Probiotics and dietary changes: could they help protect brain health as we age?

A new review in Nutrition Research examined probiotics, prebiotics, dietary interventions and fecal microbial transfer (FMT) in more than 4,200 adults aged 45 and older and concluded that modulating the gut microbiome might help older adults with early cognitive decline; the authors say more research is needed.

A recent review published in Nutrition Research examined whether probiotics, prebiotics, dietary changes and fecal microbial transfer (FMT) could help protect brain health in older adults. The authors report that modulating the gut microbiome might help older adults with early cognitive decline improve thinking skills. They point to possible mechanisms including reduced neuroinflammation, altered neurotransmitter signaling, and increased microbial metabolites such as short‑chain fatty acids (SCFAs). The review’s authors and outside experts note the field is still young and that further study is needed. Key findings: - The review included 15 studies from 10 countries with more than 4,200 participants aged 45 or older. - The authors reported that dietary interventions can remodel the gut microbiome, increase SCFA production, stabilize neurotransmitter networks, and reduce inflammation in the brain. - Probiotics and synbiotics were associated in some studies with improved verbal fluency and executive function, and with increased microbiome diversity. - FMT was described as "preliminary but striking" in the review; one included study of people with Alzheimer's disease found a faster change in the gut microbiome after FMT and measured improvements in cognitive performance, though the evidence is limited. - Most studies in the review were small and short-term, and the authors called for more research to confirm effects and identify which strains or approaches might be effective. - The article notes that commercially available probiotics are generally chosen for safety rather than proven brain benefits, that FMT is not widely accessible, and that an expert quoted in the piece said many people consume insufficient fiber and discussed aiming for a diverse plant intake to support gut microbes. Summary: The review suggests that microbiome modulation—through probiotics, synbiotics, dietary changes or FMT—may support cognitive function and reduce neuroinflammation, but the evidence is preliminary. The studies to date are mostly small and short-term, and the authors call for further research to clarify which interventions, strains or doses might provide benefit.