Oral bacteria linked to increased risk of stroke

The lead researcher from the National Heart Disease Center in Osaka, notes: "In the future, if a rapid test is developed to identify harmful bacteria in the mouth and intestines, we could use this information to calculate stroke risk.""

Oral bacteria are not only dangerous to teeth but can also lead to stroke.
Oral bacteria are not only dangerous to teeth but can also lead to stroke. Illustration: depositphotos.com


A study in Japan found that increased levels of Streptococcus anginosus – a bacteria common in the mouth and digestive tract – has been found in the guts of stroke survivors. Over a two-year follow-up period, stroke survivors with high levels of this bacteria showed an increased risk of death or a major cardiovascular event. The study was conducted at Japan’s largest stroke center and included 189 stroke survivors compared with 55 non-stroke participants who were undergoing routine medical examinations.

Main findings
Microbiome analysis performed using saliva and stool samples showed that the presence of Streptococcus anginosus in the gut was independently associated with a 20% increased risk of stroke, after controlling for vascular risk factors. In contrast, bacteria such as Anaerostipes hadrus and-Bacteroides plebeus – which are linked to beneficial effects – were associated with a risk reduction of 18% and 14%, respectively. During a two-year follow-up, stroke survivors with high levels of this bacterium experienced an increased rate of mortality and coronary heart disease events, while participants with beneficial bacteria showed no increased risk.

Recommendations and conclusions
Shuichi Tonomura, MD, lead author of the study and a physician in the Department of Neurology at the National Cerebral and Cardiovascular Center in Osaka, notes, “In the future, if a rapid test is developed to identify harmful bacteria in the mouth and gut, we could use this information to calculate stroke risk. Targeting the harmful bacteria could help prevent stroke.” Tonomura also emphasizes the importance of maintaining good oral hygiene, reducing sugar intake, and using a toothpaste designed to prevent tooth decay, which may reduce stroke risk. Louise D. McCullough, MD, PHD, FAHA, adds that studying larger groups of people who have not yet had a stroke but are at risk could deepen our understanding and lead to the development of more effective prevention strategies.

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