Heart disease remains the world’s leading cause of death, claiming nearly 20 million lives each year. While genetics, lifestyle and environment are well-known risk factors, scientists are turning their attention to another influence inside the body: the trillions of bacteria that live in the gut.
A new study published in mSystems by researchers at Sungkyunkwan University in Seoul adds to the growing evidence that gut microbes may help shape the development and severity of coronary artery disease (CAD). By taking a closer look at what these bacteria do, not just which ones are present, the team uncovered microbial pathways tied to inflammation and metabolic imbalance, two hallmarks of heart disease.
“We’ve gone beyond identifying ‘which bacteria live there’ to uncovering what they actually do in the heart-gut connection,” said Han-Na Kim, Ph.D., genomicist at the Samsung Advanced Institute for Health Sciences and Technology at Sungkyunkwan University, who led the study.
The researchers compared fecal samples from 14 people with CAD to those from 28 healthy individuals, using a technique called metagenomic sequencing to reconstruct the full genetic profiles of the microbes living in each gut. The analysis revealed 15 bacterial species associated with CAD, along with specific pathways that may connect gut activity to heart health.
“Our high-resolution metagenomic map shows a dramatic functional shift toward inflammation and metabolic imbalance, a loss of protective short-chain fatty acid producers, such as Faecalibacterium prausnitzii, and an overactivation of pathways, such as the urea cycle, linked to disease severity,” Kim said.
The findings also challenge the notion that “good” and “bad” bacteria can be easily categorized. Some microbes typically considered beneficial, like Akkermansia muciniphila and F. prausnitzii, appeared to behave differently in people with heart disease.
“Microbes usually categorized as being beneficial to human health … can have different functional roles depending on whether they came from healthy or diseased guts,” Kim explained.
The study highlights the complexity of the gut-heart relationship. In one example, the bacterial family Lachnospiraceae showed mixed patterns: some species declined in people with CAD, while others increased. Kim described them as “the Dr. Jekyll and Mr. Hyde of the gut,” underscoring how context can determine whether certain microbes protect or harm the host.
The next step, Kim said, is to integrate microbial data with genetics and metabolism to map more precise biological pathways. In the long term, researchers hope this work could lead to personalized prevention strategies that use the microbiome as both a marker and a target for intervention.
“Prevention is the most promising frontier for reducing the global burden of heart disease,” Kim said.
Future applications could include stool-based screening tools or nutritional approaches designed to restore helpful bacteria and block harmful pathways.
The study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean Government.