This article originally appeared on Live in the Now.
Before you swear off red meat forever, there are a few things you should consider about the recent study indicating that the L-carnitine in red meat increases the risk of heart disease.
The study, performed at Ohio’s prestigious Cleveland Clinic and published in Nature Medicine, contends that the amino acid L-carnitine, found in abundance in foods like duck and beef, offers metabolic energy to a specific type of digestive microbe. Upon consuming L-carnitine, these microbes release a gas known as trimethylamine (TMA) which is later converted into trimethylamine-N-oxide (TMAO). It is theorized that TMAO interferes with the excretion of LDL cholesterol and initiates the build up of plaque on the arterial wall.
Previous studies with 23 vegetarians and vegans and 51 meat eaters indicated that meat eaters normally had more TMAO in their blood than did vegetarians, according to the New York Times.
Fueled by the hypothesis that an increase in plasma TMAO from metabolized L-carnitine is linked to atherosclerosis risk, researchers performed a combination of human and animal studies.
Healthy study participants consumed either steak or L-carnitine supplements then had their blood drawn and tested for TMAO. According to the research results, “Omnivorous human subjects produced more TMAO than did vegans or vegetarians following ingestion of L-carnitine through a microbiota-dependent mechanism,” confirming that meat eaters had a higher concentration of the types of microbes that metabolize L-carnitine.
As they continued the study on mice, researchers observed cases of heart disease accelerated in a TMAO-dependent fashion.
To test their hypothesis further, the researchers suppressed the beneficial bacteria in the guts of the meat eaters using a round of antibiotic treatments and conducted the same test. They found that after a round of antibiotic treatment, blood levels of TMAO did not rise at all.
To solidify their claims, researchers also analyzed blood from more than 2,500 individuals to determine if TMAO levels predicted cardiovascular disease (CVD) independently of traditional risk factors such as smoking, high cholesterol and blood pressure. After analysis, they concluded it did — elevated TMAO was directly linked to an increased risk of CVD.
Does This Mean You Should Give Up Red Meat?
No! While TMAO does in fact decrease the body’s ability to get rid of LDL cholesterol, thus increasing the chances that plaque will build up on the arterial wall, there are several other factors to consider before you blame the burger.
#1: The bacteria don’t come from meat.
The bacteria in question — the bacteria that metabolizes L-carnitine and produces TMAO — do not come from eating red meat. The reason meat eaters have a higher concentration of these specific types of bacteria is simply because they are feeding the bacteria the nutrients they need to flourish. In many respects, your gut is like an ecosystem. There are about 100 trillion microorganisms in the intestines made up of somewhere between 300 and 1,000 different species. And just like in any other ecosystem, if you deprive an organism of its primary food source, it will eventually die off. These bacteria are present in all humans, meat eaters simply produce more of them because they feed them.
#2: L-carnitine is still good for you and your heart.
Very good, in fact. A large and recent meta-analysis published in the journal Mayo Clinic Proceedings suggests that L-carnitine is helpful for heart disease, not a cause. High levels of carnitine only shifted the balance of microbes which increased TMAO production by tenfold. In the absence of these microbes, however, TMAO did not increase at all, as we saw in the vegan/vegetarian population.
#3: Moderation is the key.
Lead author of the study, Dr. Stanley Hazens, noted, “I’m not telling people to cut out red meat… but cut down the frequency and portion sizes.” And that’s ultimately what it comes down to: frequency and portion sizes. The kidneys filter TMAO. So while TMAO levels may spike in some individuals after eating a meal high in L-carnitine, they will go back down in time. On the other hand, if one eats red meat on a daily basis, the L-carnitine-consuming bacteria in your gut will be strong and prevalent, creating a vicious cycle.
#4: Opt for organic, grass-fed beef.
According to the Alliance for Natural Health, industrialized factory farm meat is very different from organic, local, grass-fed meat in its nutrient composition. They note, “grass-fed beef has nearly seven times more omega-3 fatty acids than omega-6 fatty acids, so eaten in moderation, it offers healthier levels of essential fats. Moreover, grass-fed beef is lower in total fat, and higher in vitamin E complex, beta-carotene, thiamin, riboflavin, calcium, magnesium, potassium, and CLA — and these differences may have a tremendous impact on both the types of bacteria in the gut and the levels of TMAO produced.”
We now know that while TMAO levels are elevated, LDL cholesterol is likely being deposited onto your arterial walls in a manner your body can’t otherwise prevent. The key, therefore, is to minimize the time your TMAO levels are elevated. Simply put, eat red meat infrequently enough that your gut flora has a nice balance of bacteria and never develops an unnatural concentration of L-carnitine consuming bacteria.
This study brilliantly underscores the fact that optimal health is never attributed to one food, factor or compound. Try to limit red meat and L-carnitine consumption to 1-2 times a week and eat heart-healthy, cholesterol-lowering foods with each meal.