What if the bacteria in your mouth could help predict your risk of stroke?
A recent study linked a common oral microbe to a roughly 20% higher risk of stroke, and its lead author suggested using an available test to identify harmful bacteria in the mouth and gut. Yet many clinicians remain unaware of this connection as medicine and dentistry often work in separate silos.
What the study found
- Streptococcus anginosus was more abundant in the saliva and gut of stroke patients.
- Stroke survivors who had higher levels of this bacterium faced elevated risks of death and major cardiovascular events over a two-year follow-up.
- Beneficial species, such as Anaerostipes hadrus and Bacteroides plebeius, were associated with lower stroke risk.
- The analysis included 250 people—189 recent stroke patients and 55 controls—using samples from Japan’s largest stroke center.
- Researchers adjusted for vascular risk factors like hypertension and diabetes, strengthening the link between Streptococcus anginosus and stroke outcomes.
- Patients were followed for two years to track survival and recurrent cardiovascular events.
In short: this study strengthens the idea that the oral microbiome is relevant to stroke prevention, not just dental care.
Why this matters beyond stroke
- Brain health: Some oral bacteria can promote inflammation that contributes to cognitive decline and memory issues.
- Heart health: Oral pathogens and gum disease bacteria can enter the bloodstream, raising cardiovascular risk.
- Gut-brain connection: Changes in the oral microbiome can influence gut microbes, fueling systemic inflammation, mood changes, and digestive problems.
Put simply, oral health is closely tied to overall health. Protecting your oral microbiome could help preserve cognitive and cardiovascular health over time.
The study’s lead investigator, Shuichi Tonomura, M.D., suggested that a quick test to detect harmful oral and gut bacteria could be used to help estimate stroke risk and guide preventive strategies. That test already exists, but it is not yet widely used by clinicians.
Medicine and dentistry often treat symptoms in isolation: dentists focus on gums and teeth, while physicians focus on organs like the heart and brain. Integrating oral microbiome testing and communication between providers could close that gap and improve prevention.
Test your oral microbiome
Most providers aren’t routinely testing the oral microbiome, but at-home or clinic-based tests can provide actionable information. For many people, a test costing around $100 can reveal which bacteria are present and help guide targeted prevention. While testing is only one tool, it can inform changes in oral care and lifestyle that reduce risk.
Simple, evidence-based changes in oral care—improved brushing and flossing, treatment for gum disease, and attention to diet—can meaningfully affect the oral microbiome and, by extension, overall health. Clinicians and patients alike should treat the mouth as an integral part of the body, not a separate system.
If you’re curious about your levels, consider discussing oral microbiome testing with your dentist or primary care provider. Testing can be one step toward personalized prevention and a more holistic approach to health.
I welcome feedback—let me know what you think of this update.
P.S. I also maintain a curated list of oral-health-friendly products, including toothpaste and probiotics that support a healthy oral microbiome. Consider choosing products that promote balance rather than simply masking symptoms.