Link found between common mouth bacteria and heart disease


Coronary heart disease (CHD) is responsible for around one-third of all deaths worldwide. A new longitudinal study has investigated the link between a commonly occurring oral bacteria and CHD, improving our understanding of how infection affects the development of heart disease.

CHD is the most common form of heart disease. Over time, plaque collects on the walls of the arteries that supply blood to the heart (atherosclerosis), causing an obstruction to blood flow. The obstruction causes symptoms of chest pain (angina), breathing difficulties and chest tightness, and pain in the arms or shoulders. If plaque completely blocks an artery, it can result in a heart attack.

CHD is caused by a combination of genetic, environmental, and demographic factors. The main risk factors are smoking, diabetes, high blood fats (hyperlipidemia) and high blood pressure (hypertension). Age is also an important risk factor, and men are more likely to develop CHD than women.

Previous studies have also identified a link between the development of arterial plaque and the body’s inflammatory response. These studies led to renewed interest in the role bacteria, viruses, and other microorganisms play in heart disease.

“Although enormous progress has been made in understanding how coronary heart disease develops, our understanding of how infections, inflammation, and genetic risk factors contribute is still incomplete,” said Flavia Hodel, lead author of the current study.

The study followed 3,459 participants and monitored their heart health over 12 years. Data were collected on the participants’ blood C-reactive protein (CRP) levels, a measure of inflammation. Participants were also tested for 22 human pathogens, including 15 viruses, six bacteria, and one parasite.

One of the bacteria tested for was Fusobacterium nucleatum, a bacterium that is prevalent in humans. It is a very common mouth bacteria that can lead to gum inflammation (gingivitis) and gum infection (periodontitis). Previous studies have also noted its potential to spread to the gut and to the female genital tract, causing inflammation and disease.

Based on the data collected, the present study demonstrated a link between previous or current infection with F. nucleatum and a slightly increased risk of CHD. The researchers hypothesize that the bacterium causes harm in two ways. First, in cases of oral infection, it causes a generalized inflammatory response in the body. Second, it migrates from the mouth and attaches itself directly to the walls of the coronary arteries, encouraging plaque growth.

“Our study adds to growing evidence that inflammation triggered by infections may contribute to the development of coronary heart disease and increase the risk of a heart attack,” said Jacques Fellay, a professor at the School of Life Sciences of EPFL, Switzerland and senior author on the study.

Future studies are needed to confirm the link, but if confirmed, it may open the door to simple antibiotic therapy as a treatment option where the cause of CHD is infection.

“Our results may lead to new ways of identifying high-risk individuals or lay the groundwork for studies of preventive interventions that treat F. nucleatum infection to protect the heart,” Fellay said.

The study was published in eLife.

New Atlas, 15 February 2023