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This Brain Health Clue May Be Hiding In Your Mouth
Your mouth is home to a whole community of bacteria, and some of these microbes do more than influence your breath or gum health.
They help process dietary nitrate (a compound found naturally in vegetables like leafy greens and beets), which the body uses to make nitric oxide, a molecule that supports healthy blood flow. Could these bacteria also be connected to brain health?
A recent study explored this question by comparing tongue bacteria and cognitive performance in younger and older adults.
About the study
Researchers recruited 60 healthy adults from Exeter, UK, and Brussels, Belgium. Each location included 15 younger and 15 older participants.
Participants completed cognitive tests measuring memory, attention, reasoning, and reaction time. Researchers also measured blood pressure, collected blood and saliva samples, and used genetic sequencing to analyze bacteria from tongue swabs.
The team was particularly interested in bacteria that help convert dietary nitrate into nitrite, which the body can use to produce nitric oxide.
Certain mouth bacteria were linked to cognitive performance
The researchers found differences in the oral bacteria of younger and older adults, as well as associations between certain bacteria and cognitive test results.
- Older adults had higher levels of bacteria associated with gum disease: They had more Treponema and Tannerella, two bacterial groups linked to periodontal disease.
- Younger adults had more of a nitrate-processing bacterium: They had higher levels of Neisseria flavescens, which helps process dietary nitrate.
- Another nitrate-processing bacterium was associated with cognitive performance: Higher levels of Haemophilus parainfluenzae were linked to faster reaction times and accuracy on certain tests.
Age was the most consistent predictor of cognitive performance. In both countries, older participants generally had lower overall scores, slower reaction times, and lower accuracy on tests of memory, attention, and processing speed.
The bacteria findings were more mixed. Levels of H. parainfluenzae didn't differ between younger and older adults, so the study doesn't tie it to either age group, and its links to cognition varied by country and by task. The findings point to a possible connection worth investigating, not evidence that nitrate-processing bacteria protect the brain.
How your mouth could be connected to brain aging
One possible explanation involves nitric oxide, which helps blood vessels relax and supports blood flow—an important factor in brain health.
Because oral bacteria help the body process dietary nitrate to produce this molecule, changes in the oral microbiome could potentially influence this pathway. Nitric oxide availability can also decline with age.
Other research has linked gum-disease-associated bacteria to inflammation and explored connections between periodontal bacteria and dementia risk.
However, this was a small study, and it cannot show that oral bacteria cause cognitive decline. Researchers also didn't test whether changing the oral microbiome improved brain function, so larger studies are needed.
Everyday habits that support a healthier mouth
There's no established way to change your oral microbiome specifically for better brain health, but a few habits support oral health and the processes researchers are investigating.
- Eat nitrate-rich vegetables: Leafy greens and beets provide dietary nitrate, which oral bacteria help process.
- Keep up with oral hygiene: Brush, floss, and attend regular dental checkups to help protect your gums.
- Be thoughtful about antibacterial mouthwash: Some formulas may reduce nitrate-processing bacteria. Researchers are also exploring whether mouthwash timing affects blood sugar.
The takeaway
Your oral microbiome may offer clues about brain health, but we're still figuring out what those clues mean.
For now, there's no need to chase specific bacteria. Keep your gums healthy, eat your greens, and let the research catch up.