Study reveals 22pc higher stroke risk related to lazy brushing

Neglecting to brush your teeth long-term doesn't just cause cavities – it may also increase the risk of various diseases. Research has found that poor oral hygiene not only can trigger various illnesses but also increases stroke risk by 22 percent. In fact, simply maintaining a specific daily brushing frequency can achieve the dual benefits of protecting cardiovascular health and stabilizing blood sugar.

Intensive care doctor Wong Hin stated in a Facebook post that most people generally believe arterial hardening is only related to high cholesterol or a high-fat diet. However, according to multiple studies confirmed, incomplete teeth cleaning can lead to blocked blood vessels and increase the risk of various diseases.

What Are the Consequences of Not Brushing Teeth Properly?

1. Increases Risk of Arterial Plaque Formation
According to research published in the Journal of the American Heart Association, a research team from Finland's Tampere University analyzed over 200 arterial plaque samples and found:

• Bacterial DNA was detected in 65 percent of the plaque samples, with a staggering 42 percent of these bacteria originating from oral streptococci.
• These bacteria normally reside in gum crevices. When gum bleeding or inflammation occurs, they seize the opportunity to invade the bloodstream and adhere to the inner walls of blood vessels.
• They then form a protective biofilm, allowing them to evade detection by the immune system, lie dormant long-term, and continuously release inflammatory factors, gradually eroding the vascular tissue structure.
• When the body faces stress, a cold, or a weakened immune system, these dormant bacteria can suddenly activate, triggering a severe local inflammatory response, leading to arterial plaque rupture and thrombus (clot) formation. This is the key mechanism behind acute myocardial infarction (heart attack).
• The researchers further explained that these bacteria activate the TLR2 receptor signaling pathway, inducing an excessive immune response, which becomes an important driving factor for the continuous worsening of atherosclerosis.

2. Increases Cardiovascular Disease Risk
Wong stated that multiple long-term tracking studies show that low brushing frequency—i.e., once a day or less—is associated with an increased incidence of cardiovascular disease. Citing a Japanese study involving over 71,000 people as an example, it found that among groups who brushed once a day or less:

• The overall stroke risk increased by 22 percent.
• For patients already diagnosed with coronary heart disease, combined with low brushing habits, the risk of major cardiovascular events increased even more significantly, by up to 70 percent.

How Many Times a Day Should You Brush to Protect the Heart and Lower Blood Sugar?

Wong pointed out that maintaining good brushing habits is the best preventive prescription recommended by cardiologists. Besides reducing the chance of oral bacteria entering the bloodstream and blocking their pathway into the circulation, multiple evidence-based studies have found it has multiple effects: reducing chronic inflammation, delaying vascular hardening, stabilizing blood sugar levels, and maintaining metabolic function.

1. Protects Cardiovascular Health

• Large-scale studies show that people who brush their teeth three times a day have a significantly lower incidence of cardiovascular disease, with the risk reduction showing a clear dose-response relationship.
• Frequent brushing (≥3 times/day) can effectively reduce the probability of major cardiovascular events like atrial fibrillation, coronary heart disease, and stroke, with an average risk reduction of about 10 to 15 percent.

2. Prevents Diabetes

• A 2023 South Korean study published in Diabetes Care analyzed the association between brushing frequency and diabetes risk across different age groups. The main findings were:
  • Younger population (aged 51 and below): Due to lower baseline inflammatory load and higher stability of oral flora, brushing three times daily can more effectively remove pathogenic bacteria, reducing the level of systemic chronic inflammation, leading to a 14 percent reduction in diabetes risk.
  • Older population (aged 52 and above): Although still protective, the risk reduction diminishes to 7 percent due to accumulated long-term chronic inflammation, higher rates of periodontal disease and tooth loss, plus age-related immune decline and pre-existing metabolic abnormalities.

Wong stated that increasing brushing frequency reduces the entry of pathogens like oral streptococci into the bloodstream, directly lowering the detection rate of bacterial DNA in arterial plaques, thereby alleviating systemic inflammatory response. This mechanism is particularly significant in younger populations. Overall, improving oral hygiene does have benefits for diabetes prevention across all age groups, but the effect is more pronounced the younger the person is.

Furthermore, oral bacteria entering the bloodstream can affect insulin sensitivity and stimulate an increase in inflammatory cytokines, ultimately leading to blood sugar metabolism dysfunction. Therefore, maintaining oral cleanliness is an important foundation for building a low-inflammation constitution.

Expert Profile: Huang Xuan
Associate Professor, Gastroenterology and Hepatology, Linkou Chang Gung Memorial Hospital, Taiwan. Specializes in inflammatory bowel diseases such as Crohn's disease and ulcerative colitis.