We often say that healthy eating should eat less red meat, and a new study published recently shows that eating more red meat may increase our risk of cardiovascular disease through a series of changes that occur in the intestine.
Over the years, many studies have demonstrated the association between eating more red meat and processed meat diets and increasing the risk of cardiovascular disease and stroke, but most of them are proved by statistical analysis, but there are few specific studies on why eating too much red meat increases the risk of cardiovascular disease.
A recent discovery gives us more clues about the "why."
The results of a study led by the Cleveland Clinic's Center for Microbiome and Human Health, published in the journal Nature Microbiology, reveal the physiological mechanisms by which red meat may have an impact on cardiovascular health.
In the study, the researchers found that a specific gut bacteria in our gut microbiota was able to convert the rich L-carnitine in red meat into a substance called "trimethylamine oxide (TMAO)", which helps promote blood clotting and blockage of arteries, accelerating the atherosclerosis process, thereby increasing the risk of cardiovascular disease and stroke.
New research reveals cardiovascular risks associated with eating more red meat
I believe that many friends know that the human body naturally inhabits a large number of microorganisms, especially the intestine is rich in intestinal flora, a variety of intestinal flora not only helps the body's digestion and absorption, but also plays an important role in immune defense, brain function and cardiovascular health.
Dr. Stanley Hasson, director of the Cleveland Clinic's Center for Human Health, one of the study's co-authors, noted that people with a high diet with a higher risk of heart disease and stroke than those who eat less red meat are well known, but we usually blame it on the high levels of saturated fat in red meat, and in fact, while excessive intake of saturated fat increases the risk of elevated LDL cholesterol, this adverse effect is not enough to explain the increased risk of cardiovascular disease associated with eating large amounts of red meat. So they studied other mechanisms.
In the new study, the researchers found that the dietary carnitine in the meat we eat in the intestine, through two steps, the biotransformation of two microorganisms, can be converted to trimethylamine oxide, after carnitine enters the intestine, a variety of microorganisms in the intestinal flora will convert it into an intermediate metabolite γ-butyl betaine, while the Emergencia timmonensis in the intestinal flora will further convert γ-butyl betaine into trimethylamine oxide.
Studies have shown that in omnivorous animals, this microorganism is the main gut microbe that converts carnitine to oxidized trimethylamine, while in long-term vegetarians or vegans, the amount of this microorganism in the intestine is very low, not enough to convert carnitine into trimethylamine oxide. That is to say, if you love to eat meat more, the red meat you eat into more intestinal bacteria will be converted into trimethylamine oxide, in a sense, the meat we eat promotes the multiplication and growth of this intestinal bacteria.
These findings are actually based on earlier research work, in a 2019 study, scientists found that adding red meat to the diet of healthy people for a short period of time raises the level of trimethylamine oxide in the blood, and when red meat is replaced by white meat or plant protein, the level of trimethylamine oxide falls back.
In the new study, researchers studying human and laboratory mice found that the gut bacterium Emeraldcia timonensis is the main strain that converts carnitine into trimethylamine oxide, while meat eaters use a considerable amount of this microorganism, but the amounts in long-term vegetarians are low.
Mouse studies have found that increased levels of trimethylamine oxide are at risk of causing blood clotting to form blood clots.
Implications of the study
Dr. Hasson noted that for the average person, these insights reinforce people's understanding of heart-healthy eating.
He also specifically pointed to the traditional Mediterranean diet, which clinical trials have shown can reduce the risk of heart disease and stroke. This diet is rich in fish, fruits and vegetables, legumes, olive oil and nuts, while red meat and processed foods are lower.
For the study, the researchers also analyzed stool samples from participants in the 2019 diet study. The study found that when participants ate large amounts of red meat, their feces contained more culprit E. Timonensis microbes; and when they switched to foods from non-meat protein sources, these microbial levels also declined.
This shows that our diet will have an impact on the intestinal flora, and changing the diet helps to regulate the intestinal flora and improve the health of the human body, and changing the diet, especially the diet that is rich in foods such as vegetables, fruits or other high dietary fiber cereals, can help provide a better environment for the beneficial microorganisms in the intestine and promote the multiplication and growth of these "probiotics".
Since the content of trimethylamine oxide in the blood can be evaluated and measured, and the content of this harmful substance is closely related to the increased risk of cardiovascular and cerebrovascular diseases, the study also provides us with a scientific dietary indication, if the measurement of people with high levels of trimethylamine oxide in the blood, we should pay more attention to eating less red meat.
Therefore, on the question of how to eat meat, pigs, beef and mutton and other red meat is not impossible to eat, but if it is a special friend who loves to eat these meats, you may wish to try to reduce the proportion of vegetables in the diet, and try to increase the intake of vegetables, fruits, whole grains, in the choice of meat, you can choose poultry, fish and other white meat, eat 2 to 3 times a week, the daily diet can also provide high-quality protein for the body through beans, soy products, milk, eggs, etc., so that they can eat healthier, our intestinal flora will be healthier, A healthier intestinal flora and intestinal environment will not only protect our ability to absorb nutrients, but also help to enhance immunity and protect cardiovascular health, which is worth our long-term adherence.