated with cognition and muscle-related measures.

The active arm was small, with only 36 participants receiving the prebiotic, and follow-up was short at 12 weeks. The cohort was predominantly female twins from the United Kingdom, which limits generalizability. Several cognitive and muscle-related outcomes were secondary or mixed, and the study relied on a remotely delivered design with self-reported activity and dietary measures.