There is growing evidence of a complex oral-gut-brain axis linking mouth and gut microbiomes with the central nervous system, and bacteriocin-based approaches such as nisin can modulate this axis by restoring microbial balance, reducing inflammation, and reducing brain amyloid/tau accumulation.
Periodontal disease is associated with increased oral pathogen presence in diseased tissues throughout the human body.
Experimental periodontal infection induces dysbiosis that is linked to activation of inflammatory pathways promoting diseased phenotypes.
Oral and gut dysbiosis can trigger oral and systemic inflammation and neuroinflammation, contributing to diseases such as Alzheimer's disease and Parkinson's disease.
The probiotic bacteriocin nisin was found to restore microbial balance, reduce inflammation, inhibit end-organ pathology, prevent periodontal bone loss, and reduce brain amyloid/tau accumulation and cytokine expression.
The oral microbiome modulates human health and disease through mechanistic pathways connecting the mouth, gut, and brain.
Future probiotic or antimicrobial strategies aimed at ameliorating neuroinflammatory and metabolic diseases via microbiome-targeted therapy hold clinical promise.
This research suggests that the health of the mouth is deeply connected to the health of both the gut and the brain through what scientists are calling the 'oral-gut-brain axis.' When the balance of bacteria in the mouth is disrupted — a condition known as dysbiosis, often caused by periodontal (gum) disease — it can set off a chain reaction of inflammation that travels through the gut and ultimately affects the brain. The paper reviewed evidence from both human studies and animal experiments showing that oral pathogens can be found in diseased tissues throughout the body, and that this microbial imbalance may contribute to serious neurological conditions like Alzheimer's disease and Parkinson's disease. One of the more concrete findings highlighted in this review is that a naturally occurring antimicrobial compound called nisin — classified as a bacteriocin and derived from certain bacteria — shows promise as a therapeutic tool for targeting this axis. In experimental models, nisin was shown to restore microbial balance, reduce inflammation, prevent gum-related bone loss, and reduce the accumulation of amyloid and tau proteins in the brain, which are characteristic features of Alzheimer's disease. These effects were observed at multiple points along the oral-gut-brain pathway, suggesting nisin may act systemically rather than just locally in the mouth. This research suggests that treating gum disease and restoring a healthy oral microbiome could have far-reaching effects on brain and systemic health, and that bacteriocin-based therapies like nisin represent a promising new direction for preventing or managing neuroinflammatory and metabolic diseases. While these findings are encouraging, much of the supporting evidence comes from animal models and preclinical studies, and further human clinical trials would be needed to confirm these effects in people.
Y. Hernandez-Kapila, D. Weisenberger. (2026). Of mice and men-The emerging oral-gut-brain axis of health and disease.. Periodontology 2000. https://doi.org/10.1111/prd.70064