WEDNESDAY, December 29, 2021 (HealthDay News) – Red meat lovers may increase their risk of heart disease through a chain of events taking place in the gut, a new study suggests.
Many studies over the years have connected diet severe in red and processed meat to an increased risk of heart disease and stroke. However, this type of evidence does not prove that red meat is a problem – or, if so, why.
New discoveries offer more clues as to why.
Researchers have discovered this in particular intestinal bacteria, which is more common in red meat eaters, are key in converting a nutrient called carnitine into an enemy: a chemical known as TMAO, which helps promote blood clotting and clogged arteries.
For the average person, the insights confirm what is already known about a healthy diet for the heart, said study co-author Dr. Stanley Hazen, who runs the Cleveland Clinic’s Center for Microbiome and Human Health.
“Microbiome” refers to a huge collection of bacteria and other microbes that naturally inhabit the human body, especially the gut. Research in recent years has begun to reveal how vital these gut microbes are – not only in digestion, but also in immune system defense, brain functioning and health of the cardiovascular system.
It is well established, Hazen said, that people with red meat-rich diets tend to have a higher risk of heart disease and stroke than those who eat little red meat.
But, Hazen said, research has shown that any bad effect of saturated fats is not enough to explain the excessive risks of heart disease associated with high red meat consumption. There had to be other mechanisms.
The new findings point to one thing, said Lauri Wright, head of nutrition and dietetics at the University of North Florida, Jacksonville.
There is still much to learn about the gut microbiome, said Wright, who is also a spokesman for the Academy of Nutrition and Dietetics. But in general, she said, a diet rich in foods like vegetables, fruits and fiber-rich grains helps “feed” beneficial gut microbes.
“It’s still coming back to food,” Wright said.
Hazen also said he is a “big proponent” of using a diet to change the gut microbiome, instead of adding certain bugs through probiotic supplements.
“Changing the diet changes the soil that feeds intestinal microbes,” he explained.
The latest findings are based on earlier work by Hazen and his colleagues focusing on TMAO. The chemical is formed when intestinal bacteria break down carnitine, a nutrient found specifically in red meat.
Researchers have already shown that TMAO appears to increase the risk of heart disease and stroke. I ua 2019 study, found that adding red meat to the diet of healthy people for a short time increases the level of TMAO in the blood. However, these levels decreased when red meat was replaced with white or vegetable proteins.
In the latest study, observing both humans and laboratory mice, the researchers found that a set of intestinal bacteria – within the so-called Timonensis emergency – transform carnitine into TMAO. While those who eat meat have a decent amount of these microbes, longtime vegetarians and vegans have very few.
In experiments with mice, the researchers found it to be an introduction E. timonensis increased levels of TMAO and blood propensity to form clots.
Researchers also analyzed stool samples from people who participated in the 2019 nutrition study. They found that when participants ate a lot of red meat, their stool hid more culprits E. timonensis microbes; when they switched to meat-free protein sources, those microbial levels dropped.
Blood tests to measure TMAO levels in humans are available. And Hazen said it could potentially allow healthcare professionals to give patients more personal nutrition advice: if someone’s TMAO levels were high, restricting red meat would be especially important.
But what you take in, Wright remarked, is just as important as what you limit. She said fermented foods like yogurt and kimchi, which contain certain microbes, can be a good choice. But again, she pointed out, an overall diet is key to maintaining a healthy gut.
The American Heart Association has advice on this a healthy diet for the heart.
SOURCES: Stanley Hazen, MD, PhD, Director, Center for Microbiome and Human Health, Cleveland Clinic, Ohio; Lauri Wright, Ph.D., RDN, Assistant Professor, Department of Nutrition and Dietetics, University of North Florida, Jacksonville, Florida; microbiology of nature, December 23, 2021, online