A new line of preliminary research has turned up a novel pathway linking atherosclerosis to red meat and a common supplement contained in energy drinks. If the research is upheld, the findings may have important implications for dietary recommendations and our understanding of atherosclerosis. The research also provides a quite surprising example of the previously unsuspected health effects of bacteria in the intestine.
Published online in Nature Medicine, the new studies suggest a possible major role in atherosclerosis for carnitine, which is commonly added to energy drinks and is found naturally in high concentrations in red meat. The new theory combines several lines of evidence from studies in both animals and humans.
Led by Stanley Hazen, researchers at the Cleveland Clinic and elsewhere found that digestive tract bacteria metabolize carnitine into trimethylamine-N-oxide (TMAO), which has previously been linked to atherosclerosis in mice, though the exact mechanism is still unknown. The researchers found that these bacteria were able to flourish, and produce large amounts of TMAO, only in an environment of a carnitine-rich diet. For instance, after taking carnitine supplements, or eating a steak rich in carnitine, vegetarians produced far less TMAO than omnivores.