New Research May Link Oral Bacteria to Stroke Risk

At CPW Dentistry, we believe that oral health is deeply connected to overall health. A new study set to be presented at the American Stroke Association’s International Stroke Conference 2025 suggests that a common oral bacteria, Streptococcus anginosus, may be linked to a higher risk of stroke and worse outcomes for stroke survivors. You can read the Science Daily article here.

Researchers at Japan’s largest stroke center analyzed the oral and gut bacteria of 250 participants—189 stroke patients and 55 non-stroke individuals of similar age. They found that Streptococcus anginosus was significantly more abundant in stroke patients, both in their saliva and gut. Stroke survivors with higher levels of this bacteria had an increased risk of death and major cardiovascular events over the next two years.

These findings add to growing research connecting oral bacteria to systemic health. The same research team previously linked another bacteria, Streptococcus mutans—a cause of cavities—to an increased risk of brain bleeds. Since both S. anginosus and S. mutans contribute to tooth decay, maintaining good oral hygiene and reducing sugar intake may help manage these bacteria and support overall health.

While this study focused on a Japanese population, researchers emphasize that oral and gut bacteria are influenced by lifestyle, and different bacteria may play a role in stroke risk in other populations. Future research exploring whether these bacterial imbalances can predict stroke risk in individuals before a stroke occurs could open doors to new prevention strategies.

At CPW Dentistry, we’re committed to keeping you informed about the latest research on oral and systemic health. If you have questions about how to optimize your oral care, we’re here to help!

📖 Reference:
Tonomura, S., et al. (2025). Streptococcus anginosus and Stroke Risk: Findings from the National Cerebral and Cardiovascular Center, Osaka, Japan. Presented at the American Stroke Association’s International Stroke Conference, Los Angeles, CA.

The study cited is research abstract and the findings are considered preliminary until published as full manuscripts in a peer-reviewed scientific journal.