Researchers in Cleveland have found a second bacteria in the
human digestive system that converts meat into substances that block arteries.
The two discoveries by the same team of researchers hold out
hope that the formation of these harmful substances can be blocked.
The Cleveland Clinic researchers first
discovered that microbes in the human digestive tract turn L-carnitine, a
nutrient abundant in red meat, into trimethylamine-N-oxide (TMAO), a metabolite
that promotes hardening of the arteries.
Now, they have identified a second metabolite,
called gamma-butyrobetaine, that they say is generated to an even greater
extent by gut bacteria after L-carnitine is ingested, and it too contributes to
atherosclerosis.
The new findings, published in the journal Cell Metabolism, show
gamma-butyrobetaine can itself be converted into TMAO.
The researchers also discovered the bacteria
that produce gamma-butyrobetaine from L-carnitine are different from the
bacterial species that produce trimethylamine from L-carnitine.
The discovery that metabolism of L-carnitine
involves two different gut microbial pathways, as well as different types of
bacteria, could lead to new strategies for preventing atherosclerosis, the
researchers said.
For example, therapies could be developed to
inhibit various bacterial enzymes or to shift gut bacterial composition with
probiotics and other treatments.
"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," said Dr. Stanley Hazen, of Lerner Research Institute and the
Miller Family Heart and Vascular Institute at Cleveland Clinic, who led the
research.
