A new study exploring the link between cardiovascular disease and a gut bacteria metabolite known as trimethylamine-N-oxide (TMAO) has reported that “higher TMAO levels predict higher future risk of death from heart failure, independent of other clinically used blood tests or risk factors.” W.H. Wilson Tang, et al., “Prognostic Value of Elevated Levels of Intestinal Microbe-Generated Metabolite Trimethylamine-N-Oxide in Patients With Heart Failure: Refining the Gut Hypothesis,” Journal of the American College of Cardiology, November 2014. Led by the Lerner Research Institute’s Department of Cellular and Molecular Medicine Chair Stanley Hazen, a Cleveland Clinic team followed 720 patients with stable heart failure over a five-year follow-up period, finding that “higher plasma TMAO levels were associated with a 3.4-fold increased mortality risk.” They also noted that patients with elevated levels of TMAO and B-type natriuretic peptide “had more than a 50 percent mortality rate over [five] years.”

This latest study builds on work suggesting that gut bacteria produce TMAO during digestion of L-carnitine and lecithin, dietary nutrients found in red meat, egg yolks, liver, and some energy drinks. In addition, Hazen and his team previously identified “a relationship between TMAO levels and future cardiac events like heart attack, stroke, and death—even in those with no prior evidence of cardiac disease risk,” a finding the American Heart Association named among 2013’s top ten advances in heart disease science.

“I am excited that these studies suggest TMAO testing may not only help identify those patients at greatest risk and for whom more aggressive monitoring is needed, but also that TMAO testing may help to tailor dietary efforts to the individual in the hopes of reducing future risks among those high-risk subjects,” Hazen was quoted as saying. Additional details about previous TMAO studies appear in Issues 479 and 481 of this Update. See Cleveland Clinic News Release, October 27, 2014.