That zippy power potion might keep you buzzing clear through the afternoon. But it might clog your arteries. Carnitine, a compound popular in energy drinks has been found to promote atherosclerosis.
Carnitine's naturally abundant in red meat and an added ingredient to many energy drinks. Research from the Cleveland Clinic, published online in the journal Nature Medicine, shows that bacteria living in our digestive tracts metabolize the stuff into TMAO, or trimethylamine-N-oxide. This is not an acronym you want hanging out in your body. In 2011, researchers linked TMAO to the promotion of athereosclerosis in humans, according to the Cleveland Clinic release. In addition, the new research found that a diet high in carnitine promotes the growth of the bacteria that metabolize carnitine, compounding the problem by producing even more of the artery-clogging TMAO. If you're an energy drink guzzler or a steak eater, and especially if you're both, it seems like it's TMI (Too Much Information) about carnitine and clogged arteries. And none of it will make you LHO (Laugh your Head Off).
The study tested the carnitine and TMAO levels of omnivores, vegans and vegetarians, and examined the clinical data of 2,595 patients undergoing elective cardiac evaluations. They also looked at the cardiac effects of a carnitine-enhanced diet in normal mice compared to mice with suppressed levels of gut microbes. They found that TMAO alters cholesterol metabolism at multiple levels, explaining how it enhances atherosclerosis.
The researchers found that increased carnitine levels in patients predicted increased risks for cardiovascular disease and major cardiac events like heart attack, stroke and death, but only in subjects with concurrently high TMAO levels. Additionally, they found specific gut microbe types in subjects associated with both plasma TMAO levels and dietary patterns, and that baseline TMAO levels were significantly lower among vegans and vegetarians than omnivores. Remarkably, vegans and vegetarians, even after consuming a large amount of carnitine, did not produce significant levels of the microbe product TMAO, whereas omnivores consuming the same amount of carnitine did.
In an update to this amino acid drama, a week later a study published in Mayo Clinic Proceedings reported that L-carnitine significantly improved cardiac health in patients after a heart attack.
Prior research has shown that a diet with frequent red meat consumption is associated with increased cardiovascular disease risk, but that the cholesterol and saturated fat content in red meat does not appear to be enough to explain the increased cardiovascular risks. What made the difference? Scientists suggested genes, a high salt diet often associated with red meat consumption and maybe even the cooking process. This new research finally helps explain the discrepancy, and the actual connection between red meat and cardiovascular disease. "Carnitine metabolism suggests a new way to help explain why a diet rich in red meat promotes atherosclerosis," says lead researcher Stanley Hazen, M.D., Ph.D., Vice Chair of Translational Research for the Lerner Research Institute and section head of Preventive Cardiology & Rehabilitation in the Miller Family Heart and Vascular Institute at Cleveland Clinic in a release.
He warns that more research needs to be done to examine the safety of chronic carnitine supplementation."Carnitine is not an essential nutrient; our body naturally produces all we need," says Hazen. "We need to examine the safety of chronically consuming carnitine supplements as we've shown that, under some conditions, it can foster the growth of bacteria that produce TMAO and potentially clog arteries." For energy drink manufacturers, this research LLT (Looks Like Trouble).