Is Carnitine in Red Meat Dangerous?
Nutrition Diva explains what the latest research on red meat and heart disease means for your health and diet choices.
I heard from several of you this week, asking me to weigh in on the recent findings on red meat, carnitine, and heart disease. I’m sure you’ve seen the headlines—and maybe you heard a 90-second summary on the evening news. Even my Dad, who is not in the habit of emailing me about nutrition news, forwarded me a link to the story! But before we simply conclude that red meat causes heart disease, let’s take a closer look at what the researchers found and the implications for your daily food choices and long-term health.
What is Carnitine?
First off, what exactly is carnitine and what is it doing in our meat? Carnitine is a naturally-occurring compound that’s found in a wide variety of foods. Beef is, by far, the most concentrated source. In fact, that’s how carnitine gets its name. “Carne” is Latin for meat. But you’ll also find carnitine in pork, chicken, fish, dairy, and even soy. In fact, tempeh (which is a fermented soy food) has about 4 times as much carnitine as chicken.
That said, meat-eaters typically consume a lot more carnitine than vegetarians or vegans. And, obviously, those who eat the most red meat have the highest intake of carnitine. So, why does this matter?
What Happens to Carnitine in Your Gut?
Your large intestine, or colon, contains millions of bacteria, representing hundreds of different strains and species. And these guys aren’t just sitting around down there. They are very busy, digesting fibers and other substances that your body can’t process, producing certain nutrients and other compounds, and acting as a barrier against harmful bacteria. ¥ou can learn more about the gut microbiome in this episode by Dr. Lee Falin (aka Everyday Einstein). The precise makeup of your gut microbiome is as individual as your fingerprint. It’s affected by what you eat, where you live, medicines you take, and even your genes.
In this latest study making news, researchers found that certain kinds of gut bacteria prefer carnitine as a food source—and that when these bacteria metabolize carnitine, they produce a by-product called TMAO. This compound has been linked to atherosclerosis, or hardening of the arteries.
So what we have here is a chain of associations. People who eat the most beef tend to have the highest intake of carnitine. Those with the highest intake of carnitine tend to have the highest levels of TMAO. High levels of TMAO are linked to increased risk of heart disease.
Do We Know What Causes Heart Disease?
The significance of this finding is that it provides a potential explanation for why those who eat more red meat have a higher risk of heart disease. But let me just put that in perspective for you.
Years ago, we were pretty sure that the cholesterol in red meat was the culprit. Later, when it became clear that cholesterol in foods doesn’t have much effect on blood cholesterol levels, we decided that it was the saturated fat in red meat that explained the link. More recent evidence suggests that this too may have been a false association. Now, we have a new villain. But maybe, for once, we should resist rushing to premature or overly-simplistic conclusions. I think it’s pretty likely that the association between diet and heart disease doesn’t boil down to one food, much less a single compound or chemical reaction.
Let’s also keep in mind that carnitine has potential benefits, as well—including some that may protect against heart disease. Carnitine is a potent antioxidant, for example, and helps prevent the oxidation of fats in the blood and cell walls. Carnitine supplements have also been shown to reduce angina pain and reduce mortality in those with heart disease.
Should You Stop Eating Meat?
There’s obviously a lot more to research, discover, and understand about the relationship between carnitine, red meat, and heart disease. Meanwhile, what are we supposed to eat for dinner tonight? What are the real world implications of this latest finding for those who eat meat?
Even before this new research came along, it’s was already pretty clear that eating red meat once or twice a day is not a great idea. Eating red meat once a week, on the other hand, appears to be fine. Although I am about 80% vegetarian myself, when I do eat meat, I almost always choose red meat over chicken—and this new finding probably won’t change that. For one thing, beef is usually higher in heart-healthy monounsaturated and omega-3 fats than poultry is. For another, humanely-raised beef and lamb seems to be easier to find (and less expensive) than humanely-raised chicken.
But regardless of whether your protein of choice is prime rib, skinless chicken breast, or tofu, let’s not forget about what’s on the rest of the plate! Is it vegetables or French fries? Is it followed by fresh fruit or apple pie a-la-mode? Do you take a walk after dinner or sit down in front of the tube?
In the words of nutritionist and food activist Dr. Marion Nestle:
"The attention paid to single nutrients, to individual foods, and to particular diseases distracts from the basic principles of diet and health," she writes. "You are better off paying attention to your overall dietary pattern than worrying about whether any one single food is better for you than another."
So, by all means, let your choices be guided by the latest science! If you’re currently on the 5-steak-a-week plan, it might be time to adjust the menu a bit. But let’s resist the temptation to single out individual foods or nutrients as the cause or cure for what ails us.
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Beef image from Shutterstock