Previous studies show that the balance of microbiomes in the oral cavity and intestines can affect the risk of stroke. This is reported by scientists who will present their findings at the American Stroke Association's International Stroke Conference 2025, UNN writes with reference to Eatingwell.
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There are several microbiomes in the human body, including the gut and oral microbiomes, which are connected and influence each other. Researchers have found a link between the gut microbiome and chronic inflammation, which can cause chronic diseases such as heart disease, diabetes, and cancer.
According to previous studies, people who have suffered a stroke also have microbiome imbalances. This prompted the researchers to consider other factors that can trigger both the stroke itself and contribute to how well people recover from it.
The microbiome is reportedly loaded with trillions of both beneficial and potentially harmful bacteria. This set of bacteria and other microorganisms in the gut is called the intestinal microbiota, and in the mouth is called the oral microbiota. Because it is likely not possible to completely eliminate all potentially harmful organisms, the goal is to maintain an optimal number of beneficial bacteria that exceeds the number of harmful bacteria.
A previous study found a link between the bacterium that causes tooth decay, called Streptococcus mutans, and an increased risk of cerebral hemorrhage, which causes stroke,
In this latest study, researchers examined another harmful bacterium called Streptococcus anginosus. This strain of bacteria has been linked to conditions such as oral abscesses and even abscesses in the frontal lobes of the brain. Researchers have also pointed to Streptococcus anginosus as a cause of tooth decay because it can destroy tooth enamel.
A total of 250 Japanese people took part in this study, with an average age of 70 years. About 40% of them were women. The 250 participants were divided into two groups - a test group and a control group. The researchers compared the oral and gut microbiomes of 200 participants who had had a stroke within the last seven days (test group) with the microbiomes of 50 people without a history of stroke (control group). Although they did not have a history of stroke, the control group may have had other medical problems, including high blood pressure, diabetes, or high cholesterol, all of which are risk factors for stroke.
The researchers found that Streptococcus anginosus was significantly more prevalent in the saliva and intestines of people who had stroke than in the control group.