American researchers explain why red meat damages heart

WASHINGTON: Gut bacteria can turn a nutrient found in red meat into metabolites that increase the risk of developing heart disease, according to a US study out Tuesday that may lead to new strategies for safeguarding individuals' cardiovascular health.

"The findings identify the pathways and participants involved more clearly, and help identify targets for therapies for interventions to block or prevent heart disease development," said Stanley Hazen of Cleveland Clinic, who led the study.

"While this is into the future, the present studies may help us to develop an intervention that allows one to 'have their steak and eat it too' with less concern for developing heart disease," Hazen said.

Previous research led by Hazen revealed a pathway by which red meat can promote atherosclerosis, or hardening of the arteries.

Essentially, bacteria in the gut convert L-carnitine, a nutrient abundant in red meat, into a compound called trimethylamine, which in turn changes to a metabolite named trimethylamine-N-oxide (TMAO).

The new study, published in the U.S. journal Cell Metabolism, identified a second metabolite, called gamma-butyrobetaine, which is produced at a rate 1,000-fold higher than TMAO formation.

Both metabolites promote atherosclerosis, which may lead to heart attacks, heart disease and stroke.

The study also showed two different types of gut bacteria are responsible for metabolizing L-carnitine into gamma-butyrobetaine and TMAO.

"The discovery ... suggests new targets for preventing atherosclerosis, for example, by inhibiting various bacterial enzymes or shifting gut bacterial composition with probiotics and other treatments," the researchers said in a statement.