Tempted to skip the floss? A new study from Hiroshima University warns that neglecting oral hygiene could have serious consequences for your heart.
Researchers found that the gum disease bacterium Porphyromonas gingivalis (P. gingivalis) can enter the bloodstream, infiltrate the heart, and promote scar tissue buildup — a process called fibrosis — which distorts heart structure, disrupts electrical signals, and increases the risk of atrial fibrillation (AFib).
Periodontitis, a common form of gum disease, has long been linked to cardiovascular issues. Meta-analyses suggest a 30% higher risk of AFib in people with gum disease, a serious heart rhythm disorder that can cause stroke, heart failure, and other complications. AFib cases worldwide surged from 33.5 million in 2010 to around 60 million by 2019.
While inflammation was thought to be the main culprit, this study, published in Circulation, offers the first clear evidence that P. gingivalis can move from the gums to the heart’s left atrium in both animals and humans, providing a possible microbial link between gum disease and AFib.
In experiments, researchers infected mice with a highly aggressive P. gingivalis strain. By week 18, infected mice were six times more likely to develop abnormal heart rhythms compared to controls. Scarring in the heart’s left atrium was also greater in infected mice, and the bacterium’s DNA was found in heart tissue.
The human arm of the study analyzed heart tissue from 68 AFib patients undergoing surgery. P. gingivalis was detected in the left atrium, with higher levels in patients who had severe gum disease.
- gingivalis is known for its stealth: it can hide inside host cells, evade immune defenses, and cause chronic low-level inflammation. In the study, infected mice had elevated galectin-3 (a fibrosis biomarker) and increased Tgfb1 gene expression linked to inflammation and scarring.
The findings suggest that regular brushing, flossing, and dental checkups might help protect against AFib by preventing P. gingivalis from entering the bloodstream. The researchers are now fostering collaboration between medical and dental professionals in Hiroshima to improve cardiovascular prevention.
“Periodontal treatment, which can block the gateway of P. gingivalis translocation, may play an important role in AFib prevention and treatment,” said lead author Shunsuke Miyauchi.
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The study is published in Circulation.
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