Figure 1.

The oral–gut–brain axis. The interactions between the oral cavity, the gut, and the brain through the microbiota. The oral microbiota also interacts directly with the brain as well as several other organs in the body through the oral–brain or oral–body axes. Poor oral hygiene and untreated oral diseases can cause harmful oral microbiota to reach the gut and or the brain, leading to potential deleterious systemic effects. Maintaining oral hygiene by good practices and dietary interventions can help maintain gut health and brain health, and facilitate healthy aging.