A Cleveland Clinic-led study shows a connection between elevated blood levels of TMAO (trimethylamine N-oxide) — a byproduct of gut bacteria digestion of nutrients found in red meat and other animal products — and a higher risk of atrial fibrillation.

The research team, led by Robert Koeth, M.D., Ph.D., analyzed blood samples from more than 5,000 people undergoing heart procedures. The researchers also conducted laboratory studies in cells to better understand how TMAO may influence the heart. They discovered that gut microbe-produced TMAO changes the heart’s electrical environment, increasing susceptibility to abnormal rhythms. Findings were published today in the Journal of Clinical Investigation.

Atrial fibrillation is the most common type of rhythm disorder that begins in your heart’s upper chambers, with at least 2.7 million Americans living with it. Symptoms include fatigue, heart palpitations, trouble breathing and dizziness. Risk factors include high blood pressure, coronary artery disease and having obesity. Medications and procedures such as an ablation, where scar tissue is created to help the electrical system work better, can lower your risk of a stroke.