2025 International Stroke Conference: Having this bacteria in your mouth increases your risk of stroke by 20%

From February 5 to 7, 2025, the highly anticipated 2025 International Stroke Conference (ISC) was held in Los Angeles, USA. The International Stroke Conference (ISC) is a global academic conference hosted by the American Heart Association/American Stroke Association (AHA/ASA), focusing on the research, prevention, treatment and rehabilitation of stroke. It is the largest conference dedicated to the research and treatment of cerebrovascular diseases worldwide. This conference brought together top experts in stroke research, senior clinicians and health policy makers from all over the world to discuss the latest research results and future development directions in the field of stroke.

Dr. Shuichi Tonomura from the Department of Neurology at the National Brain and Cardiovascular Center in Osaka, Japan, published a study that found that people with a type of bacteria called Streptococcus anginosus in their mouths and intestines have a stroke risk that is about 20% higher than others.

There are a large number of bacteria in our mouths and intestines, most of which are beneficial and can promote digestion and prevent diseases. If the proportion of harmful bacteria is out of balance, it will cause various diseases, including diabetes and heart disease. The research team extracted saliva and intestinal flora samples from patients with stroke and compared them with the general population. It was found that the content of Streptococcus anginosus in samples from acute stroke patients was significantly higher than that in the control group, while high levels of Streptococcus mutans were associated with a high incidence of intracerebral hemorrhage.

Controlling for other vascular risk factors, the comparison showed that abnormalities in Streptococcus anginosus in the oral and intestinal tract increased the risk of stroke by 20%, while the two beneficial bacteria, Anaerostipes hadrus and Bacteroides plebeius, which are common in the Japanese population, reduced the risk by 18% and 14%, respectively. During the two-year follow-up period, patients with streptococci had significantly higher risks of gastrointestinal bleeding and cardiovascular events.

Who has streptococci and mutans in their mouths? Do you know by testing? In fact, both harmful bacteria can produce acids that decompose tooth enamel and cause tooth decay; conversely, people with tooth decay are likely to have higher levels of harmful bacteria in their mouths, which highlights the importance of preventing tooth decay and the need to maintain good oral hygiene habits, such as reducing sugar intake and using antibacterial toothpaste.

Interestingly, this conference also has a report on oral health that echoes it - using dental floss once a week to prevent infection and inflammation can reduce the risk of ischemic stroke by 22%, and the risk of cardioembolic stroke by 44%.

Experts said that this study verified the key role of streptococci in the onset of stroke and the long-term risk of stroke, providing a practical preventive measure for the long-term management of the disease. Of course, the oral and intestinal microbiota are greatly affected by lifestyle and geographical factors, and other regions such as Europe and the United States need to make corresponding adjustments based on the characteristics of the local population's microbiota.