Saturated fat and cholesterol have long been the culprits in heart disease risk, but they may not be isolated criminals, according to a new study by the Cleveland Clinic.
Red meat is abundant in a compound called carnitine, which researchers found boosts levels of the chemical trimethylamine N-oxide (TMAO). Not good because TMAO promotes hardening of the arteries, a.k.a. atherosclerosis. Interestingly, carnitine didn't have the same affect on everyone in the study: Those who ate meat normally (omnivorous) produced much more TMAO than vegans or vegetarians after eating red meat.
While this doesn't change the already-established association between red meat and heart disease risk, it does reveal a new step in the process as to why there is a link and expand our understanding of how regular meat consumption affects cardiovascular health, researchers say.
And carnitine is not just found in red meat. It is also found in energy drinks and bodybuilding supplements, and even dairy. But Stanley L. Hazen, M.D., Ph.D., chair of the department of cellular and molecular medicine at the Cleveland Clinic and lead researcher of the study, says we shouldn't jump ship from meat and dairy altogether because of the new findings. "There are many dietary risk factors for heart disease. This is just a new explanation for an existing known risk factor. The amount of carnitine in dairy tends to be far less than red meat, and low-fat dairy products are excellent sources of protein and food choices, unless you're lactose intolerant."
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However, energy drinks and carnitine supplements are a different story. "We should always be wary of energy drinks and supplements of any kind. It's really buyer beware when it comes to them," says Elisa Zied, R.D.N., author of Nutrition At Your Fingertips. Dr. Hazen agrees that these supplements and their effects should be studied more, and you should ask yourself if you really even need them before choosing them over, say, a tall glass of water or a piece of fruit.
Don't think that saturated fat and cholesterol are no longer the culprits. "Saturated fat in particular is still a risk factor for both heart disease and diabetes, so less Alfredo and more pesto!" says Leslie Bonci, M.P.H., R.D., director of sports nutrition at the UPMC Center for Sports Medicine.
It's also important to remember that while the study is helpful, it's not a black-and-white issue. "The big thing that people need to take away is that people need to follow these studies. You need to be able to say, ‘Hey this is working for me. I'm better and able to take the weight off and I feel good.’ That's more important than trying to spearhead a certain nutrient," says Valerie Berkowtiz, director of nutrition at the Center for Balanced Health.
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Ronald Krauss, M.D., co-author of the study, and senior scientist and director of atherosclerosis research at Children's Hospital Oakland Research Institute, agrees that this doesn't change our current nutrition recommendations for a healthy lifestyle. He says further research is needed on how carnitine reacts in the intestines. Dr. Hazen also says the data begs for more research on energy drinks and bodybuilding supplements to see how they affect heart health.
Need a fresh reminder on what exactly you can do to keep your heart health in check? "The best first defense against high cholesterol and to optimize heart health is to follow current dietary guidelines and reduce saturated fat and cholesterol intake, have as little trans fat as possible, limit sodium, and get a wide variety of nutrients," Zied says.