By Lisa Marshall

Principal investigators
Vienna Brunt; Doug Seals

National Institutes of Health (NIH)

Arteries in human body graphicA compound produced in the gut when we eat red meat plays a key role in boosting heart disease risk with age, suggests research published by integrative physiology Professor Doug Seals.

Eat a steak and your gut bacteria break it down, churning out a metabolic byproduct called trimethylamine, which the liver converts to trimethylamine N-oxide (TMAO). People with higher blood levels of TMAO are known to be twice as likely to have a heart attack and tend to die earlier.

But scientists haven’t known why. 

When the researchers studied 101 older adults and 22 young adults, they found that TMAO levels rise with age, and adults with higher blood levels had worse artery function and more vessel damage. When fed TMAO directly, young mice swiftly began to look like old mice in terms of vessel health.

Even a young vegan produces some TMAO. But over time, the study suggests, eating excess animal products may prompt you to make too much, exacerbating vascular decline.