Despite all we know about the risks of certain lifestyle choices like smoking, predicting life expectancy based on those choices is an inexact science. Some folks beat the odds, and some are stricken unexpectedly early. Some people smoke and live to be 100. Some folks never exercise and die peacefully in bed in their 90s. And some vegetarians have strokes in their 60s, while people who eat Big Macs daily are still kicking in their 80s.
The Problem with Red Meat
We know that the Mediterranean diet, low in red meat and dairy products, increases life expectancy (and, according to new evidence, may lessen the risk of dementia), and that the reverse is true: a diet high in red meat appears to decrease life expectancy. For a long time, we thought that this was a result of the fat and cholesterol in red meat. While fat and cholesterol may play a role, recent research has revealed a fascinating new connection between red meat consumption and atherosclerosis, the process that leads to vascular blockage and subsequent heart attacks and strokes.
What the New Findings Mean
According to this new work, first released in the biomedical research journal Nature Medicine, the bacteria in the intestines of meat eaters convert carnitine, a chemical abundant in red meat, into trimethylamine-N-oxide (TMAO), which increases cholesterol deposition and decreases cholesterol removal from arterial cell walls. Interestingly, when vegetarians eat a large meal of red meat, their TMAO levels don’t rise. The implication is that our eating patterns influence the bacteria we carry in our digestive tracts, and that this affects the way we metabolize our food, which in turn affects our cholesterol metabolism. Scientists have discovered a similar result with lecithin, which is abundant in eggs.
Although high TMAO levels are associated with an increased risk of atherosclerosis, we don’t know whether lowering TMAO levels can reduce the incidence of cardiovascular disease. That’s the next step in pursuing this line of research to a point where clinical intervention may be possible. Notably, the study’s investigators found that when they gave regular red meat eaters an antibiotic followed by a steak, the participants’ TMAO levels did not rise. So perhaps–this is pure speculation at this point–in the future, we could alter the bacteria in our guts (with antibiotics, probiotics, or by some other means) and prevent heart disease!
What You Can Do to Reduce Your Risk
Right now, your best bet is to eat a healthy diet low in red meat, such as the Mediterranean diet, and to exercise regularly, maintain a healthy weight, manage stress, and to quit smoking. We’ll keep you posted on the future of this unexpected research into cardiovascular disease prevention.