Streptococcus anginosus in Mouth and Gut Linked to Higher Stroke Risk, Study Reveals

Key Takeaways:

  • A specific oral bacteria, Streptococcus anginosus, is linked to a 20% higher risk of stroke.
  • High levels of this bacteria in the gut may worsen outcomes for stroke survivors.
  • Good oral hygiene and certain “good” gut bacteria could help lower stroke risk.

Brain Stroke

A new study from Japan’s National Center for Brain and Cardiovascular System suggests that the microbes living in your mouth and gut may play a surprising role in stroke risk. Researchers found that people who recently suffered a stroke had significantly higher levels of Streptococcus anginosus—a bacteria linked to tooth decay—in their saliva and intestines compared to healthy adults. Even more striking: Stroke survivors with elevated gut levels of this bacteria faced higher risks of death and cardiovascular complications within two years.

The Gut-Mouth-Brain Connection

The team analyzed saliva and gut bacteria from stroke patients and healthy volunteers, uncovering stark differences in their microbial profiles. While S. anginosus was tied to increased stroke risk, two “friendly” gut bacteria—Anaerostipes hadrus and Bacteroides plebeius—were associated with reduced risk (18% and 14%, respectively). “These findings open doors for new prevention strategies,” says lead researcher Dr. Shuichi Tonomura. “Targeting harmful oral bacteria could be as crucial as managing blood pressure or cholesterol.”

Why Oral Health Matters

S. anginosus thrives in environments with poor oral hygiene, producing acids that erode tooth enamel and cause decay. But its impact may extend far beyond cavities. “This bacteria can trigger inflammation, which damages blood vessels and promotes clot formation—a key driver of strokes,” explains Tonomura. Previous studies have also linked gum disease to systemic inflammation, further supporting the idea that oral health is a window to overall wellness.

Protecting Yourself: Practical Steps

  1. Boost Oral Hygiene: Brush twice daily with fluoride toothpaste and floss to reduce harmful bacteria.
  2. Limit Sugary Foods: Sugar feeds decay-causing bacteria like S. anginosus.
  3. Ask About Probiotics: While research is ongoing, gut-friendly bacteria (e.g., from fermented foods) may help counterbalance harmful strains.
  4. Regular Dental Checkups: Early treatment of cavities or gum disease could lower systemic inflammation.

What This Means For You:

Poor oral health isn’t just about bad breath or cavities—it could signal broader risks. If you’ve had a stroke or have a family history, discuss oral microbiome testing with your doctor. Simple lifestyle changes, like improving dental care and diet, might reduce your risk of future cardiovascular events.

Related Reading:

This study highlights the growing recognition of the oral microbiome’s role in chronic diseases. As researchers expand their work to larger groups, the goal is clear: harnessing “good” bacteria to protect not just smiles, but lives.

FAQs: Oral Bacteria and Stroke Risk Explained

Q: Which bacteria increases stroke risk?
A: Streptococcus anginosus—common in the mouth/gut—raises stroke risk by 20%.

Q: How does Streptococcus anginosus harm health?
A: It promotes tooth decay, inflammation, and blood vessel damage, increasing stroke likelihood.

Q: Can good gut bacteria lower stroke risk?
A: Yes. Anaerostipes hadrus and Bacteroides plebeius reduce risk by up to 18%.

Q: How do I reduce Streptococcus anginosus?
A: Brush with fluoride toothpaste, limit sugar, and visit your dentist regularly.

Q: Why link oral bacteria to stroke?
A: Poor oral hygiene fuels harmful bacteria, triggering inflammation that harms cardiovascular health.

Reference

American Stroke Association. (2025, January 30). A common mouth and gut bacteria may be linked with increased stroke risk. American Stroke Association. https://newsroom.heart.org/news/a-common-mouth-and-gut-bacteria-may-be-linked-with-increased-stroke-risk

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