Could the Gut Microbiome Reflect Heart Health?

A new human study published in Nature Cardiovascular Research explored how the gut microbiome differs in people living with chronic systolic heart failure. The research adds to growing evidence that the gut may interact with body systems far beyond digestion, including the immune and cardiovascular systems.

Researchers studied 59 adults with chronic systolic heart failure caused by nonischemic cardiomyopathy and compared them with 50 healthy participants. Stool samples were analyzed using whole-genome sequencing to examine gut microbial composition and function. The researchers also measured blood metabolites, immune markers, and other biological signals. Twenty-six people with heart failure returned for another assessment after about six months, allowing the team to examine changes over time.

The study found that people with heart failure had lower gut microbial diversity than healthy participants. Several bacterial groups, including Bifidobacterium, were less abundant. The researchers also found lower microbial pathways linked to the production of short-chain fatty acids, including butyrate. These compounds are produced when certain gut microbes ferment dietary components such as fiber.

One finding that drew attention was indole-3-propionic acid (IPA), a compound that can be produced through microbial processing of tryptophan. Blood levels of IPA were lower in participants with heart failure and were associated with milder disease measures. Higher levels of Bifidobacterium were also associated with clinical improvement during follow-up.

However, the study does not prove that gut bacteria cause heart failure or that increasing specific bacteria will improve heart health. The researchers observed associations, and the heart-failure group was relatively small. Differences in medications, diet, and other health factors may also influence the microbiome. The authors note that it remains unclear whether microbiome changes contribute to disease progression or partly reflect the effects of heart failure itself.

This human study shows that chronic heart failure is associated with measurable changes in the gut microbiome, including differences in bacterial diversity, microbial functions, and gut-derived metabolites. It offers another look at the gut–heart connection and provides potential areas for future research.