Can your gut microbiome influence your risk of heart disease?

Your gut microbiome produces metabolic by-products that reach your heart and blood vessels through the bloodstream. One well-known culprit is TMAO, a compound formed when gut bacteria process certain nutrients (from meat and eggs). Short-chain fatty acids and bile acids also play a role. Through these pathways, the gut microbiome can contribute to arterial hardening, high blood pressure, heart failure and heart attacks. Multiple reviews and observational studies confirm this relationship, although direct causality in humans has not yet been fully established.

A concrete example is the compound PAGln, formed when gut bacteria convert the amino acid phenylalanine (from protein-rich foods). In a cohort of roughly 4,000 people, higher PAGln levels were found to be associated with more heart attacks, strokes and deaths. In animal models, PAGln demonstrably increased the tendency of platelets to clump together, which raises the risk of a blood clot. Note: the lead researcher behind this work has financial interests in related diagnostics, which is a factor to keep in mind when interpreting the findings.

A disrupted balance in the gut microbiome, with too few protective and too many harmful bacteria, is linked in observational research to known risk factors such as arterial hardening, high blood pressure and excess weight. Whether that disruption is the cause of the higher risk, or rather a consequence of an unhealthy lifestyle, has not yet been clarified. Certain beneficial bacterial species, such as Lactobacillus and Akkermansia, appear to be able to lower cholesterol to some extent, but clinical results with probiotics are mixed and the evidence is still limited.

A large Chinese study with more than 10,000 participants found that people with a 'younger' gut microbiome had a lower cardiovascular risk, even if they were dealing with excess weight or high blood sugar. In people with metabolic problems combined with an 'older' gut microbiome, the risk was up to more than twice as high. This is an observational study in a specific population, so the finding does not automatically apply to everyone.

Treatments that influence the gut microbiome, such as probiotics, prebiotics, fecal transplantation and antibiotics, are being investigated as a possible approach to cardiovascular disease. However, this remains largely experimental territory. Fecal transplantation and broad antibiotic courses carry real risks and are not recommended outside clinical trials for this purpose.